Can Someone Explain What A "Heat Pump" Is?
I'm considering replacing my 25 year old HVAC gas, forced hot-air system (I live in Central, New Jersey) because I think it's probably inefficient and unnecessarily expensive. I also could use an air filtration system as part of the total package because I get lots of dust in my home. Anyway, I keep hearing about "heat pumps" and was wondering how they differ from conventional furnaces and what the advantages and disadvantages are? Any comments would be greatly appreciation.
Answer:
A heat pump is a noisy device that cosumes 1/3 the energy when running as a NG furnace but it runs 3 times as long and breaks every year or so. When they break the HVAC guys gouge you bad. The only salvation is that it reverses as air conditioning in the summer. This is a "no brainer". If your lucky enough to get NG and don't need air in the summer than go with a conventional NG furnace. But...but...nobody answered his question. A heat pump is a mechanism for extracting heat from one place and depositing it in another. Common examples are refrigerators, which extract heat from their interiors and deposit it in your kitchen, and air conditioners, which extract heat from your room or car and deposit it outside. Consider a window air conditioner mounted backwards. It would attempt to extract heat from the outside air and deposit it in your room. That is exactly what a domestic heat pump does when it is asked to heat. Of course, when it is asked to cool it does the reverse. The sticker is that extracting heat from air gets harder as the air has heat less to extract. With an outside air temp of about 60 deg F, the cost of heating is roughly comparable to that of using gas or oil. But when it is below about 30 deg F, it is sufficiently hard so that it takes about the same amount of electrical energy to bring in one hundred watts of heating as if the electricity were simply used directly to run a 100 w light bulb. (That's about three times the cost of fetching 100w of heating when the outside air temp is 60 deg F.) In other words, heating with a heat pump gets less efficient the more you need it. Usually, this "flaw" is remedied with a backup source of heat, the simplest being electrical coils. The win in all this is that you get air conditioning in the summer, but it may be considerably less expensive, both initially and in running costs and repair costs, to stick with the conventional heating and air conditioning systems used in your geographic zone. The best heat pump economy is achieved in more temperate areas than NJ, e.g., NC. Note also, that a backup generator is not likely to be able to run your heat pump system when an ice storm takes out the power lines, whereas it could probably run the electrical components of a gas or oil-fired heating system.