Heat Pump Efficiency

Old 01-26-03, 09:13 AM
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Heat Pump Efficiency

I am in need of some information. I have been told two different things in regards to heat pumps and saving energy/money. I know with traditional gas furnaces you can save money by reducing the temperature. I always thought that to be the case with any type of system. I was recently told that it actually costs less to keep the temperature of a heat pump system constant instead of reducing the temperature at night and when not needed. Does anybody know the answer???
Old 01-26-03, 09:27 AM
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i agree

by reducing the setpoint more than 3 degrees, the heat pump will play "catch up" by energizing aux heat which is generally electric strip. the added cost of using this expensive heat will off set any savings from setback. i never recommend a programmable tstat on a heat pump.
Old 01-26-03, 12:07 PM
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hvac is correct

A more than 3 degree call on your thermostat will cause the auxillary electric heat to come on. This negates the savings from turning down the thermostat at night with a heat pump because of the cost to operate the electric heat strip. It is because of this almost all manufacturers do not recommend programmable thermostats on their units.

The manufacturers responded by introducing a new thermostat. To avoid the electric heat strip from coming on, they devised a method. The thermostat when programmed will actually come on an hour before the setting and raise the temperature only 2 degrees for 10 minutes. And then another 2 degrees for 10 minutes and so on until the desired temperature setting is achieved 10 minutes before at minus 2 degrees. This progression every 10 minutes avoids the more han 3 degree call.

Honeywell makes this kind of thermostat which they call "Intelligent Recovery". White Rodgers makes one but I do not know what they call it. There are also a couple more manufacturers that make similar thermostats based on the same method.

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