How many square feet can I heat with a std. water heater?
A. There are many variables that dramatically affect heat loss, but here are some general guidelines, based on a new construction radiant slab, very well insulated (walls, ceiling and under slab), in a mild to moderately cold winter climate area using a thermostatic mixing valve: A standard 50 gallon electric water heater with (2) 4500 watts elements and a 20 gallon per hour (gph) recovery rate can usually heat about 250 sq ft. A standard 40 gallon gas water heater with a 40,000 BTU burner and a 40 gph recovery rate can usually heat about 500 sq ft. These square footages can generally be doubled for “partially heated” areas where a 50 to 60 degree inside temperature is acceptable on the coldest days (very common for garages, workshops and storage buildings).
