Had one in college back in the 80's. Moved to a different apartment and had filled it that day.
That night, it felt a little cool, but not bad, so I went to sleep.
Woke up in the middle of the night and I swear my body temperature was 80 degrees! Lol
Slept on the couch the rest of the night and waited for the heater to warm that water to a suitable temperature.
