Gas and Oil Home Heating Furnaces - Gas / Electric Switch on Programmable thermostat
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gweidenh
12-23-04, 08:33 PM
Can someone tell me what difference there is between the Gas and Electric setting on a programmable thermostat?
I have a gas furnace, and just installed a programmable thermostat. I set it to Gas and noticed that the furnace would come on for 2 minutes and shut off for two minutes. Recently the outdoor temperatures have dipped to the freezing mark and the furnace would not stay on long enough to heat the house.
I switched the setting to the electric setting. Now the furnace runs for 20 minutes or so and shuts off when the temp gets to the right temp.
I am curious as too why the change in behavior between the two settings?
Also, if I may ask two questions in one thread. What is a normal air temperature to come out of a vent? The outside temperature right now is 37 degrees, and the air coming out of the vent is ~96 degrees. Is this normal? Please exuse my simple question. I am a first time homeowner and previously lived in an apartment that heat was never an issue.
I have a gas furnace, and just installed a programmable thermostat. I set it to Gas and noticed that the furnace would come on for 2 minutes and shut off for two minutes. Recently the outdoor temperatures have dipped to the freezing mark and the furnace would not stay on long enough to heat the house.
I switched the setting to the electric setting. Now the furnace runs for 20 minutes or so and shuts off when the temp gets to the right temp.
I am curious as too why the change in behavior between the two settings?
Also, if I may ask two questions in one thread. What is a normal air temperature to come out of a vent? The outside temperature right now is 37 degrees, and the air coming out of the vent is ~96 degrees. Is this normal? Please exuse my simple question. I am a first time homeowner and previously lived in an apartment that heat was never an issue.
KField
12-23-04, 08:41 PM
The gas and electric settings chance the cycle rate of the thermostat. A gas or oil system will have more mass to be heated by the fuel and will have a slight overshot on the final temperature. An electric furnace has no mass to carry the temperature upward after the call for heat.
The supply air temperature is relative to the type of system and can vary widely.
Ken
The supply air temperature is relative to the type of system and can vary widely.
Ken
gweidenh
12-23-04, 08:47 PM
Is leaving the thermostat on the electric setting ok even though I have a gas furnace?
KField
12-24-04, 12:36 PM
Yes, it is fine. I should have mentioned that.
Ken
Ken
Jay11J
12-24-04, 01:23 PM
???
What brand/model of t-stat did you get?
From what I know, Gas cycles less, and electric heat cycles more..
Something is wrong.
What brand/model of t-stat did you get?
From what I know, Gas cycles less, and electric heat cycles more..
Something is wrong.
coldmechanic
12-25-04, 10:24 AM
I agree with Jay.
The gas setting on your Tstat tells the Tstat that it should NOT send a signal to the furnace to turn the fan on - the furnace itself turns your fan on/off on a call for heat.
Your furnaces fan limit switch is funky and when the stat is set to 'Gas', the furnace fan fails to start causing the furnace to cycle on the high temp limit.
This needs immediate attention, but in the meantime the safe thing to do is to leave your Tstat in the 'Electric' heat setting so that the furnace will even work.
The gas setting on your Tstat tells the Tstat that it should NOT send a signal to the furnace to turn the fan on - the furnace itself turns your fan on/off on a call for heat.
Your furnaces fan limit switch is funky and when the stat is set to 'Gas', the furnace fan fails to start causing the furnace to cycle on the high temp limit.
This needs immediate attention, but in the meantime the safe thing to do is to leave your Tstat in the 'Electric' heat setting so that the furnace will even work.