mr_andyj wrote:
Nobody answered your question. lol.
You can go a month or more if all you do is use propane for the fridge. You might go a month using propane for fridge and the stove. It is the water heater and the furnace (not needed in summer) that gobble gas.
Don't keep the water heater on all the time, just turn it on, heat water, use, turn it off.
There are devices that pair the AC units so that only one will run the compressor at a time. so, both AC units are on, always blowing fan air, but only one is actually running the AC compressor at a time. This is all I know as I have never had two.
You might be out of time to try to investigate and install this for your upcoming trip.
Propane for a fridge is literally about the size of a candle flame. You will not use much propane at all. It is not even worth posting a forum question because it uses so little propane.
You say to turn the water heater on, use the water and then shut it back off. You also say that the propane for the fridge is the size of a candle flame. But, once the water gets up to tempature the size of the flame on the water heater is only the size of a candle too !!
I suppose you could argue that eventually; even though it's insulated; that the water in the water heater will cool off and then the flame will kick back on at full intensity to heat it back up.
But,,, letting the water cool all the way back down to full cold by shutting the water heater off are you actually using more propane in the long run by forcing it to come up from full cold back up to full hot every time ??
Or, is it better, and more efficient, to leave it on and let it kick on and off once and awhile to keep the water up to temp ???