Arizona.
Gas-fired furnace left and swamp (evaporative) cooler on right. Both are on the roof.
T he gas heater will probably work beter once the gas valve is opened. LOL Not too critical on this day in that it was 101*F. Lack of humidity makes it VERY comfortable. You don't sweat at all.
Flue pipe in front of gas frunace is gas-fired hot-water heater, pic to follow..