Heat Pumps

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Beginning in the 1970’s air-source heat pumps came into common use.  They have the advantage of no combustion, and thus no possibility of indoor pollutants like carbon monoxide.  Heat pumps provide central air conditioning as well as heating as a matter of course.  And they are installation-cost competitive with a central combustion furnace/central air conditioner combination.

Heat pumps operate by moving or transferring heat, rather than creating it.  During the summer, a heat pump captures heat from inside a home or business and transfers it to the outdoor air through a condensing unit.   During the winter, the process is reversed.  Heat is captured from outdoor air, compressed, and released inside.

Much less electricity is used to move heat rather than create it, making heat pumps more economical than resistance heating.  However, in all but the most moderate climates, the heating ability of the heat pump is limited by freezing outdoor temperatures.  So, electric resistance heat is used to supplement outdoor-air-source heat pump during the coldest weather, preventing “cold blow.”

Depending on climate, air-source heat pumps (including their supplementary resistance heat) are about 1.5 to 3 times more efficient than resistance heating alone.  Operating efficiency has improved since the 70s, making their operating cost generally competitive with combustion-based systems, depending on local fuel prices.  With their outdoor unit subject to weathering, some maintenance should be expected.

Carbon Monoxide

When inhaled, carbon monoxide interferes with the delivery of oxygen throughout the body, and can cause unconsciousness and death.  Even all amounts of this colorless, odorless gas cause symptoms ranging from headaches, dizziness, weakness, nausea, confusion, and disorientation to fatigue.  Prolonged exposure may cause permanent brain damage.  Children, pregnant women, the elderly, and people with anemia or with heart or respiratory problems are especially sensitive to carbon monoxide exposure.

Over 1,500 people die and over 10,000 reportedly take ill from carbon monoxide exposure each year.  Many carbon monoxide poisonings are not detected, as doctors confuse its symptoms with influenza or food poisoning.

The U.S. Consumer Product Safety Commission and others recommended the installation of carbon monoxide detectors, although it is not clear that detectors will protect consumers from low levels of carbon monoxide over long periods of time.  Detectors have also been the subject of recalls by their manufacturer due to failure to alarm at dangerous levels of carbon monoxide.

Carbon monoxide is an insidious killer.  To help assure safe operation, combustion-based heating systems should be checked frequently for indoor air pollution hazards.  Other sources of carbon monoxide, such as barbeque grills and automobiles, should never be operated in enclosed spaces.