I'm looking to heat a small house with a gas tankless hot water system. Is this a good idea?

Asked by mark
Derry, NH

I have a new 180k btu tankless hot water unit and want to know if I can also heat my house with the hot water system. The baseboard heat is the second source of heat. Heat 80% with pellets. I know I would need a heat exchanger of some sort to prevent mixing domestic hot water with heat water.


Ted Kidd

Answered by Ted Kidd

Rochester, NY

Ted Kidd Energy Guru

January 17, 2011

I would always recommend starting your home energy design process with an energy audit.

  • For example, do you have access to natural gas? If so, pellets are a more expensive form of heat.
  • The energy auditor's cost-benefit analysis of improvement options should help quantify options that are and aren't cost-effective.

Get the right equipment for the job

You really want mechanical equipment that matches your system/strategy

  • Tankless hot water units are designed to heat water from 35/55F to 115/130F.
  • Hot water boilers are designed to heat water to 170/190F. 

Combination units

There are combination (combi) type units that do both hot water and heat.

Navien, a very popular manufacturer of super high efficiency on-demand water heaters, has a combi unit that you might want to look into.


For more information:

Check out Polly Osborne's Q&A "I would like to hook up a tankless water heater to my baseboard heater to heat the house and provide hot water. Can this be done?"

Also, read Florian Speier's Q&A "Can I configure an electric tankless water heater to run a baseboard hot-water heating system?"

Tagged In: tankless, energy audit, heating cooling

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