If its $35^{\circ}\text F$outside, Will my electric heat come on more often to maintain a room at $78^\circ \text F$ compared to $65^\circ \text F$? Not including the initial time it takes to heat the room to the temperature.
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$\begingroup$ It will either come on more often or come on at the same frequency but blow hotter air. $\endgroup$– G. SmithCommented Dec 14, 2019 at 17:24
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$\begingroup$ Just look at the limiting case if the temperature inside is 35 F. How much will the heater come on? $\endgroup$– Chet MillerCommented Dec 14, 2019 at 19:30
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2 Answers
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All other things being equal, the rate of heat transfer for conduction and convection is proportional to temperature difference. So the rate of heat loss to the outside will be greater maintaining the room at 78 F than 65 F and you will use more electricity.
Whether that means the heat will come on more often or with higher temperature will depend on the type of system.
Hope this helps.
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Your question can be taken two different ways but either way the answer is yes. (1) if you are comparing outdoor temperatures of 35 and 65 then the colder it is outside the more heat loss you have and the system needs to come on more often to maintain a warmer temp. (2) if you are comparing indoor setpoint temperatures of 78 and 65 then again the system needs to come on more often to maintain a warmer temperature if it’s colder outside.
answered Dec 14, 2019 at 17:32
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$\begingroup$ I guess I should have asked this differently. I have a electric baseboard heater in a room. The outside temperature is 35 deg. Will it take the same amount of time to go from 66 to 68 as it would take to go from 76 to 78. And then, when the heater is off, will the temperature drop from 68 to 66 at the same rate as 78 to 76? Thank you all for you answers! $\endgroup$– tomCommented Dec 14, 2019 at 21:16
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$\begingroup$ @tom Now you are getting into another area. Heat loss depends on the amount of insulation or exposed walls to the outside etc. $\endgroup$ Commented Dec 14, 2019 at 23:07
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$\begingroup$ Its the same room, so the insulation and exposed walls etc are the same. I'm just wondering if my heater will come on more frequently if I maintain the room at 78 compared to 68. NOT counting the time it takes to reach the desired temperature. My thought was that heat escapes at the same rate regardless of temperature if all of the other variables are the same. So once I get past the initial cost of increasing the temperature the extra 10 Deg, my heating cost should be the same at 78 compared to 68 because its only maintaining heat. I wasn't sure if there's something else i'm not considering $\endgroup$– tomCommented Dec 16, 2019 at 14:11
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$\begingroup$ The bigger the differences is between inside and outside temperatures the bigger the heat loss. The bigger the heat loss the faster it goes. So your furnace will come on more often to maintain a higher temperature difference. $\endgroup$ Commented Dec 16, 2019 at 15:30
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