Encyclopedia & FAQ's

DIY Frequently Asked Questions / Tankless Water Heater


  • DIY Frequently Asked Questions / Tankless Water Heater')"> Can operate on either gas or electricity.
  • Tankless water heaters are small heating units that are hooked into plumbing lines and heat water only as needed. They do not store water, but heat it as it moves through the unit.
  • Larger tankless heaters are installed at the point where water enters the house; smaller units are installed at the point where water is used and require more than one in a house. Some operate on house current, others on gas.
  • Some of the larger units require different size plumbing lines and different size flue vents than do tank-type heaters.
  • If gas-fueled, the heater must be properly vented; if electric, it may need to be wired with two units in series which may not be practical for existing home wiring. Larger units require a 220V or 240V line. Smaller units will operate on standard 110V lines.
  • Tankless heaters are more expensive than tank types. However, they do produce savings in annual energy consumption and cost.
  • Although tankless heaters will deliver continuous hot water, they are limited in quantity. The central units cannot support hot water demands from several points at the same time; obviously, the smaller units will heat water delivered only at the points where they are installed.
  • Because of the high initial cost and the fact that American consumers are not used to the limitations these heaters place on the availability of hot water, their recommended use is to supplement existing tank-type heaters or in summer homes or locations where demand for hot water is light.