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Why Won't My Furnace Turn Off?


Air quality maintenance

Why Won't My Furnace Turn Off?

If you've ever tried to turn off your furnaces, and it just won't listen, there are a few possible causes. We've put together a few things to check to discover the cause of this issue, and one possible quick fix. However, it could be a sign that your heating system needs to be inspected by a professional HVAC technician.


Possible Reasons Your Heating System Won't Turn Off

In most cases, your thermostat is the problem, not the heater. Your thermostat communicates with your system and commands it when it should run and when it should turn off. Wiring, switches, and sensors in the thermostat can fail, any of which can cause your heating system to keep running even after you've attempted to turn the system OFF.


Most heating systems have a power switch on the furnace, but it's important to address issues with your thermostat to ensure efficient heat or air conditioning operation.


Another common issue is a faulty control board. The control board is an integral part of the main heating element of your heating system. It helps to regulate the startup, run cycle, and the shutdown of a furnace. When it fails, it can keep your heating system from regulating temperature effectively.


My Furnace Won't Shut Off, Or Is It My Fan?

In some cases, the sound you're attributing to your furnace running is actually the fan. Your fan, or blower, circulates warm air throughout your home and in the cold months often runs after your furnace has completed a heating cycle. You can double-check that the problem is your furnace by turning your fan to the OFF position at your thermostat, which should cut the fan off within a few seconds. If your heat is set to OFF or COOL and the noise you're hearing stops, it was the fan running instead of your furnace.


One easy way to tell if it's your fan or furnace is to feel the air coming out of your vents. If it's cold, it's most likely your fan.


What to Do If Your Heating System Won't Shut Off

What if the air coming out of your vents is warm? In this case, the problem is more likely to be with your heating system itself. In this situation, the furnace burners aren't shutting off. While this is likely connected to a faulty thermostat or control board, there is at least one other possible explanation: a dirty filter.

A dirty filter and the resulting buildup of dust in the heating system can cause bad electrical connections, and other safety switches to trip. Try replacing your air filter and keep track of how long your system continues to run. If that doesn't resolve the problem, it's time to call a professional for service.


What If My Heating System Is Just Running Longer than Normal?

If you've noticed your heating system running longer or more frequently, you may have the same issues noted above. Another possibility, though, is leaky ductwork. If warm air is leaking as it flows through your ductwork, the normal amount of warm air won't reach the room where your thermostat is located. This will cause your furnace to keep running, working harder, and staying on longer until it can drive up the temperature to the correct setting. Leaky air ducts are often times to blame for abnormally high electrical bills.


Noble Heating can identify and repair ductwork leaks to reduce the amount of time your heating system must run to get your home to the desired temperature, and save you money.


Tired of Guessing? Call Noble Heating

Having your furnace or its blower run too often may cause unnecessary wear and tear on your system and can result in more emergency repairs and a shorter working lifespan. Our HVAC technicians can identify problems, make the fix, and help you prevent similar issues from recurring.

Don't wait for the problem to get worse. Call (503) 875-8351 or request an appointment with a technician today


David Z. | Owner

Noble Heating

Portland, OR


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