For example a standard ProLine Atmospheric Vent gas water heater may have a. In addition to the height the space must also accommodate the height needed to connect a pipe on top of the tall water heater unit to the plumbing system of the home. How To Calculate Rectangle Water Tank Size And Capicity Water Tank Calculation Youtube Water Heaters for Mobile Homes. The capacity of a water heater is measured in . For a tank-style heater household size is a simple indicator of hot water needs. Ad Improve Your Business ROI - Get A Better Deal On Solar Water Heaters. Water heaters for commercial applications are available with storage capacities from 40 to 500 gal. Based on use a water heater may be classified as a commercial water heater or a residential water heater. Utility water heaters usually range in size from 25 to 19 gallons. It depends on the tank capacity source of heat burner or element and the size of the burner or element. In countries that instead use the me...