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Problem: Gas on furnace is shutting off after 3 minutes of burn time.

Problem: Gas on furnace is shutting off after 3 minutes of burn time

Solution: You would need to test some controls to see what the problem is. Why is the gas shutting off after 3 minutes of burn time.

I would start with testing the thermostat to make sure it is getting a constant 24 to 28 volts between the W and C (com) wires when calling for heat. If the thermostat isn’t getting 24 volts after the 3 minutes then you might try adjusting the anticipator if equipped. The new digital thermostats do not have an anticipator setting, but some of the new digital thermostats have instructions on how to adjust the thermostat to make a longer run cycle. I would suggest reading the instructions that came with the thermostat. If the thermostat is not the problem then I would suggest testing all the safety controls, ie limit, pressure switch, rollout switches to make sure they are all staying closed. Test the controls to make sure they are staying closed when the furnace shuts off after the 3 minutes. This sounds like the furnace might be overheating (going off on limit) and shutting down. This overheating could be caused by a dirty filter, dirty blower wheel, slow blower motor (could be a weak capacitor) gas pressure set to high on the gas valve, improper setting on the thermostat anticipator (if equipped), over-sized furnace (too big for your home or duct work) or a stopped up evaporator coil. Below we have two YouTube videos that show how to test a limit switch made by grayfurnaceman. Thank you grayfurnaceman! We also have another great YouTube video that shows 10 Reasons Why Furnaces Overheat made by Word of Advice TV. Thanks so much for making these informative videos!  I hope you can get the problem figured out easily.

4 thoughts on “Problem: Gas on furnace is shutting off after 3 minutes of burn time.

  1. The furnace ignitor wont light 3 or 4 .stop the ignition wont pick on the gas

    1. Hi Christina! Sorry to hear that you are having trouble with your furnace’s ignitor glowing. We have a post that explains some things you can test if you are having this problem on the following page: https://arnoldservice.com/problem-furnace-will-not-ignite-ignitor-will-not-glow/ I hope you can find and fix the problem soon! Steve

  2. My Bryant 915S model is 5 and half years old. Now it starts about 15 minutes and shut down again. It wont restart until I manually restart. There are 4 blinks either 1, 3 or 3, 1 not sure what is the problem.

    1. Hi James! I have no idea why the furnace is shutting down. I would like to suggest that you look at the blower door and see what the flash code that your furnace is sending means. That should tell you what the problem is. Sorry that I do not know the flash code for your furnace. Hope you can find the problem soon! Steve

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