How long will it run on a set of D cells? Without the fan, will the heat spread enough to heat a 160 sq ft room with fairly poor insulation?

It'll heat way more than 160 sf.

I used the D batteries some, but it heats fine without the fan.

I did get a hose and ran it on a bigger propane bottle though. Two of the little bottles would run maybe 8 hours with both burners going, so it was handy to use a bigger bottle.

thanks. Will it run at high altitude, say 8k? I've heard that they don't work that high.

Don't know about @ 8000ft but mine works great in my noninsulated work shop.

Seemed to work for me at high altitude just fine. I used it in a 40' 5th wheel RV. Plenty of heat.

I've never had it in my plane, but it works good in the trailer.

I've used the little buddy heater at around 8K' with no issue's. It was running off of a larger 20 pound tank.

Had to goggle it. Yes it ought to work just fine I have used a different brand of Catalytic Heater in a small trailer as well as a larger one in my shop/garage. Just remember to run it in a well ventilated area as that type of heater uses the oxygen in a non ventilated area and death can and has occurred.

As a side note forget the D cell fan and get a Heat-Powered Stove Fan. No batteries needed.

I use the Big Mr. Buddy to help heat our 16 X 20 Outfitters tent. We camp around 9,000' and it works fine. The batteries last two to three nights, but I stopped using them because it puts off enough heat without the fan.

That's why the Buddy heaters have low oxygen shutoffs, and is why they sometimes have troubles running at high elevations.

Between the low O2 shutoff and if you use a CO detector, they're actually pretty safe. I used a Little Buddy for years with great success before it quit working. It needs a new burner pad and they cost more than 2/3 the price of a whole new unit. I'll just get the Big Buddy and be done with it. I can use the extra capacity on occasion.
If you leave the pilot running, it's very quick and easy to just turn up the heat without all the screwing around to ignite it.

I have one, the batteries last several hunts but I don't run the fan all night generally. Few hours at night and then in the morning for awhile. It heats my 200 sq ft tent very well without the fan but the fan is nice. They are supposedly very safe but I still only run it part time, plus it'd be too hot running all night. It's been a great heater for me. I have not had mine at 8000ft though.

+1 on all counts.