HVAC: Pros and Cons of Heat Pumps 2

[pmkPE]

I have a few questions regarding the use of heat pumps in northern homes.

My wife and I are currently interested in purchasing a house that has approximately 2000 SF living space and is a multi-story/split level arrangement. The curious thing about this home is that it used to have a gas furnace. Now it has two heat pumps which I am assuming support different areas of the house. We did not get a chance to ask the owner (and his real estate agent, the lister, seems to be only interested in selling not explaining). I was wondering if you could give me the pros and cons on heat pumps particularly with respect to heating in the winter up here (Pittsburgh Pennsylvania). I saw the electric bills for the home which show the monthly kilowatt hours used and during the summer they are extremely low while the peaks in Dec., Jan and Feb are 2.5 - 3 times as high. Is there a potential problem with heat pumps when the temps drop below a specific temperature? Should we be concerned. It appears that the owners monthly electric bill averages $125/month (he uses an average billing that lowers the peak winter charges against the lows of the summer months).

Any input and/or advice would be greatly appreciated.

 

[CESSNA1]

PMKPE:

It appears that what the house has is a zoned system. One heat pump probably handles the daytime living area and one handles the nighttime sleeping area. Heat pumps are usually only recommended for moderate climates with low electric rates (rare now). They all have supplemental heat which usually is electric heating coils. As the temperature drops to around 40 degrees F the heat pump (which is basically an air conditioner installed in reverse) cannot supply enough heat, so the electric heat is switched on. Sometimes the utilities give special rates to people who use a lot of electricity. You may wnat to check on that. Primary energy sources such oil, gas and coal are always cheaper than the secondary sources (electric) You may want to negotiate the cost of converting it back to gas into your offer.

You experience with the real estate agent is typical. Virtually all are technical zeros. That is why they sell real estate (and fast food).

Regards
Dave

 

[MintJulep]

The biggest pro for heat pumps is that they are cheap for the contractor or builder to install. On a new home, all of which have central cooling these days, the buidler essentially gets the heating system for free.

If the house you are looking at originally had gas forced air heat, and is older, it is likely that it did not originally have central air. When the current owner either wanted to add central air, or needed to replace the furnace, he probably got "sold" on a heat pump.

A new heat pump, in a well insulated house, will do a reasonable job without suplemental heat down to an outside temperature of about 30F.

Much of the cost of any heating system depends on occupancy habits. Is someone home all day, or does everyone in the family work or go to school? What about the current owner?

 

[pmkPE]

The current owners work during the day. If we purchase the house, there will be someone home during the day.

 

[MintJulep]

Then it will cost you more to heat the house than it cost them.

It would not be particularly difficult to calculate how much more, but you would need access to information that you are unlikely to get.

 

[pmkPE]

Thank you for your time and expertise, I sincerely appreciate your efforts. :>)

 

[jpankask]

Something to think about, from an ex-heat pump user; the electric back-up heat system found on most heat pumps creates very dry air in the house. It gets particularly bad when it is very cold outside and the electric heater is running a lot. You will find that as your air gets more dry, the house seems colder than the temperature shows it to be. Consequently, you will end up cranking up the heat a few degree higher than you normally would if the humidity was 50%-60%. With someone home all day, that could translate to much higher heating bills in the winter. You might check into whether you can add a humidifier to your air handler or whether there already is one.

 

[GBAILEY]

You could also add a high efficiency condensing gas furnace and a fossil fuel kit to cut out the HP at low temperatures and use gas heat. This option would obviously have to be examined in light of local gas and electricity rates vs first cost to determine if it's a viable option for decent payback.

 

[DUMechEng]

how does electric heat cause the space to be any dryer than other forms of heating?