Tankless water heaters have been promoted as an energy-saving appliance. The reasoning is simple. A traditional water heater is tasked with keeping a large tank of water hot — typically at 120º F. A tankless water heater only heats water as needed.
The development of heat pump water heaters has changed that calculation. And they are the only water heaters that can earn you a 30% federal tax credit in addition to the $600 to $800 rebate earned by Xcel Energy customers. Xcel says heat pump water heaters are 65% more efficient than standard electric water heaters and can save you $900 in energy costs over 12 years.
There’s a secondary reason that I don’t like tankless water heaters. With a tank water heater (whether heat pump or conventional electric/gas), you can install a recirculation line, allowing you to have instant hot water at even the farthest faucet from your water heater.
A plumber has installed a recirculation line in every house I’ve owned for 20 years. Here’s how it works. Let’s say your water heater is in the basement and your primary bedroom is on the second floor. You might draw a gallon or more of cold water before hot water reaches your faucet. And that’s water that had been heated but cooled off sitting in your pipes. By running a return line from your sink to the bottom of the water heater, your faucet becomes the “top” of your water heater, and hot water rises to the top of the tank. Voila! Instant hot water on tap. (Note: You are saving water, too, by not running the tap until hot water arrives.)
Running that recirculation line can involve a lot of drywall opening and repair if you have a finished basement and need to snake the line through ceilings and walls to a higher floor. If you have a ranch home with an unfinished basement (no drywall on the ceiling), you’re spared this expense. It helps to save heat loss and energy if you install insulation on the copper pipes going from the water heater to your distant faucet, assuming those pipes are accessible. The return line should be PEX, which is plastic and does not need insulating.
Installing a hot water recirculation line is a job that any plumber can do.





