It's finally March, and the cold weather is now about as welcome as a dinner guest who decides to stay for the weekend. For many homeowners with conventional heat pumps, winter is more like the dinner guest who stayed a month. Heat pump owners often complain that their systems are costly and do not keep them warm. While heat pumps can be an excellent heating system choice, they do have some important drawbacks when employed in northern climates.

Conventional heat pumps are, essentially, air conditioners which have the ability to throw themselves in reverse cycle.

Air conditioners do not "make cold" -- they extract heat. The heat that the interior components of an air conditioning system extracts from the inside of a home is discharged as warm air at the outside (condenser) unit. When a heat pump is warming a house, it is actually attempting to air condition (cool) the outside air, and the by-product is warm air discharge inside.

This system works wonderfully well and efficiently under modest heating loads, but in many northern latitudes of the country the "reverse air conditioning" concept simply cannot deliver cost-efficient comfortable heat in the coldest winter months.

Most heat pumps in the United States are configured with some type of back-up or auxiliary heat for times when the outdoor temperatures are just too low for the real heat pump concept to work. Most back-up systems are simply electric resistance coils -- nothing more than coiled toaster burners! The electric resistance coils are very costly to operate. The primary complaint we hear about heat pumps is that the modest cost of operation for most months is more than offset by the very high operating cost in the dead of winter, a problem due usually to activation of the resistance coils.

What can a heat pump owner do to limit the activation of the resistance coils and the associated higher expense?

Most importantly, stop playing with the thermostat! Despite what may appear to be conventional wisdom, turning the heat down for a few hours can actually cost a heat pump owner more than leaving the temperature at a constant setting. Most heat pumps are configured so that the electric resistance coils are activated if the system is asked for a quick "jump" in temperature -- even if the outdoor temperatures are high enough for the system to work without the resistance coils.

The 30 cents one spouse tries to save by lowering the thermostat setting by 5 degrees, is more than consumed by the inadvertent activation of the resistance coils when the other spouse turns the thermostat back up a few hours later (Note the entirely non-gender specific nature of the analogy!) Do yourself a favor with the heat pump thermostat: set it, and forget it.

The other common heat pump owner complaint is that the unit appears to be blowing cold air. Exclusive of the times when the auxiliary or back-up system is in cycle, a conventional heat pump will deliver air that is about 16 to 20 degrees warmer than the indoor ambient air. At 68 degrees inside (i.e., when the first spouse has set the thermostat), the discharge temperature from the heat pump ducts may be as low as 84 degrees, and 84 degree air blowing across our 98 degree bodies does not feel like warm air.

There is no simple solution to this issue, but it can often be minimized by good quality ductwork which is designed to not discharge air directly over or across likely seating and bedding areas - of course changing or improving ductwork in an existing home is no easy task.

If you have a heat pump you have been displeased with this winter, take solace in knowing that summer is not too far away -- and you have central air conditioning!

For more articles by Andrew Kleeman, please press here.

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Copyright 2001 Andrew Kleeman. Posted by Realty Times with permission.

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Published: March 2, 2001

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