06-11-2013, 02:15 PM
quote:Hmm, I hadn't thought about that. My heater ran off a 5 gallon tank and for the most part it had no problems, but occasionally the heat would abruptly drop off in the middle of a shower. It would come back on quickly, and if I ran out to check it the flame was always still on, but perhaps there was a drop in the amount of gas available. It almost always happened at night.
Originally posted by MarkP
If you read on the internet the concern is often raised about using too small a propane tank. The propane is stored as a liquid but must evaporate before it leaves the tank. In doing so it cools the rest of the tank. Heat must be conducted into the remaining liquid from the ambient environment. As the liquid in the tank shrinks to a mere puddle in the bottom the surface area of the blob of liquid decreases until the heat transfer can't keep up. For very high demands even a relatively full 20 lb tank doesn't provide enough surface area or so I have read.
Also, I would expect that this would be more likely to happen with a full tank than an empty one, where there is more liquid needed to conduct heat and less space to store evaporated gas.