Heat pump vs. Radiators - Opinions/Recommendations

rflail

Hello,

We bought a house (~60 years old with little insulation) a little over a year ago outside of Philadelphia. The house did not have AC or duct work and was heated by a gas-fired boiler with radiators. The boiler is about 5 years old and I was told by an HVAC installer that it is the highest efficiency you can get for a non-direct vent unit (can't remember what he said it was but think it was like 85-90%). This past Spring we had duct work and a heat pump installed (15 seer, 8.8 hspf). Now that we're heading into the winter, we are trying to figure out the best way to heat our house. We prefer the feel of radiant heat, but I think it will probably be cheaper to heat the house with the heat pump until the outdoor temperature is down around freezing (is this a correct assumption?). Also, the radiators tend to heat both the upstairs and downstairs pretty evenly, while the heat pump usually heats the upstairs about 3 degrees higher than the downstairs. For now I'm thinking about using the heat pump when we are asleep or at work and then using the radiator during the time we're awake and at home. When the temperature is consistently near freezing (Jan/Feb) I would then switch over entirely to the radiators.

I was wondering what everyone's opinion is on this and if anyone has any recommendations? I guess i'm trying to find an optimal balance of comfort vs. cost/efficiency. Any help you could provide would be appreciated.

ridgevilleac

I would conduct a test. In Jan. Run the heat pump. In Feb. run your boiler. Compare elec. bills and I would bet the heat pump will be more economical. I assume you have aux. heat strips in the new unit. Heat pumps have come a long way.

hvactech126

Run your heat pump down to freezing, and only use that. Below freezing, switch to boiler. Your over heating upstairs because it is forced air. Yes, Boiler is more even heat, but costs much more to heat home with out a doubt!

rflail

Thank you for the responses. The heat pump does not have any type of aux heating source.....we didn't get it because we have the boiler/radiators. Does my logic make sense that using the radiators only when we're at home and awake and using the heat pump when we're asleep or at work make sense as being more efficient/cheaper (compared to just using the radiators all the time)? Basically this would result in like 5-6 hours a day on weekdays that we would be using the radiators. We could use the heat pump all the time, but we really enjoy the added comfort of the radiators. Thanks again.

hvactech126

there is a thermostat you can use that would accommodate using the boiler as necessary so you keep heating, it controls both heat pump and boiler, difficult to wire, ask a contractor!

beenthere

Your idea makes sense.

In Jan and Feb. the heat pump may not keep up, depending how warm you want to keep it while your asleep.

Do you have 1 or 2 thermostats. As in, one to control the heat pump, and one to control the boiler. Or does one thermostat control both.

rflail

I have 2 thermostats...a standard programmable for the the boiler and a bryant evolution model (same as carrier infinity) for the heat pump which is supposed to be top of the line. It would be nice if the evolution thermostat could control the boiler as well and switch between the two based on the outdoor temperature (which it can read from the outdoor heat pump unit).

beenthere

In Jan and Feb. With your current set up. You can set the thermostat for the boiler 2 degrees or so cooler then the heat pump. That way if the heat pump can't keep up, it won't get too cold.


And i believe you'll find that with the use of a NAM/NIM, the Evolution control can control your boiler also. I could be wrong. Ask your contractor that installed teh heat pump about it.