Q. Many sources, including Consumer Reports, extol the advantages of programmable thermostats. But are they a good thing for electric heat pumps, which deliver less heat over a longer time than electric ones?—Larry Jackson, Spartanburg, SC
A. Any energy savings occur only during the setback period: about 1 percent savings for every degree difference compared with the normal house temperature. Heat-pump systems tend to have less excess capacity, and during cold weather they can take longer to recover to normal temperatures. To compensate, you can reduce the amount of temperature change, though a smaller setback means less savings.
Check our thermostat buying guide, find the best programmable thermostats, and learn more about central air conditioning and gas furnaces.
Send questions to ConsumerReports.org/askourexperts.
This article also appeared in the September 2014 issue of Consumer Reports magazine.
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