Heat Pumps and Electric Heating - Electric heat cycling and efficiency
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jerry814
12-09-05, 04:36 PM
hi all,
i have a central electric heater that is housed in the same exterior unit as my a/c. i don't know much about naming terminology, but it's the kind that has heating coils right before the ductwork where the air exits the a/c/heat unit. i know this because i had to replace that ductwork recently when rita blew it off the unit.
right now, with a new digital thermostat (honeywell 7400D), the heat generally comes on every 4-6 minutes, stays on for 3-5 minutes, off for 4-6 and so on. this seems like too often to me, because i would think that by the time the heating coils are actually warm enough to be blowing warm air, the heater is turning itself off again. i'm basing this on the amount of time it takes an electric range or toaster to heat up, and also to cool down. so i guess, i'm also wondering if heat is being lost by turning off the fan before the heating coils have radiated all of their heat. i can hear the thermostat click when it calls the heat or turns it off, and it turns it off about 30 seconds to 1 minute (haven't timed it precisely) before the fan turns off.
now, granted, the temperature is being maintained at exactly what i set it at, but i'm still wondering if it wouldn't be more efficient to let the house get a few degrees cooler than it's set at, and then have the heater run for 15 minutes instead of 5. i know i can set the Heating Cycle Rate to affect how often the heat comes on, but i'm wondering if doing so will actually save energy.
any thoughts?
i have a central electric heater that is housed in the same exterior unit as my a/c. i don't know much about naming terminology, but it's the kind that has heating coils right before the ductwork where the air exits the a/c/heat unit. i know this because i had to replace that ductwork recently when rita blew it off the unit.
right now, with a new digital thermostat (honeywell 7400D), the heat generally comes on every 4-6 minutes, stays on for 3-5 minutes, off for 4-6 and so on. this seems like too often to me, because i would think that by the time the heating coils are actually warm enough to be blowing warm air, the heater is turning itself off again. i'm basing this on the amount of time it takes an electric range or toaster to heat up, and also to cool down. so i guess, i'm also wondering if heat is being lost by turning off the fan before the heating coils have radiated all of their heat. i can hear the thermostat click when it calls the heat or turns it off, and it turns it off about 30 seconds to 1 minute (haven't timed it precisely) before the fan turns off.
now, granted, the temperature is being maintained at exactly what i set it at, but i'm still wondering if it wouldn't be more efficient to let the house get a few degrees cooler than it's set at, and then have the heater run for 15 minutes instead of 5. i know i can set the Heating Cycle Rate to affect how often the heat comes on, but i'm wondering if doing so will actually save energy.
any thoughts?
airman.1994
12-09-05, 06:24 PM
Your HVAC guy should be able to set the stat up or put a time delay on it!
jerry814
12-11-05, 08:07 PM
thanks for responding airman, but the thermostat setup isn't what's troubling me. i'm more looking for general info on how long it takes the heating coils in an electric heater (central air) to warm up and cool off, and thus whether it's more efficient to have the heater run at fewer cycles per hour, but stay on longer. (ie 15 on/15 off vs. 5 on 5 off).
any thoughts anyone?
any thoughts anyone?
airman.1994
12-11-05, 08:42 PM
Electric is 1 to 1 their will be no difference