I have some window AC units that have warning labels saying not to store them near sources of combustion like water heaters. I have a tankless combi boiler that runs on natural gas in a small room in the basement. The combi boiler is vented to the exterior wall. Is it okay to store the window AC units here?
I’m assuming that the warning labels are talking about more traditional tank water heaters which often have pilot lights, but I want to make sure.
A3 refrigerants like propane are basically dangerous. You should store them in a ventilated area away from source of flame.
A2L refrigerants are a theoretical hazard. In test, nobody has ever demonstrated flame from a leaking A2L AC unit (and they do test).
For a while, we all used non-flammable refrigerants. But they destroyed the ozone layer. So now we use various flammable or potentially flammable refrigerants.
What kind of refrigerant do your AC units contain? If it's an A3 refrigerant like propane, outside in a shed is the best place for storage. If it's an A2 refrigerant, inside a cupboard, away from heat and flame. If it's an A2L refrigerant -- not really dangerous, but a pilotless water heater is significantly more dangerous than an old-style pilot flame, that's exactly the kind of situation they are warning about.
A pilot light or flare will burn flammable gas before it builds up to dangerous levels, and requires continuous ventilation. A pilotless gas water heater will allow environment build up, and if a flammable gas mixture exists it will cause an explosion when it sparks.
