Heat Pump Water Heaters and A Note About Your Boiler

This is the last installment of the Water Heater Chronicles, and it covers two alternatives for providing hot water to your home. Before I go any farther, I just want to make clear that no one had Massachusetts in mind when they designed heat pump water heaters. Also, not everybody has a boiler, but if you do, you have a big ace in your domestic hot water hole, so to speak.

The Heat Pump Water Heater

A heat pump water heater takes heat from the surrounding air and applies it to stored water in a tank. Heat pump water heaters are designed to work in areas where the temperature varies from about 40°F to about 90°F, and they require about 750 cubic feet of air space around the device. (Do not install a heat pump water heater in an enclosed area, like a closet, even if the closet is louvered.) Heat pump water heaters tend to cool the space they’re in, and they don’t work well in a naturally cold space, like a basement.

Hybrid versions of a heat pump water heater include electric assist and all-electric water heating modes. Even in electric and hybrid modes, a heat pump water heater is more efficient than a conventional electric water heater. One advantage of a heat pump water heater is that they can be programmed to “sleep” during extended absences.

Heat pump systems that are designed to heat and cool homes can also be modified to attach a water heater to the existing system. Heat from the home that would otherwise be returned to the ground is diverted to a water heater instead. This approach to hot water can be used with either a storage tank or a tankless hot water system.

Massachusetts doesn’t provide the ideal year-round environment for efficient heat pump operation. In other words, you’re not likely to be happy with the results of a heat pump water heater in January. As the technology changes, heat pumps (for climate control and hot water) may become a more attractive option, but that’s not the case in 2015.


If your home has a hydronic heat system or a steam boiler, you already have a built-in source of domestic hot water. Many homes with boilers also have a water heater, which is absolutely unnecessary! The same boiler that provides heat for your home is capable of (and designed to) meet all of your domestic hot water needs. If you have a boiler, a licensed plumber can install a very efficient indirect water heater that uses the boiler to produce and store domestic hot water.

The advantage of this is obvious – you eliminate your direct-fired hot water tank altogether in favor of a heating source that’s already installed and operating in your home. Second, indirect water heaters have a long life expectancy, often come with lifetime warranties on the tank and heat exchanger, and are relatively low-maintenance devices. They have very low standby loss, which means they’re able to maintain hot water in the tank without the need to fire the boiler often. They range in capacity from 30 gallons to over 100 gallons and actually produce the highest hot water output of any domestic water heating option. In times of peak demand, you won’t run out of hot water.

Throughout 2015, Gas Networks customers can claim a rebate of $400 on indirect water heaters. You can also claim a rebate of $1,500 on a natural gas hot water boiler with an efficiency rating of .95 or better, or a $1,000 rebate on a natural gas hot water boiler with an efficiency rating of .90 or better.

If you have a boiler and a stand-alone hot water tank, and you’d like to switch to an indirect water heater that uses your boiler, call us at Boston Standard Plumbing & Heating at (617) 288-2911. We can install an efficient, high-performance indirect water heater to supply all of your domestic hot water needs. Learn more about our water heater services in Boston, MA.

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