Fact or Fiction?

The Facts About Tankless Water Heaters

Tankless, or instantaneous,water heaters are a hot topic.Tankless water heaters are about the size of a briefcase and heat water rapidly as it passes through a heated exchange coil. Proponents of tankless water heaters emphasize several benefits, but you may not be getting the whole story.


CLAIM: Huge dollar savings


  • Most tankless water heater units cost at least twice as much to purchase as standard water heaters.
  • Installation costs can be up to 10 times more than standard water heaters.
  • Tankless water heaters usually require costly new equipment upgrades for both electric and gas models.
  • The operating cost of a tankless unit is less, but the savings is only about $30 per year for average family usage.
  • Tankless water heaters significantly increase demand during peak hours, which in turn can lead to increases in electric rates.
  • Tankless water heaters are not eligible for co-op rebates or incentives.


CLAIM: Last longer


  • Tankless water heaters need very pure water or they may fail prematurely due to buildup of mineral deposits.
  • Mineral deposits can also reduce water flow and efficiency in tankless units.
  • Failure due to mineral deposits is not covered by most tankless warranties.
  • Tankless water heaters also contain many specialized parts that should only be serviced by a trained technician. Replacement parts are not readily available and usually must be ordered.


CLAIMS: Endless supply of hot water


  • ”...Taking a shower and running the dishwasher at the same time can stretch a tankless unit to its limits.”*
  • “Even the largest …model cannot supply enough hot water for simultaneous, multiple uses…”*
  • “Typically tankless water heaters provide hot water at a rate of 2 to 5 gallons per minute.”*
  • Standard water heaters have no flow rate limits!


As you can see, the high costs of purchasing, installing and servicing a tankless water heater far outweigh the modest energy savings. And even after that expense, you still may not have all the hot water you need,when you need it!


* U.S. Department of Energy: consumer/your_home/water_heating/index.cfm/mytopic=12820

“What’s the Big Deal About Tankless Water Heaters?” White paper by Dr. William Hoover, A.O. Smith Corporate Technology Center.

Tankless Electric Water Heaters, The rest of the story. Innovations, Summer 2005.