Air-exchange heat pumps stall out at about 35F outside air temperature, so
electric resistance
heating kicks-in. If you have a ground-exchange heat pump, it works against
the ground
temperature (59F average across the US) and does not have this problem. It
thus uses a lot
less electricity (heating or cooling) but that has to be balanced against
the much greater installation
cost (buried heat exchange tubing). Last time I investigated, the
incremental cost of installing the
ground-exchange in a residential situation achieved payback in about 20
years. This is usually
considered a poor investment. With rising energy prices, the payback period
may have changed
since then.

-- Tom




"Conase" wrote in message
...
I was looking at some of the houses for sale in eastern Pennsylvania.

Since there is massive building going on in SEMI-RURAL areas for all the
NJ and
NY people currently moving there, I notice that some of the houses both
new and
old have HEAT PUMPS for their source of heat.

I have always heard that heat pumps are NOT that effective in COLD
climates.
The weather in this area can get to the 20º and below mark for long
stretches.
In a BAD year, the temps can linger at 10º for long periods of time.

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TIA