Got something to throw out there.. I’ll try to include as many details as I can
Myself (plumber) and a couple of our hvac guys installed 2 new RBI dominator boilers for a high school pool. 2 1/2” copper lines in and out... The boilers and circ pumps and mixing valve were purchased from a local boiler supply house who sells the entire package together as a unit so I have to assume things are all specd to work together. We have purchased and installed roughy half a dozen of this set up with no issues.. Pump is B&G with 3” flanges and volute. I don’t know why it’s 3” when boiler inlet and outlet is 2 1/2 but..? Male adapters and Reducers on either side of the flanges.
1st time plumbed it all in using Apollo crimp fittings. All good. Approx 2 months and pinhole leak from just below the pump. (Pump pulls water and feeds into boiler inlet) Said what the hell...? Maybe a bad piece of copper. Cut it out and noted it was quite pitted but only in certain areas.. Replaced the section but sweat this time just to remove the crimp fittings from the equation.
Maybe 2 months and pinhole in the exact same spot. Cut it out and the same thing.... I’ve seen plenty of copper eaten away from much too powerful circ pumps. And that on domestic lines. This is obviously chlorinated pool water but we have 4 other pools and nothing like this. Again this is one of 2 identical boilers side by side and the other has experienced no problems
Toss some ideas out.. I’m sure I missed a few things but I’ll try to answer any questions
Cavitation.....its a biotch. Can your 90 be any farther away?
That’s my general suspicion and have seen it elsewhere but never this extreme...?? What’s odd is this boiler has an exact twin right next to it with no problems..? Same pool(water chemical concentration) same pump same boiler and plumbed identically
Looks like iron in the water, copper and who knows if a water treatment chemical. Have been causing electrolysis, in a cavitation eddy! This happens behind pipe joints and elbows most often! Extra grounding may be in order!
Cavitation.....its a biotch. Can your 90 be any farther away?
That’s my general suspicion and have seen it elsewhere but never this extreme...?? What’s odd is this boiler has an exact twin right next to it with no problems..? Same pool(water chemical concentration) same pump same boiler and plumbed identically
Could be a difference in casting or the upstream flow characteristics....possibly inaccuracies in the frequency drive....just possibilities.
Not ruling anything out.. care to elaborate? I understand dissimilar metal corrosion and that chlorinated pool water does not help that equation, but this seems awfully extreme and isolated?
Are you operating on a performace spec or prescriptive spec?
e.g. - are you building off a set of design plans that say install this . . . or are you just told install something that works?
MM..more so the latter. To be honest it’s new territory and a few of us just do the installs to learn. The company we buy the system from comes out and does the initial start up in accordance with warranty.. and they always pass, and in fact compliment the install..
There was probably a reason for pump coming with three inch flange on suction side. May need to run three inch line to boiler and reduce at boiler to 2 1/2” to stop cavitation. Most every fluid pump needs a larger suction than discharge line. May also be wise to use dielectric union at pump in case of electrolysis.
It does resemble a stress fracture along a seam, perhaps with chemical compromising (accelerated damage) (pitting) caused by the product being pumped. If it were cavitation alone, I don't think there would be chemical residue.
Is the setting properly supported? Does this section need a flexible joint? Is the pump overated for the job at hand? If the pump is overated, then a recirc line would be needed to accomodate the flow requirements at low load. Just my initial thoughts.
There is also that threaded fitting downstream which might have incurred alot of twisting torque during assembly, which if so, could have stressed the tubing.
Not ruling anything out.. care to elaborate? I understand dissimilar metal corrosion and that chlorinated pool water does not help that equation, but this seems awfully extreme and isolated?
I had a great article on this topic at one time that wasn't ever saved digitally so it's history.
There was a top notch boiler company that had installed a a unit in a older apartment building. They rotted the tubes out of the boiler inside of two years, twice.
They became aware they were facing a electrolysis issue but couldn't pin down the source.
Dielectric fittings (which I don't see in your images?) were not preventing their problem.
To make a long story short, they found that over many years of DIY'er type of electrical maintenance throughout the building the neutral lead had been bonded to the ground lead in many locations including sub panels and even some electrical outlets.
Bonding of ground and neutral leads can only be done at 'first strike'. Which typically means at the main service feeding a structure and never again after that point or electrolysis is likely to occur.
Grounding rules and regulation make up the bulk of the NEC code book and the specifics bewilders MOST electricians. I've quizzed many life long electrical Journeymen and Administrators on the specifics of proper grounding of industrial equipment and steel buildings and sent them all to their NEC code book digging for answers.
Most electrical systems have grounds bonded to the water mains feeding a structure, right at those pumps is a likely location for electrolysis to occur.
It's interesting that it 'appears' your issue is limited to the one unit. If that's truly the case you may find your problem local on that boiler, but that's rather wishful thinking.
What I would do immediately would be to ground the living schit out of the boilers chassis. I'd run some heavy copper (4/0) to a dedicated ground rod, or two. Find a good location on the boiler to bond to and grind the pretty paint off that brand new boiler and get a solid bonding point. De-ox the connections well.
It sucks that this isn't nessarally a plumber's problem but could very well be the plumber's problem to prove.
If grounding the unit corrects the issue I'd recommend, in writing, for the school to have a electrical contractor do some forensics work and locate the source of the problem or atleast have both boilers grounded with a cad weld grounding system so it can never be removed. It is a kids swimming pool with a potential unknown electrical problem.
But that's just my two cents worth, what'da I know, I'm not even a electrician...
Did you put a meter on it to see if there's any stray current?
Typically if we could stay 10ish pipe diameters before the fittings it smoothed out....5 was the minimum but often not enough to stop cav.
HC, have not done that, will check tommorow
That could be very difficult to get a proper reading. If it's the ground that is carrying voltage what would you connect the negative lead of your meter to?
It does resemble a stress fracture along a seam, perhaps with chemical compromising (accelerated damage) (pitting) caused by the product being pumped. If it were cavitation alone, I don't think there would be chemical residue.
Is the setting properly supported? Does this section need a flexible joint? Is the pump overated for the job at hand? If the pump is overated, then a recirc line would be needed to accomodate the flow requirements at low load. Just my initial thoughts.
Nice photo display!
Thanks SC... some thoughts in reply If it were steel pipe I’d assume a weak seam of sorts as well but we’re dealing with copper here. What are you referring to specifically by chemical reside? If you mean the green tint yes these lines are pumping chlorinated water and I know that’s not helping the situation.. The assembly is supported with hanging bracket up top and strut bracing below. The whole assembly was soldered up and slipped into place with no stress incurred.
I can only assume the pump is properly sized for the job as it is sold to us a package by the boiler company who installs and warranties the same setups... However I will call and ask why the supplies pump/flanges are 3” when boiler is 2 1/2 as that makes no sense to me.
JeffA.. some good ideas there thank you You nailed it that it seems to be a problem in my lap!
I will look into how/if this boiler is grounded. I “think” there is a grounding strap coming off the backside but how what where it goes I can’t recall
You are also correct in that it only “appears” this is isolated. Without cutting the other boiler lines open I can’t be sure. The only thing I can be sure of is these lines have failed twice and the other has not.
I suspect there is at least a contributing issue with the volute/impeller being imperfect and causing cavitation and flow issues... I was told the pump seal had failed a while back (less than a year old) and the impeller was in bad shape and replaced as well at that time. I heard the impeller housing was not in great shape and getting the new impeller in was “tricky”. Obviously that’s not good..
Did you put a meter on it to see if there's any stray current?
Typically if we could stay 10ish pipe diameters before the fittings it smoothed out....5 was the minimum but often not enough to stop cav.
HC, have not done that, will check tommorow
That could be very difficult to get a proper reading. If it's the ground that is carrying voltage what would you connect the negative lead of your meter to?
I'd pull impedance from the area in question to a known ground. I'd check ac voltage from the same.
Then I would go across the piping on both sides of the pump with impedance.
My facility is littered with rotten copper. I've chased down most of the ac bleeds and cavitation.
HC..I’m on board with what you’re saying, but I just don’t know how to do it.. Can you walk me thru (plumber) specifically how I would check These things with my meter
“go across the piping on both sides of the pump with impedance” .....mostly this part Thanks
I've been a plumber for quite a while, but have limited experience with boilers. Mostly I just pipe them up according to the design, so keep that in mind when I say this; I thought it was commonly accepted that "pumping away" (there's an article on this by the same name) from a boiler was the preferred way, as it kept turbulence inside the boiler and the various devices, (low water limit, etc) located near the boiler, to a minimum.
Suction side of pump or discharge ? Chlorine and Copper usually not a good combo in most Water treatment feed lines I have been around most were Schedule 80 PVC with glues that rated for chlorine. Looks like cavitaion to me the 90 is not helping. Just a guess. If its disharge on the pump any air bleeds installed?
I've been a plumber for quite a while, but have limited experience with boilers. Mostly I just pipe them up according to the design, so keep that in mind when I say this; I thought it was commonly accepted that "pumping away" (there's an article on this by the same name) from a boiler was the preferred way, as it kept turbulence inside the boiler and the various devices, (low water limit, etc) located near the boiler, to a minimum.
You and I seem to be in the same boat, and yes your pumping away logic makes sense to me
Suction side of pump or discharge ? Chlorine and Copper usually not a good combo in most Water treatment feed lines I have been around most were Schedule 80 PVC with glues that rated for chlorine. Looks like cavitaion to me the 90 is not helping. Just a guess. If its disharge on the pump any air bleeds installed?
Discharge side of pump. And yes the 90 is close but again the location and specific nature of the pitting is what’s curious. I have seen the harsh effect of oversized circ pumps on copper systems many times at my sites and this just doesn’t match up
Was the 90 ell replaced both times or not all all? You reaming all cuts?
Any chance a gob of solder or a burr from the cut was left behind?
That's erosion from some source that close to the ell.
If it was electrolysis or chemical, It would be appearing in other areas also.
Kenneth all fittings and pipe were replaced. Reamed proper and no chance of a burr as I’m anal x10 about fitting/pipe prep... I’m sure you understand that I’ll check for a gob of solder but man I’m pretty careful about that as well.. I agree that the easy answer is electrolysis or chemical but it just doesn’t add up to me... Some harsh and very localized turbulence seems most likely to me but I’m reaching for the why and how
As others have said, electrolysis is what I would say your problem is. I would be looking to see if there is stray current on the piping by putting a volt meter on it to ground and see what you got. I would also put dielectric gasket kits on the pump flanges if the pump is cast iron.
HC..I’m on board with what you’re saying, but I just don’t know how to do it.. Can you walk me thru (plumber) specifically how I would check These things with my meter “go across the piping on both sides of the pump with impedance” .....mostly this part Thanks
Checking for continuity across the pump piping and check for voltage while you're at it.
I suspect there is at least a contributing issue with the volute/impeller being imperfect and causing cavitation and flow issues... I was told the pump seal had failed a while back (less than a year old) and the impeller was in bad shape and replaced as well at that time. I heard the impeller housing was not in great shape and getting the new impeller in was “tricky”. Obviously that’s not good..
If both units are cloned, swap the pumps and see if your issue transfers to the other boiler.
Some years ago I was involved in the construction of two community swimming pools. When the swimming park opened one of the pools was slowly corroding the pool ladders, fixtures, and plumbing and swimmers would report a tingling sensation when entering and exiting the pool. Inspectors closed the pool and spent tons of money trying to pinpoint the problem.
Turns out it was a defective underwater pool light electrifying the entire system.
Not saying this is the cause of your issue but something to consider.
Some years ago I was involved in the construction of two community swimming pools. When the swimming park opened one of the pools was slowly corroding the pool ladders, fixtures, and plumbing and swimmers would report a tingling sensation when entering and exiting the pool. Inspectors closed the pool and spent tons of money trying to pinpoint the problem.
Turns out it was a defective underwater pool light electrifying the entire system.
Not saying this is the cause of your issue but something to consider.
Morewood thanks for that and yes it’s definitely something to consider. Interesting possibility but I’m not sure how I could even begin to check that within the parameters we operate in around here
If so, the 3 way valve up line is in a perfect position to starve or cause the pump to cavitate. I'd take a hard look at it. Proper installation, &/or faulty?
If this is mechanical damage, it could be caused by incorrect impeller to casing clearance. You did mention that the pump went together with difficulty.
Been heating with boilers all my life. Had to change the volute on my B&G this winter, surprised to see made in China,
Couple thoughts
* bad piece of copper * stray voltage * pool water reacting with metals. May have to put in a water exchanger , like salt water boats . * kids pissing in pool.
If so, the 3 way valve up line is in a perfect position to starve or cause the pump to cavitate. I'd take a hard look at it. Proper installation, &/or faulty?
This is the bronze impeller on the problem boiler today.. the other impeller is stainless.
Cisco!! I’d rather discuss fine .22’s with you than this crap... Bronze impeller above was $600 alone and made in China
The external heat exchanger is a great solution to keep pool water away from sensitive metals but is ungodly expensive and we’d rather do it on the cheap than the right way... you know how that goes...
I don’t see any signs of cavitation, but it is only one picture. Does it look like mechanical/foreign object damage or cavitation till pieces came off?
I don’t see any signs of cavitation, but it is only one picture. Does it look like mechanical/foreign object damage or cavitation till pieces came off?
To me it appears cavitation till the pieces gave way
I don’t see any signs of cavitation, but it is only one picture. Does it look like mechanical/foreign object damage or cavitation till pieces came off?
To me it appears cavitation till the pieces gave way
Two bad impellers. Foreign matter in the system or pump starvation seems to be the only thing shy of 2 being faulty from the start. So the pump does seem to have been starved.
FPE says the valve can be used in any orientation so disregard my comment on proper installation. But it's still a possible obstruction of flow to the pump. A suspect.
I don't suppose an operator is getting their inline manual valve opening/closing sequence wrong.
CVPC will isolate elctorolysis from the poolside, suspect air causing cavitation, recheck air relief, and any suction side air leaks. Most pump issues are on suction side. Think simple and simple again.
Electrolysis will occur over time. That is cavitation to be doing that much damage that quick. You need a straight suction line to suction side of pump to prevent turbulence and possibly a larger suction line. Not saying you don't have a electrolysis problem also, but it wouldn't cause that much damage that quick.
Chuck I agree..damage from cavitation was my thought from the get go. I have repaired many issues caused by electrolysis but this damage is much too specific and quick to fit that bill on its own.
Also don’t disagree with you and many of the other posters that there may still be some dissimilar metal corrosion at play..
I’ll grab a pic but the wax mixing valve is 2 1/2” and while it’s possible to go back far enough to grab 4” copper, I’m not sure that’s going to accomplish anything in regards to a larger suction line
Chuck I agree..damage from cavitation was my thought from the get go. I have repaired many issues caused by electrolysis but this damage is much too specific and quick to fit that bill on its own.
Also don’t disagree with you and many of the other posters that there may still be some dissimilar metal corrosion at play..
I’ll grab a pic but the wax mixing valve is 2 1/2” and while it’s possible to go back far enough to grab 4” copper, I’m not sure that’s going to accomplish anything in regards to a larger suction line
Are both pumps piped in the same? Does the one causing the problems have a 90 or other fitting closer to vanes and volute? If electrolysis was doing that, people would be getting "shocked'" from touching floating grounds with that much circulating currents. Let's face it, almost every electric pump circulating system will have "stray" currents circulating to lesser impedance to earth grounds. You have a turbulence or suction staving problem.
The blue wax mixing valve is front and center. As it sits it receives hot water (165) from boiler on the left and mixes it with incoming (80) pool water on the right to send tempered water down to the pump and into the boiler.
It’s purpose is to reduce condensation in the boiler combustion chamber..
Point is it’s all 2 1/2 and is the mixing valve is supplied by the seller of these “systems”...
If you follow the pipe going away from the right side you can see back where it reduces down from 4 to 2 1/2, so in regards to increasing suction side.. it technically could be done. But I’m not convinced that would accomplish anything? post images
The blue wax mixing valve is front and center. As it sits it receives hot water (165) from boiler on the left and mixes it with incoming (80) pool water on the right to send tempered water down to the pump and into the boiler.
It’s purpose is to reduce condensation in the boiler combustion chamber..
Point is it’s all 2 1/2 and is the mixing valve is supplied by the seller of these “systems”...
If you follow the pipe going away from the right side you can see back where it reduces down from 4 to 2 1/2, so in regards to increasing suction side.. it technically could be done. But I’m not convinced that would accomplish anything? post images
Swap mixing valves between systems. Perhaps the one has a spool piece not operating properly and is starving suction between ports. Just be out some time and maybe six gaskets at worst. Don't take this the wrong way, but the one isn't put in backwards is it, closing one port when it should be opening it. I've done things like that myself, looks like it would be easy to do.
I’m gonna have to go look at some we have. We don’t have three way valves like yours or pumps. The pool pump makes water flow through the heater. Butterfly valve in the 6” line is partially closed between two 6 x 2 1/2 tees. That forces water through the pool heater as I recall. The water isn’t real hot coming out of the heater, guess that’s why it’s all cpvc. I cant remember which brands we use. I’m off all week but I’m gonna check Monday. I’m curious now. I’ll take some pics of the set up we have.
No offense taken at all chuck I said I’m open to ideas and I meant it.. Swapping the valves is an option..but they are for sure plumbed in correctly.
And if one side was closed off the boiler would for certain go out on low flow or high limit. They are quite sensitive in that regard
Yeah, I figured it was piped in right. Just a thought. It's not your job to solve the electrolysis problem if there is one, only to stop it from damaging your pump. An easy way to do this is to attach ground clamps around piping in and out of pump and install a ground wire parrallel to pump. Contrary to what some people think, parrallel circuit of different impedance won't share loads. Less impedance path will carry all currents which will be your ground wire around pump. If just as a experiment, looking at your soldering job, you wouldn't have any problem soldering a #10 solid copper wire to each side of pump piping for a jumper. Is there a way to throttle discharge slightly to reduce gpm flow thru pump? This might reduce cavitation or help diagnose problem. Pump may be of size to be able to move more water than suction line will provide. I have had to trim centrifugal pump rotors in a lathe before for this reason. Are the nameplates of both pumps the same GPM rating? You mentioned they had different impellors. the bad one isn't a higher rated GPM is it?
That assembled discharge looks like it could easily have a path to ground, electrolytic action, copper to steel rub points from wear, and of course compromised piping.
I would alter the pump support to become a hung suspension instead of the mess created by the saddle support. It should be a no brainer to replace the discharge piping long before it is looking like that.
It could be possible that you have copper supporting too much weight, both in compression and tension. You could probably provide support at the heavy device flange bolts instead.
That assembled discharge looks like it could easily have a path to ground, electrolytic action, copper to steel rub points from wear, and of course compromised piping.
I would alter the pump support to become a hung suspension instead of the mess created by the saddle support. It should be a no brainer to replace the discharge piping long before it is looking like that.
Fair enough observations but a few points. The entire assembly is supported from above not just the strut assembly you see below. It is heavily wrapped between the strut and clamp and there is no contact. It is quite corroded but only due to the lower pump gasket leaking for several weeks before it was noticed. There is no corrosion like that anywhere else
It could be possible that you have copper supporting too much weight, both in compression and tension. You could probably provide support at the heavy device flange bolts instead.
No offense taken at all chuck I said I’m open to ideas and I meant it.. Swapping the valves is an option..but they are for sure plumbed in correctly.
And if one side was closed off the boiler would for certain go out on low flow or high limit. They are quite sensitive in that regard
Yeah, I figured it was piped in right. Just a thought. It's not your job to solve the electrolysis problem if there is one, only to stop it from damaging your pump. An easy way to do this is to attach ground clamps around piping in and out of pump and install a ground wire parrallel to pump. Contrary to what some people think, parrallel circuit of different impedance won't share loads. Less impedance path will carry all currents which will be your ground wire around pump. If just as a experiment, looking at your soldering job, you wouldn't have any problem soldering a #10 solid copper wire to each side of pump piping for a jumper. Is there a way to throttle discharge slightly to reduce gpm flow thru pump? This might reduce cavitation or help diagnose problem. Pump may be of size to be able to move more water than suction line will provide. I have had to trim centrifugal pump rotors in a lathe before for this reason. Are the nameplates of both pumps the same GPM rating? You mentioned they had different impellors. the bad one isn't a higher rated GPM is it?
Chuck.. attaching a jumper is an interesting idea and I will look into that. I don’t think there is any way to throttle down the discharge.
Both motors and pump assemblies are identical with the only difference being one has the stainless impeller. I’m not 100% sure how that came to be...?
At this point the only certainties I have are the bronze impeller is utterly destroyed and the stainless impeller is still going strong. And it has been pulling duty longer to boot.
I’m surprised to see how bad that bronze impeller was, and hopeful it was directly causing the cavitation issues in the pipe. Of course back to square one with what caused that impeller to fail in such a manner and so quickly
I would look at overhead support only at each flange of the mixing valve, to keep it simple and a clean install, and look into steel braided (or whatever) flexible discharge line to the boiler, if compatible with chlorine. The pump might appreciate it's own support. I would stray away from supporting too much weight with the copper piping.
CVPC will isolate elctorolysis from the poolside, suspect air causing cavitation, recheck air relief, and any suction side air leaks. Most pump issues are on suction side. Think simple and simple again.
KK..there are Hoffman bleeders atop each of the three sediment filter tanks. Checked them and all appear to be in working order
The picture shows your corrosion look at where the copper pipe is attached to pipe bracket, look at bracket corrosion, the bracket is not insulated from the copper pipe. Dissimilar metal corrosion is what is showing in that picture.
But impellor wear is caused by cavitation, at one of the water plants I worked we had a wall of shame with many impellors that looked exactly like that.
Link shows pictures of cavitation on pump impellors
I would look at overhead support only at each flange of the mixing valve, to keep it simple and a clean install, and look into steel braided (or whatever) flexible discharge line to the boiler, if compatible with chlorine. The pump might appreciate it's own support. I would stray away from supporting too much weight with the copper piping.
I get what you’re saying and while I think it’s supported pretty well.. yes the motor/pump and mixing valve are pretty heavy. It’s worth looking into..
Different layout here but same system and used strut to directly support the pump assembly
The picture shows your corrosion look at where the copper pipe is attached to pipe bracket, look at bracket corrosion, the bracket is not insulated from the copper pipe. Dissimilar metal corrosion is what is showing in that picture.
But impellor wear is caused by cavitation, at one of the water plants I worked we had a wall of shame with many impellors that looked exactly like that.
Link shows pictures of cavitation on pump impellors
KK do you mean in the near boiler with the corrosion leaving the pump? If so while I understand how it looks of you zoom in you’ll see a very thick wrap fully insulting the pipe from the clamp and strut. I wrapped it myself. That is all from a good sized leak that went unnoticed and bathed that section in chlorinated water for several weeks
The blue wax mixing valve is front and center. As it sits it receives hot water (165) from boiler on the left and mixes it with incoming (80) pool water on the right to send tempered water down to the pump and into the boiler.
It’s purpose is to reduce condensation in the boiler combustion chamber..
Point is it’s all 2 1/2 and is the mixing valve is supplied by the seller of these “systems”...
If you follow the pipe going away from the right side you can see back where it reduces down from 4 to 2 1/2, so in regards to increasing suction side.. it technically could be done. But I’m not convinced that would accomplish anything? post images
The 3 – 2.5 reducer on top of the B&G manifold receiving the water from the mixing valve is your problem.
It is causing a pressure drop as the water transitions from the 2.5 dia piping out of the mixing valve into the larger 2.5/3.0 reducer. The pressure drop is allowing the oxygen in the water to expand and create air bubbles as the pressure drops. It is essentially doing the exact same thing as what happens in a refrigeration system right at the metering device, where liquid refrigerant (Your case – liquid water) transitions from high pressure to a lower pressure and changes from a liquid state to a gaseous state (liquid > liquid w/bubbles > gaseous state).
Your pump is getting that (liquid w/ oxygen bubbles), and possibly a lot of bubbles.
The mixing valve is mounted too close to the pump for the water to settle back down to a solid column of water after coming out of the 3.0 dia. opening of the reducer, and before entering the pump intake. Think holding a water hose with a solid stream of water into a tank, and creating bubbles below the surface. The bubbles eventually dissipate into the surrounding water, and some rise to the surface. The pump is too close to the 2.5/3.0 reducer, and not giving the liquid enough time to settle back down.
You might need 5-10 ft of 3.0dia. transition piping entering that pump, to allow for blending back into a solid state of water after coming out of the 2.5/3.0 reducer, which would be mounted back around the mixing valve. Looking at the layout, I highly doubt you have enough room presently between the mixing valve and manifold to accomplish what you need to. That means mounting the mixing valve further back overhead between the two supply feeds (back over above the first boiler with the SS impellor), and putting the 2.5/3.0 reducer further back and running 3.0 dia from there to the pump manifold. You’ll need to relocate both mixing valves.
Also, in the installation instructions there should be a section discussing piping lengths when transitioning from one size to another and how far away the fitting needs to be from the entrance side of the pump manifold.
If you don’t find it in the instructions (Might look on line at their site if you don’t have them on site) I would call tech support at B&G, and get one of their brains on the phone, and text them your pics, and see if they don’t agree with what I just said. I just looked on B&G site. It looks like they don’t make a 2.5 dia. pump. Looks like they go from 2.0 – 3.0, so you have to use a 2.5-3.0 reducer.
Copy and paste this analysis I just wrote and send it to the tech support guy in an email, so they can get their head wrapped around what I just said, so you don’t have to reread it to them.
I agree 100% on this being a cavitation issue, way too rapid for electrolysis to be the culprit.
Great video, I like them when they are short and to the point like that.
The following came up as recommended by YT while viewing your link. Another great simulation but without the veritable freak drive for manipulation and done with a pump and plumbing system designed for observation.
I'm curious with the stainless vs bronze impellers if material isn't the only difference. Could the pitch also be different and creating a different volume/flow/pressure while operating at the same RPMs?
I'm happy to see this one stay on target. I agree on the reduction....I'd try to feed and discharge at 100% pipe diameter without any fittings for at least 15" for best hope.
The pumps are going to cavitate....how much and how it affects the downstream piping will be dependent on how fast the pumps are ate up and how the actual flow ends up settling in.
Buying yourself 5-10 pipe diameters of straight run piping is your first line of defense. There may be opportunity to reduce the cavitation by changing pump rpm, introducing flow or suction stabilizers....etc.
The blue wax mixing valve is front and center. As it sits it receives hot water (165) from boiler on the left and mixes it with incoming (80) pool water on the right to send tempered water down to the pump and into the boiler.
It’s purpose is to reduce condensation in the boiler combustion chamber..
Point is it’s all 2 1/2 and is the mixing valve is supplied by the seller of these “systems”...
If you follow the pipe going away from the right side you can see back where it reduces down from 4 to 2 1/2, so in regards to increasing suction side.. it technically could be done. But I’m not convinced that would accomplish anything? post images
The 3 – 2.5 reducer on top of the B&G manifold receiving the water from the mixing valve is your problem.
It is causing a pressure drop as the water transitions from the 2.5 dia piping out of the mixing valve into the larger 2.5/3.0 reducer. The pressure drop is allowing the oxygen in the water to expand and create air bubbles as the pressure drops. It is essentially doing the exact same thing as what happens in a refrigeration system right at the metering device, where liquid refrigerant (Your case – liquid water) transitions from high pressure to a lower pressure and changes from a liquid state to a gaseous state (liquid > liquid w/bubbles > gaseous state).
Your pump is getting that (liquid w/ oxygen bubbles), and possibly a lot of bubbles.
The mixing valve is mounted too close to the pump for the water to settle back down to a solid column of water after coming out of the 3.0 dia. opening of the reducer, and before entering the pump intake. Think holding a water hose with a solid stream of water into a tank, and creating bubbles below the surface. The bubbles eventually dissipate into the surrounding water, and some rise to the surface. The pump is too close to the 2.5/3.0 reducer, and not giving the liquid enough time to settle back down.
You might need 5-10 ft of 3.0dia. transition piping entering that pump, to allow for blending back into a solid state of water after coming out of the 2.5/3.0 reducer, which would be mounted back around the mixing valve. Looking at the layout, I highly doubt you have enough room presently between the mixing valve and manifold to accomplish what you need to. That means mounting the mixing valve further back overhead between the two supply feeds (back over above the first boiler with the SS impellor), and putting the 2.5/3.0 reducer further back and running 3.0 dia from there to the pump manifold. You’ll need to relocate both mixing valves.
Also, in the installation instructions there should be a section discussing piping lengths when transitioning from one size to another and how far away the fitting needs to be from the entrance side of the pump manifold.
If you don’t find it in the instructions (Might look on line at their site if you don’t have them on site) I would call tech support at B&G, and get one of their brains on the phone, and text them your pics, and see if they don’t agree with what I just said. I just looked on B&G site. It looks like they don’t make a 2.5 dia. pump. Looks like they go from 2.0 – 3.0, so you have to use a 2.5-3.0 reducer.
Copy and paste this analysis I just wrote and send it to the tech support guy in an email, so they can get their head wrapped around what I just said, so you don’t have to reread it to them.
ElkSlayer, this has been my thought also from the beginning. My hat is off to you for being so Vocationally astute in being able to describe the process of cavitation. Again, very good explanation.
Here’s the fix for you, that will save you guys a few thousand on time and material I’d bet. Just need to figure out what volume tank needs fabricated.
Instead of rerouting everything, I believe you could have a tank fabricated to put between the mixing valve and the intake manifold of the pump. Have them put a baffle on the intake side of the tank, to divert the water from just being a straight shot across the diameter of the tank, and into the 3.0 opening on the pump manifold.
Just picture a expansion tank being there.
Essentially what it would do is allow the pump to grab water out of the tank without the pressure drop immediately in the pipe at the mouth of the pump intake, as is right now. The volume of the tank would be where the pressure drop takes place.
The blue wax mixing valve is front and center. As it sits it receives hot water (165) from boiler on the left and mixes it with incoming (80) pool water on the right to send tempered water down to the pump and into the boiler.
It’s purpose is to reduce condensation in the boiler combustion chamber..
Point is it’s all 2 1/2 and is the mixing valve is supplied by the seller of these “systems”...
If you follow the pipe going away from the right side you can see back where it reduces down from 4 to 2 1/2, so in regards to increasing suction side.. it technically could be done. But I’m not convinced that would accomplish anything? post images
The 3 – 2.5 reducer on top of the B&G manifold receiving the water from the mixing valve is your problem.
It is causing a pressure drop as the water transitions from the 2.5 dia piping out of the mixing valve into the larger 2.5/3.0 reducer. The pressure drop is allowing the oxygen in the water to expand and create air bubbles as the pressure drops. It is essentially doing the exact same thing as what happens in a refrigeration system right at the metering device, where liquid refrigerant (Your case – liquid water) transitions from high pressure to a lower pressure and changes from a liquid state to a gaseous state (liquid > liquid w/bubbles > gaseous state).
Your pump is getting that (liquid w/ oxygen bubbles), and possibly a lot of bubbles.
The mixing valve is mounted too close to the pump for the water to settle back down to a solid column of water after coming out of the 3.0 dia. opening of the reducer, and before entering the pump intake. Think holding a water hose with a solid stream of water into a tank, and creating bubbles below the surface. The bubbles eventually dissipate into the surrounding water, and some rise to the surface. The pump is too close to the 2.5/3.0 reducer, and not giving the liquid enough time to settle back down.
You might need 5-10 ft of 3.0dia. transition piping entering that pump, to allow for blending back into a solid state of water after coming out of the 2.5/3.0 reducer, which would be mounted back around the mixing valve. Looking at the layout, I highly doubt you have enough room presently between the mixing valve and manifold to accomplish what you need to. That means mounting the mixing valve further back overhead between the two supply feeds (back over above the first boiler with the SS impellor), and putting the 2.5/3.0 reducer further back and running 3.0 dia from there to the pump manifold. You’ll need to relocate both mixing valves.
Also, in the installation instructions there should be a section discussing piping lengths when transitioning from one size to another and how far away the fitting needs to be from the entrance side of the pump manifold.
If you don’t find it in the instructions (Might look on line at their site if you don’t have them on site) I would call tech support at B&G, and get one of their brains on the phone, and text them your pics, and see if they don’t agree with what I just said. I just looked on B&G site. It looks like they don’t make a 2.5 dia. pump. Looks like they go from 2.0 – 3.0, so you have to use a 2.5-3.0 reducer.
Copy and paste this analysis I just wrote and send it to the tech support guy in an email, so they can get their head wrapped around what I just said, so you don’t have to reread it to them.
ElkSlayer, this has been my thought also from the beginning. My hat is off to you for being so Vocationally astute in being able to describe the process of cavitation. Again, very good explanation.
Slayer.. thanks much for the input and suggestions. I’m following along with the concept you presented of pressure drop right as the water enters the pump due to the reducer.
Keeping it simple... you are suggesting the line leaving the mixing valve to the pump go from 2 1/2 to 3 immediately after leaving the valve, and only reduce to 2 1/2 at the last minute where it enters the boiler, yes..?
That keeps as much 3” in the loop as possible allowing the water to settle..
In essence.. that deals with the cavitation before the pump, so we aren’t dealing with the effects of it after the pump...?
HC.. appreciate the input and the vids, they certainly do illustrate what seems to be happening here..even if I do have an issue completely wrapping my simple mind around the why and how.
I realize pump and flow dynamics are a whole nother ballgame
Also.. I don’t want to seem like I’m looking for the easy way out but there’s the possibility that’s what I’m going to be told to do..
Seems to me using 3x21/2 brass reducer bushings in and out of the pump flanges would greatly reduce that area of expansion being created by the 3” male adapter and fitting reducer?
The nature of the fitting would ensure a straight shot of 2 1/2 directly into the pump Just a thought...
One more thing, have the tank manufacturer use flanges with slotted holes on the tank, so you don’t have to mess with being slightly off-alignment from the bolt holes in the outer flanges you will be bolting the tank up to.
If you have it fabricated on-site, the above doesn’t matter, and that might be a quicker option to get it back together, depending on the tank fabricators workload.
The blue wax mixing valve is front and center. As it sits it receives hot water (165) from boiler on the left and mixes it with incoming (80) pool water on the right to send tempered water down to the pump and into the boiler.
It’s purpose is to reduce condensation in the boiler combustion chamber..
Point is it’s all 2 1/2 and is the mixing valve is supplied by the seller of these “systems”...
If you follow the pipe going away from the right side you can see back where it reduces down from 4 to 2 1/2, so in regards to increasing suction side.. it technically could be done. But I’m not convinced that would accomplish anything? post images
The 3 – 2.5 reducer on top of the B&G manifold receiving the water from the mixing valve is your problem.
It is causing a pressure drop as the water transitions from the 2.5 dia piping out of the mixing valve into the larger 2.5/3.0 reducer. The pressure drop is allowing the oxygen in the water to expand and create air bubbles as the pressure drops. It is essentially doing the exact same thing as what happens in a refrigeration system right at the metering device, where liquid refrigerant (Your case – liquid water) transitions from high pressure to a lower pressure and changes from a liquid state to a gaseous state (liquid > liquid w/bubbles > gaseous state).
Your pump is getting that (liquid w/ oxygen bubbles), and possibly a lot of bubbles.
The mixing valve is mounted too close to the pump for the water to settle back down to a solid column of water after coming out of the 3.0 dia. opening of the reducer, and before entering the pump intake. Think holding a water hose with a solid stream of water into a tank, and creating bubbles below the surface. The bubbles eventually dissipate into the surrounding water, and some rise to the surface. The pump is too close to the 2.5/3.0 reducer, and not giving the liquid enough time to settle back down.
You might need 5-10 ft of 3.0dia. transition piping entering that pump, to allow for blending back into a solid state of water after coming out of the 2.5/3.0 reducer, which would be mounted back around the mixing valve. Looking at the layout, I highly doubt you have enough room presently between the mixing valve and manifold to accomplish what you need to. That means mounting the mixing valve further back overhead between the two supply feeds (back over above the first boiler with the SS impellor), and putting the 2.5/3.0 reducer further back and running 3.0 dia from there to the pump manifold. You’ll need to relocate both mixing valves.
Also, in the installation instructions there should be a section discussing piping lengths when transitioning from one size to another and how far away the fitting needs to be from the entrance side of the pump manifold.
If you don’t find it in the instructions (Might look on line at their site if you don’t have them on site) I would call tech support at B&G, and get one of their brains on the phone, and text them your pics, and see if they don’t agree with what I just said. I just looked on B&G site. It looks like they don’t make a 2.5 dia. pump. Looks like they go from 2.0 – 3.0, so you have to use a 2.5-3.0 reducer.
Copy and paste this analysis I just wrote and send it to the tech support guy in an email, so they can get their head wrapped around what I just said, so you don’t have to reread it to them.
ElkSlayer, this has been my thought also from the beginning. My hat is off to you for being so Vocationally astute in being able to describe the process of cavitation. Again, very good explanation.
+100
The comparison to refrigerant through a metering device is a good one and helps with visualizing what the water is doing when it hits that 3".
Slayer.. thanks much for the input and suggestions. I’m following along with the concept you presented of pressure drop right as the water enters the pump due to the reducer.
Keeping it simple... you are suggesting the line leaving the mixing valve to the pump go from 2 1/2 to 3 immediately after leaving the valve, and only reduce to 2 1/2 at the last minute where it enters the boiler, yes..?
That keeps as much 3” in the loop as possible allowing the water to settle..
In essence.. that deals with the cavitation before the pump, so we aren’t dealing with the effects of it after the pump...?
Yeah, the problem is before the pump. You don't have enough room as it stands between the mix valve and pump to solve the problem.
Your only option is to relocate the mixer further back, and run the correct length of 3.0 dia to the pump or fab a tank. You guys will waste time and money to rig it like you're talking, and you will be back and it will damage your brand of your company. Fix it right, and be done with it. Call B&G tech, and talk to an engineer, and they will confirm my two options.
The pitting on the output will be solved once you correct the entering cavitation issue, but since you're having all of this fun, I'd put the 2.5/3.0 reducer right at the boiler intake and run 3.0 from pump to boiler.
Also.. I don’t want to seem like I’m looking for the easy way out but there’s the possibility that’s what I’m going to be told to do..
Seems to me using 3x21/2 brass reducer bushings in and out of the pump flanges would greatly reduce that area of expansion being created by the 3” male adapter and fitting reducer?
The nature of the fitting would ensure a straight shot of 2 1/2 directly into the pump Just a thought...
Nope, won't work. There is a reason it "transitions" smoothly into the impeller. Putting a 2.5 brass bushing / choke in will still create a pressure drop right at the pump when it comes out of the 2.5 opening and into the 3.0 area on the backside of the bushing.
It will also create a "void" and create even worse turbulence in the water where it should smoothly transition into the impeller.
The more I look at that pic the easier it gets. Man, have a guy come build a tank on-site. You guys provide the material. I bet a good fab guy could build both tanks in place in one day. Maybe cost you guys 3K total, tops for both.
It'd cost you way more than that rerouting and relocating the mixer. That'd be 2-3 days on each minimum, I'd bet looking at it.
Also.. I don’t want to seem like I’m looking for the easy way out but there’s the possibility that’s what I’m going to be told to do..
Seems to me using 3x21/2 brass reducer bushings in and out of the pump flanges would greatly reduce that area of expansion being created by the 3” male adapter and fitting reducer?
The nature of the fitting would ensure a straight shot of 2 1/2 directly into the pump Just a thought...
Nope, won't work. There is a reason it "transitions" smoothly into the impeller. Putting a 2.5 brass bushing / choke in will still create a pressure drop right at the pump when it comes out of the 2.5 opening and into the 3.0 area on the backside of the bushing.
It will also create a "void" and create even worse turbulence in the water where it should smoothly transition into the impeller.
Ok elk in retrospect I agree that’s true..I’ll stuff that idea back where it came from
This is a school job. Did you guys build it out as per the plans were stamped?
And where is the service manager of your company on, this? Why isn't he overseeing this to make the right decisions?
Just curious. I can't believe your company has you out on the internet looking for the right next move to solve the issue.
Fill me in. Are you the service mgr?
Damn elks.. this both made me literally laugh out loud while at the same time felt like I was getting kicked in the balls!!🤣
If you could be in my shoes you’d be laughing too. I’m just a $hithouse plumber whose problem is he cares too much about finding out the why, when something fails..
There is no service manager. If there is to be any right decisions made they’re going to made be me, with the help of you generous and knowledgeable people.
I’m on my own here. Guaranteed if I ask I’ll be told just replace the impeller and the damaged pipe. You know what I’m saying?
Also I have 23 other sites I’m 100% responsible for any and all plumbing issues, so this is taking me away from all that
Did the 2.5 flange mixing valve come with the boiler package?
Yes sir it did. A big part of my confusion here is the boiler company sells this all as a package and you would think they would have encountered these problems long before us...
Here’s what’s somewhat possible for me to accomplish...
I can 90 The two horizontal lines up as close as possible to the roof, then have them tie into the mixing valve a good 5 feet higher than where it sits. From there I can go 3 inch straight down from the mixing valve to the pump everywhere except right at the mixing valve and right into the boiler where it would obviously need to reduce to 2 1/2... it seems that would aid greatly in allowing the water to “settle” after it leaves the valve and before the pump..?
The boilers and circ pumps and mixing valve were purchased from a local boiler supply house who sells the entire package together as a unit so I have to assume things are all specd to work together. We have purchased and installed roughy half a dozen of this set up with no issues.. Pump is B&G with 3” flanges and volute. I don’t know why it’s 3” when boiler inlet and outlet is 2 1/2 but..? Male adapters and Reducers on either side of the flanges.
There is your problem. They undersized the mixing valve with a 2.5 dia model to keep the cost of the package low to be competitive, when they should've had a 3.0 flange mixing valve in the package so you have a straight shot to the pump from the mixing valve with 3.0 piping.
Their package they marketed as a complete design was flawed, because their design required a reducer that created a pressure drop, that created cavitiation that destroyed the pumps. They are fully culpable for all repair costs. Any Engineer from B&G will vouch that using the reducer caused the failure. Their design, their responsibility.
Now the other side of that coin too, is ultimately, a contractor is responsible for the final product he builds, and is licensed to know if the design is correct. So, it's really both the supply house and contractor's fault here.
You guys need to pull the 2.5 mix valves, and install 3.0 mix valves so you'll have a straight 3.0 pipe running from mixer to pump, and problem solved.
You need to talk to the tech engineer at the supply house, and explain their package they represented is flawed, and see how much they will cover in expenses for all of this. See if they will get right. It's a slam dunk win in court if you guys have to sue, being they marketed the "complete" package, instead of you walking in and ordering all of the parts separately.
Change the mixers, and go down the road, and forget the tank fix I discussed.
Come off your two feeds with 3.0 and into the new 3.0 mix valves, and be done with it.
You are in the drivers seat 100% here with the supply house, and they will know it when you start talking the technical aspects of this flawed design.
Just follow me here, and you'll get out of this all for the better. They won't screw with you, once they realize you know it is a flawed design on their part.
Also, the 2.5 mixing valve is acting as a choke in the piping, and is actually restricting the 3.0 pump's volume capacity. I don't know if your boiler's required volume is being restricted here or whether it is being compromised here, but the 3.0 mix valve will eliminate that now.
Your evidence to present to them is two points:
1 - reducer causes cavitation 2 - 2.5 mixer becomes a inline "choke" to the 3.0 B&G pump
Two points to prove their design was flawed, and that's all you have to tell them.
Their next move will determine what action your company needs to pursue if they don't get right.
I'd shoot for 100% coverage for all costs for all time, even the other trips to repair the pumps, all of it. And bill them at your going rate. Don't let them dictate what "they" want to pay. Otherwise you're just simply working at your actual cost, and not making any profit. They are responsible for lost opportunity, so you need to charge your company's normal hourly amount.
I was wondering the same. He's far more knowledgeable than this plunger jockey, that's for sure.
X2.. Elks much obliged and I’m following along as time permits here so please bear with me...
I’m picking up all of what you are putting down. A small point to make tho, I am part of the maintenance dept for our district so there are no company costs or profit per se.. but for the purpose of getting this right that is largely irrelevant.
Truth is despite how spot on you may be there’s likely little chance of “us” pursuing this as you say. Sad but true
A question then based on your observations.. Could not the same thing be accomplished by sourcing a true 2 1/2” pump assembly? B&G does not appear to make one but at a quick glance TACO does..
Assuming we don’t pursue and get compensated for a damn thing...the 3” FPE would be costly as I recall these 2 1/2 were I think over a grand each and we have 6 in the district that would ideally need to be replaced.. add fittings into that and $$
This is a school job. Did you guys build it out as per the plans were stamped?
And where is the service manager of your company on, this? Why isn't he overseeing this to make the right decisions?
Just curious. I can't believe your company has you out on the internet looking for the right next move to solve the issue.
Fill me in. Are you the service mgr?
Damn elks.. this both made me literally laugh out loud while at the same time felt like I was getting kicked in the balls!!🤣
If you could be in my shoes you’d be laughing too. I’m just a $hithouse plumber whose problem is he cares too much about finding out the why, when something fails..
There is no service manager. If there is to be any right decisions made they’re going to made be me, with the help of you generous and knowledgeable people.
I’m on my own here. Guaranteed if I ask I’ll be told just replace the impeller and the damaged pipe. You know what I’m saying?
Also I have 23 other sites I’m 100% responsible for any and all plumbing issues, so this is taking me away from all that
Don't mean to insult you at all.
I figured you were out there with your azz hanging in the wind, and that's why I decided to help you. Typical companies these days, send the guys out with no back office support.
You're a good man for caring and wanting to repair it right. Far and few in this day and time.
If your company is doing big jobs like that, and doesn't have a service mgr, then usually the owner goes out on problem jobs to oversee them, if he cares about his company's reputation.
Well, you have all the facts now, so you can relay them to your boss and he can make the right decision, hopefully. He's guaranteed to be back if he doesn't do what I said, and fix it right.
Sad, your "boss" *cough* *cough* doesn't have the answers for you.
Elk you didn’t insult me the slightest. You’d have to work here to understand the kick in the balls comment and the kick assuredly didn’t come from you😂
I was wondering the same. He's far more knowledgeable than this plunger jockey, that's for sure.
X2.. Elks much obliged and I’m following along as time permits here so please bear with me...
I’m picking up all of what you are putting down. A small point to make tho, I am part of the maintenance dept for our district so there are no company costs or profit per se.. but for the purpose of getting this right that is largely irrelevant.
Truth is despite how spot on you may be there’s likely little chance of “us” pursuing this as you say. Sad but true
A question then based on your observations.. Could not the same thing be accomplished by sourcing a true 2 1/2” pump assembly? B&G does not appear to make one but at a quick glance TACO does..
Assuming we don’t pursue and get compensated for a damn thing...the 3” FPE would be costly as I recall these 2 1/2 were I think over a grand each and we have 6 in the district that would ideally need to be replaced.. add fittings into that and $$
Ok, I hear you now, you're the maintenance for the district.
2.5 TACO's could solve your issue, "IF" they fill the boiler requirements for GPM, etc. You need to look at the specs for the boiler, to see what the MIN / MAX is, to ensure it will work. Hell call the supply house, and get them to look it up, well maybe not......you check it.
Copy that elks.. I’ll do what I can to see if boiler requirements would be met. Tho a new pump assembly would not be cheap it would be way less time consuming to do it that way.. And time is never on my side in this dept..
I didn’t want to come off as too negative while trying to paint a realistic picture of what is going on here, but yes in this case I’m wearing too many damn hats
Has it been proven that cavitation is the problem here?
IF cavitation is the problem, it might be cured by adding an inline circ p. upstream of the tee feeding the butterflys. Why? Because NPSH is all important.
Do you know many types of bronze are not compatible with chlorine?
Has it been proven that cavitation is the problem here?
IF cavitation is the problem, it might be cured by adding an inline circ p. upstream of the tee feeding the butterflys. Why? Because NPSH is all important.
Do you know many types of bronze are not compatible with chlorine?
I don’t think anything has been “proven” per se only time will tell that.. Some very good ideas that make sense to me anyway and I’m going to run with them the best I can within the restrictions I have to work with
I’ll look into this a bit and would assume it does not meet boiler flow requirements otherwise why the hell isnt this the one they supply...
This might not apply to this deal, but I'm seeing lots of mismatched packages due to COVID and supply chain problems. The suppliers can't get the correct parts so they substitute and probably figure the customer won't complain if they over-spec the substitute - in your case a 3" substitute for a 2.5" pump.
Copy that elks.. I’ll do what I can to see if boiler requirements would be met. Tho a new pump assembly would not be cheap it would be way less time consuming to do it that way.. And time is never on my side in this dept..
I didn’t want to come off as too negative while trying to paint a realistic picture of what is going on here, but yes in this case I’m wearing too many damn hats
Thanks again
Y/W, but if the 2.5 TACO wind up working w/ the specs, you solved it 100%, not me. I was concentrating on solving the pressure drop from a different angle (while multi-tasking here), and just assuming the pump had to be 3.0 to meet the specs for the boiler, and really didn't consider changing the pumps, but you still might have to stay with the 3.0 pump.
You need to look at the specs on that 2.5 mixer also to ensure it's GPM flow rate meets the boiler GPM requirements. You just don't know what is what in this situation now, when you have guys throwing packages together where they screw up the design, like here w/ the reducer to create a pressure drop. Sometimes you have to step back and reassess the complete package before moving back forward again.
If you have to stay w/ the 3.0 pump, that tank fab might still be easier, quicker, and cheaper than changing to a 3.0 mixer. You pretty much know your options now, and are back on the road to solving it.
I’ll look into this a bit and would assume it does not meet boiler flow requirements otherwise why the hell isnt this the one they supply...
This might not apply to this deal, but I'm seeing lots of mismatched packages due to COVID and supply chain problems. The suppliers can't get the correct parts so they substitute and probably figure the customer won't complain if they over-spec the substitute - in your case a 3" substitute for a 2.5" pump.
Yep, and they didn't pickup on the reducer creating a pressure drop / problem in their hurry to keep inventory turning. It happens.....more and more.
30-40 years ago, this didn't happen. People took pride in their work at all levels, and watched out for their customer's better interests. Not today.
I’ll look into this a bit and would assume it does not meet boiler flow requirements otherwise why the hell isnt this the one they supply...
yeah, that should work. The Hydronic Laws for 2.5 pipe will tell you it will flow the required amount, and I can't see B&G under sizing the HP to where it wouldn't max out the flow for 2.5 dia piping.
Probably shortages like JOG just described.
It is bad right now across all sectors. You won't here it in the news, but it is bad, and everyone in the know does not see it getting better anytime soon.
You fellas might be in over your heads here. If you don't know what NPSH is, then you shouldn't be engineering projects with delicate running parameters. There is a gross lack of info here, to include lack of monitoring devices, (thermometers, flow recorders, pressure gages, etc.), unsufficient mention of psi and temp at various points of interest, whether suction pressure is positive or negative, and what is their values, the list goes on and on.
What you need to do is not replace parts, as it will possibly repeat at a cost, but find and correct the problem.
If the owner of this site is compassionate, or has deep pockets, s/he, or they might incur the cost of refinement, as it WILL be their equipment upon completion.
You fellas might be in over your heads here. If you don't know what NPSH is, then you shouldn't be engineering projects with delicate running parameters. There is a gross lack of info here, to include lack of monitoring devices, (thermometers, flow recorders, pressure gages, etc.), unsufficient mention of psi and temp at various points of interest, whether suction pressure is positive or negative, and what is their values, the list goes on and on.
What you need to do is not replace parts, as it will possibly repeat at a cost, but find and correct the problem.
If the owner of this site is compassionate, or has deep pockets, s/he, or they might incur the cost of refinement, as it WILL be their equipment upon completion.
Just my thoughts at this point.
No sweat!
One step at a time, first solve the pressure drop, and he is working on it and I believe pressure drop causing cavitation is what NPSH is all about, correct?
Next, run the boiler and check vitals, and check the barometric.
There's no re-design going on. All specs are being looked at to meet GPM needs to all equipment.
[/quote] One step at a time, first solve the pressure drop, and he is working on it and I believe pressure drop causing cavitation is what NPSH is all about, correct?
Next, run the boiler and check vitals, and check the barometric.
There's no re-design going on. All specs are being looked at to meet GPM needs to all equipment.
[/quote]
NPSH has multiple variables; suction head pressure, TEMPERATURE, flow demands/characteristics/variables extremes, velocity, density, specific gravity, you get the idea. The product being pumped and it's chemical levels and constituency within proper parameters (i.e. no slugging).
Perhaps minor corrections can resolve this issue. However, if it doesn't, then we are just parts changers, prone to repeat a failing process.
We know that a pump has failed, piping sizing might be suspect, NPSH is currently in question, impeller might be wrong material, discharge line has deposits and leaks, hangers and saddles and supports might be in need of redesign, thermometers and psi gages are needed, etc. I have seen butterfly valves that don't open properly. Any mechanical component might fail or be compromised.
Now then, back to a question I asked earlier: does only one boiler run at a time, or two at times?
You fellas might be in over your heads here. If you don't know what NPSH is, then you shouldn't be engineering projects with delicate running parameters. There is a gross lack of info here, to include lack of monitoring devices, (thermometers, flow recorders, pressure gages, etc.), unsufficient mention of psi and temp at various points of interest, whether suction pressure is positive or negative, and what is their values, the list goes on and on.
What you need to do is not replace parts, as it will possibly repeat at a cost, but find and correct the problem.
If the owner of this site is compassionate, or has deep pockets, s/he, or they might incur the cost of refinement, as it WILL be their equipment upon completion.
Just my thoughts at this point.
No sweat!
They wouldn't listen anyway! Just keep on guessing.
I'd love to be a fly on the wall, while Certifiable is standing there,
talking to the proper personnel,
ah, ya , I need another 10 grand in material and labor,
I think I know whats going on here, and how to possibly fix it,
guy on the internet told me so..........
Should go well huh?
Well look who showed back up. Here's a troll who obviously wants to push this thread south.
Here kenneth, I'll step aside, and why don't you enlighten the audience with your brilliance on the subject matter......
No troll at all, Not sure why you went there,
I've been in Cert's situation, trying to convince management on what, I think I know what the problem is, not sure but lets throw money at it and hope for the best.....Then explaining your going by info from some guy on the 'net.....Guaranteed to raise eyebrows.
And trying to request these funds from a school board. ain't that easy. been there, done that.
For Cert's sake, I hope your right, if he takes your approach, or he's the one that will face the music.
Spoke to a B&G rep about the problem(s) and he didn’t feel the 2 1/2 reducers were the problem, but was focused more on the motor/pumps sizing. He speculated that the pump may be starving for water and causing the cavitation. Either because the pump is oversized (it’s not per the boiler GPM specs) or because of a restriction upstream.
A question then based on your observations.. Could not the same thing be accomplished by sourcing a true 2 1/2” pump assembly? B&G does not appear to make one but at a quick glance TACO does..
Assuming we don’t pursue and get compensated for a damn thing...the 3” FPE would be costly as I recall these 2 1/2 were I think over a grand each and we have 6 in the district that would ideally need to be replaced.. add fittings into that and $$
This is exactly where my mind was going—why not swap down to 2-1/2" pumps, getting rid of the reducers between the mixing valve and the pump.
I'd love to be a fly on the wall, while Certifiable is standing there,
talking to the proper personnel,
ah, ya , I need another 10 grand in material and labor,
I think I know whats going on here, and how to possibly fix it,
guy on the internet told me so..........
Should go well huh?
Well look who showed back up. Here's a troll who obviously wants to push this thread south.
Here kenneth, I'll step aside, and why don't you enlighten the audience with your brilliance on the subject matter......
No troll at all, Not sure why you went there,
I've been in Cert's situation, trying to convince management on what, I think I know what the problem is, not sure but lets throw money at it and hope for the best.....Then explaining your going by info from some guy on the 'net.....Guaranteed to raise eyebrows.
And trying to request these funds from a school board. ain't that easy. been there, done that.
For Cert's sake, I hope your right, if he takes your approach, or he's the one that will face the music.
Later.
Tell whoever complains about paying the bill that the supplier they chose provide the systems included the wrong size pump relative to the rest of the system. This is evidenced by a failure to adhere to basic design standards and resulted in the pump having failed twice in two years.
I want to think there's got to be an obvious reason why the other pump didn't get destroyed. Are both boiler systems run in tandem or do they cycle back and forth or does one run as a primary with the second only kicking in when needed?
Spoke to a B&G rep about the problem(s) and he didn’t feel the 2 1/2 reducers were the problem
He's wrong. Going from 2.5 > 3.0 will create a pressure drop, which you don't want, air bubbles.
Quote
but was focused more on the motor/pumps sizing. He speculated that the pump may be starving for water and causing the cavitation. Either because the pump is oversized (it’s not per the boiler GPM specs) or because of a restriction upstream.
That restriction would be the 2.5 mix valve acting as a choke, like I mentioned above.
Simple fix is put the 2.5 pump in (99.9% It's going to flow enough, being the intake on the boiler is 2.5, just need to check the specs), and that will solve the pressure drop from the 2.5/3.0 reducer by removing it.
Being this job was just "added possibly" to the system, "without a load analysis performed on the water supply" to ensure the two boilers running at the same time (or even just one) do not overload the supply, and create a low water pressure situation, they need to perform one to eliminate that as a cause, even with the change to the 2.5 pump. Nobody knows what systems are on that branch coming off the main at this point.
This "repair" is at the point where you need to start from the beginning (drawings), and cover all bases.
ETA: and yes, there should be test points to attach meters, or permanent installed, so you know what's going on.
You need those anyway to adjust the barometric, so you know what your changes / adjustments are doing.
With two boilers in service at the same time, might it be possible that one of them is "hogging the load" (waterflow) (NPSH), encouraging the other to be starved (low NPSH)? This being my reason for asking about multi-boiler operation.
A 2 1/2 pump assembly was ordered Thursday afternoon. The situation was explained to the best of my ability to the shot callers (mostly me?) based on the info I have gleaned from you people.. I was off Friday and the weekend. So I have severed ties with this situation till Monday.
Until then I am spending my time making this abomination to kick my nieces and nephews asses in the Easter hat making contest.. Try to control yourselves, especially you Kingston!
My experience is mostly with agricultural pumps, but am I wrong to think that this doesn't look like a pump that's been recently running constantly?
Bossman.. as was mentioned the pumps on the boilers run 24/7 even this both boilers do not. That is the stainless impeller on the pump assembly that has to date, not caused problems
Just talking here, but the stainless impeller is holding up better than the bronze one, which was destroyed
Chicken or the egg scenario but it seems likely cavitation first caused bronze impeller failure which then accelerated pipe failure downstream, make sense?
Conversely the stainless impeller is holding up better against what is most likely the same cavitation issues therefore not multiplying the effects downstream
Obviously some assumptions being made there but just a thought
Why are you running water through a boiler, when the boiler is not engaged in the process?
Why is condensation a problem while the boiler is in service, but not a problem when it is idle but with water flow?
SC I do not have a good answer for you as to why the pumps run 24/7... the condensation I mentioned was from cold pool water (80) entering the boiler tubes and being heated to 150-170..
That condensation caused premature failure of combustion chamber
It was pointed out a mixing valve was needed to temper that water entering the boiler so now it enters at approximately 130
Kenneth..we have 5 highs schools with this the only dual boiler situation. One has a brand new pool and I have not even been into the boiler room there yet so 6 pool boilers total but one unknown.
Those 5 pool boilers are RBI dominator with same FDE mixing valve and BG pump. I posted a picture earlier of another system that uses the same parts and design but the layout is different due simply to existing pool lines
To further add confusion there are 2 more of these “packages” but for domestic water heating. As they don’t deal with pool water we can probably leave those out.
I guess that’s a long winded way of saying while the packages are the same, the situations they are plumbed into, are not.
Great hat man! Having fun with your children is one of life’s greatest gifts.
Thanks sir!
Kingston this gent realizes quality and pm’d me an offer of $850. The bar has been set. No lowballers
Hey! You said you weren’t going to shop my bid. I guess I can understand it, since Kingston is Campfire Psyops royalty. I’m tapping out on this one. I bid as much as I could afford. Obviously I should have stayed on the porch. 😉😁😂
It’s well established that all Californians are wealthy real estate tycoons. Pony up Hig.
Box office earnings have been slow.
Trailer repairs high.
Beav will have to build his own hat.
You've seen Beav's stock painting? Lord help us.
Certifiable's price seemed outrageous until I realized he didn't have to come on here asking for help making it.
I think theres a plumber in the Etsÿ pile, if you catch my meaning... The man has obviously amateur modeled hats before.
Renegade will be on here momentarily with a forensic analysis of the 'fashion' photography. It's no coincidence that the bottom of the frame stops just above the nipple line.
I'll set a Gofundme up so we can get Beaver a proper hat.
Why are you running water through a boiler, when the boiler is not engaged in the process?
Why is condensation a problem while the boiler is in service, but not a problem when it is idle but with water flow?
The Start up tech wants the pump and boiler wired separately- a switch for each. Directions were that if you turn the boiler off- let the pump run for a few minutes to pull out the heat from the exchanger to keep condensation from happening.
It was explained to me as follows by the start up tech-
Condensation in the boiler doesn’t occur when you have pool (tank) temperature water running through a non ignited boiler.
Condensation would occur when you have a low inlet temp and a high outlet temp. The mixing valve brings in a set 140* water into the boiler and with a 25* delta T giving us a target temp of 165*.
Condensation is what killed the previous two raypak boilers which used a ball valve as a mixing valve.
A 2 1/2 pump assembly was ordered Thursday afternoon. The situation was explained to the best of my ability to the shot callers (mostly me?) based on the info I have gleaned from you people.. I was off Friday and the weekend. So I have severed ties with this situation till Monday.
Until then I am spending my time making this abomination to kick my nieces and nephews asses in the Easter hat making contest.. Try to control yourselves, especially you Kingston!
With a hat like that you should get a free bowl of soup!
Why are you running water through a boiler, when the boiler is not engaged in the process?
Why is condensation a problem while the boiler is in service, but not a problem when it is idle but with water flow?
The Start up tech wants the pump and boiler wired separately- a switch for each. Directions were that if you turn the boiler off- let the pump run for a few minutes to pull out the heat from the exchanger to keep condensation from happening.
It was explained to me as follows by the start up tech-
Condensation in the boiler doesn’t occur when you have pool (tank) temperature water running through a non ignited boiler.
Condensation would occur when you have a low inlet temp and a high outlet temp. The mixing valve brings in a set 140* water into the boiler and with a 25* delta T giving us a target temp of 165*.
Condensation is what killed the previous two raypak boilers which used a ball valve as a mixing valve.
So then, this moisture is being formed by what, the incoming combustion air, or by the moisture inherent to the fuel?
I think I can answer. Without a mixer, and with the boiler being underfired, moisture is falling out of the flue gas stream at the boiler outlet. This moisture enters with both the primary air and with the fuel. Perhaps this scenerio (boiler low firing rate) is utilized to increase efficiency. In a perfect world, flue gas temp would never be allowed to reach dewpoint.
Without a mixer, flue gas temp would need to be increased at boiler outlet (increased firing rate). During the off cycle, boiler would need to be "bottled up", using dampers to isolate the fireside. And, the water flow would need to be diverted away from boiler.
I would consider the need for the mixer a bandaid approach to minimize equipment at the setting.
But, this is but a small operation, so I am probably okay with it. I guess. BUT, the mixer does reduce NPSH at the pump inlet because of elevated temp.
It’s well established that all Californians are wealthy real estate tycoons. Pony up Hig.
Box office earnings have been slow.
Trailer repairs high.
Beav will have to build his own hat.
You've seen Beav's stock painting? Lord help us.
Certifiable's price seemed outrageous until I realized he didn't have to come on here asking for help making it.
I think theres a plumber in the Etsÿ pile, if you catch my meaning... The man has obviously amateur modeled hats before.
Renegade will be on here momentarily with a forensic analysis of the 'fashion' photography. It's no coincidence that the bottom of the frame stops just above the nipple line.
I'll set a Gofundme up so we can get Beaver a proper hat.
A 2 1/2 pump assembly was ordered Thursday afternoon. The situation was explained to the best of my ability to the shot callers (mostly me?) based on the info I have gleaned from you people.. I was off Friday and the weekend. So I have severed ties with this situation till Monday.
Until then I am spending my time making this abomination to kick my nieces and nephews asses in the Easter hat making contest.. Try to control yourselves, especially you Kingston!
I think I can answer. Without a mixer, and with the boiler being underfired, moisture is falling out of the flue gas stream at the boiler outlet. This moisture enters with both the primary air and with the fuel. Perhaps this scenerio (boiler low firing rate) is utilized to increase efficiency. In a perfect world, flue gas temp would never be allowed to reach dewpoint.
Without a mixer, flue gas temp would need to be increased at boiler outlet (increased firing rate). During the off cycle, boiler would need to be "bottled up", using dampers to isolate the fireside. And, the water flow would need to be diverted away from boiler.
I would consider the need for the mixer a bandaid approach to minimize equipment at the setting.
But, this is but a small operation, so I am probably okay with it. I guess. BUT, the mixer does reduce NPSH at the pump inlet because of elevated temp.
I don’t have the numbers one me....
But I don’t suspect the cooler air that could cause condensation is coming down from the flue- as it meets factory RBI specs. The flue is only a touch longer than 8ft in height, which per factory guidelines does not require a barometric damper, but one is installed to ensure the flames arent lifted too far from the burners. I’ve verified the flames look as they should .
We seem to be off topic regarding the condition of the combustion chamber/condensation/refectory cement and the cavitation, and potentially electrolysis, that’s causing the premature wear on the copper.... unless you’re sandbagging withholding information.