Question

I would like to replace my existing oil burner with a new water furnace heat pump. I want to use existing baseboard units. Is this possible?

Asked by Tony Davis
Whitinsville, MA

House was built in 1996. Heating system is Burnham RS-11/Becket Burner. Very good insulation. Two zones -- first floor, second floor -- one pump, two zone valves.

Answer

Elliot Seibert

Answered by Elliot Seibert

Washington, DC

Everyday Green

October 27, 2010

To rephrase the question: Can you replace a boiler in a baseboard heating system with a ground source heat pump, a.k.a. geothermal?

The short answer is maybe, but it’s a bad idea. 

  • The problem is temperature. Baseboard radiators are designed to be used with very hot water that is at least 160 F.
  • Geothermal’s main strength is delivering medium temperature water at about 120 F. This is simply not hot enough for baseboard systems.
  • Some geothermal equipment can produce high-temperature water, but at a lower efficiency, thereby defeating the purpose.

To get technical for a moment, radiators transfer heat mainly by heating the air in the room by a process called convection. To do this, radiators have a number of heat transfer fins that are specially optimized for those hot temperatures. The hot fins transfer heat to the air, which causes the air to rise and disperse throughout the room. At lower temperatures, the fins do not work nearly as well, and the radiators would not be able to keep up.

That is all to say that it may be possible to replace the boiler with a ground-source heat pump, but it wouldn’t end up being much more efficient, if at all, and certainly would not be cost-effective. For geothermal, your best options are:

  • forced-air or radiant floor heating,  
  • although those are both difficult conversions in an existing home.

You might consider having a home energy audit performed by a qualified energy auditor to help pinpoint other energy-saving opportunities.

You will probably find investments that deliver more bang for the buck.

Tagged In: heating cooling, geothermal

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