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Electric Heat Pump vs. Energy Efficient Furnace

  • Transcript

    LESLIE: We’re going to Pennsylvania next and talking to Bob with an HVAC question. What’s going on?

    BOB: My house is only three years old but I have an 80-percent furnace with natural gas.

    LESLIE: Mm-hmm.

    TOM: OK.

    BOB: And I was curious to know if it’s a wise thing to do to put a heat pump in instead of my air conditioner and use the gas as the backup or if it made better sense to go with the 95-percent efficient furnace and leave the AC. I was going to consider doing one or the other or just leaving it alone.

    TOM: Well, in your part of the country – are you talking about electric heat pump?

    BOB: Yes.

    TOM: In your part of the country, with the dramatic temperature swing that you have in Pennsylvania, I would never recommend an electric heat pump because it can – if it gets to the point where it’s not going to keep up it’s always going to bring on the backup. I just don’t think that’s necessary. I would recommend that you go with a very high efficiency condensing furnace – you know, like a Lennox Pulse or something like that – and that’s going to give you the best efficiency. And then with an Energy Star-rated air conditioning compressor, those would be the two elements that would deliver the best overall efficiency in your part of the country.

    Heat pumps are generally OK only if you live in the south; like I would say Georgia and farther south because the temperature is not quite as dramatic and it’s OK if you running the backup mode from time to time. But I think in your place I would definitely use a high-efficiency furnace.

    BOB: OK. I appreciate that because it was described to me that the heat pump would only run down to about 40 degrees which is the temperature range, like you said, down south is when they are efficient and then, you know, then it would switch over to the gas. So I didn’t know if that made enough sense with the amount of time that (inaudible).

    TOM: (overlapping voices) Well what happens is – what happens is this. A heat pump is an air conditioner that runs in reverse. You know when you have a window unit stuck in a window of your house it blows hot air on the outside?

    LESLIE: Mm-hmm.

    TOM: Well, if you reverse that refrigeration cycle you have a heat pump. The problem with a heat pump is it will only heat to within two degrees of what you set it at. So let’s say you set the temperature in your house at 70. If the temperature falls to 69 the heat pump kicks on. If it falls to 68 the heat pump stays on. If it falls to 67 the heat pump says, whoa, I can’t keep up with this anymore and brings on the backup heat which, in most cases, is electric which is really crazy and, in your case, would be gas. So you’re going to end up running the gas when furnace a lot anyway. That’s why I think the best thing for you to do is to skip the heat pump part of this and just go with a good-quality, high-efficiency gas furnace. That’s going to give you the best return on your investment and it’ll also be more comfortable …

    LESLIE: Keep your energy bills down.

    TOM: Yeah, because another common complaint of heat pumps is that they blow “cold air.” But they don’t really blow cold air but they don’t blow air that’s as warm as what you’re used to. So as you’re sitting in your easy chair and that air comes out of the register at like 90 degrees instead of like 105, as it blows across your skin, your skin being damp, you get evaporative cooling which forces sort of a chill effect and that’s why people say it feels like it’s cold air when it’s really not. But for all those reasons I would not do a heat pump in Pennsylvania. I would go with a high-efficiency gas furnace.

    BOB: Thank you so much.

    TOM: You’re welcome. Thanks so much for calling us at 888-MONEY-PIT.

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