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Why Won’t My Heater Stop Running?

question-mark-badgeWhen you set your furnace or other home heating system to come on, and then nothing happens, you’ll instantly know you have a problem. It might be a simple issue, like a tripped circuit breaker or clogged air filter. It could a more serious malfunction, and in that case you’ll need the assistance of HVAC professionals to inspect and repair your heating in Fresno, CA or elsewhere in the Central Valley.

There’s a flip side to this: a heating system that comes on and won’t shut off. When this happens, not only will the heating system waste immense amounts of energy and risk suffering permanent damage, but the house can become overheated, stuffy, and unpleasant. Why does this happen? What can be done about it?

Common reasons for a non-stop heating system

First, let’s clarify that when we talk about a heating system that won’t stop running, we’re usually talking about the blower fan. Furnaces and heat pumps both use a blower fan to circulate air through the interior of the heater (where the air receives warmth) and then through the rest of the house. The blower fan makes the most amount of sound in the heating system, so people usually consider a heater to be running when they hear the blower fan turn on.

Why might the blower run non-stop? There are a few possibilities once you’ve determine the issue isn’t something basic like a mis-set thermostat where the fan is set to “on” rather than “auto.”

  • Fan limit switch malfunction: The fan limit switch in a thermostat may include an override switch to keep the fan running manually. A malfunction with the thermostat may put the fan on manual override, keeping it running without stop.
  • Thermostat miscalibration (“ghost readings”): This is when a thermostat in the house is reading the temperature lower than it actually is causing it to keep the heating system and blower fan running continuously. This may be due to poor thermostat placement (such as near a draft). Professionals can recalibrate the thermostat so it makes the furnace behave correctly.
  • Short in the control board: Electrical faults lurk behind many home heating problems—and this does apply to natural gas furnaces, which have important electrical components in them, such as the fan motor. The control board for the heating system could have a short, leading to the motor or the burners to continue to run.
  • Fused contact: Another common electrical issue that will keep a motor constantly running.

These repairs require HVAC professionals

Adjusting a thermostat or replacing a clogged air filter are simple jobs you can do on your own. All other repairs, from thermostat rewiring to fixing the control board, must be handled by HVAC professionals. In some cases, there are risks from electrical shock. With natural gas furnaces, the safety risks for amateur work are even higher. Make sure you trust any heating system repair work to licensed HVAC professionals who can complete the work fast, accurately, and safely each time.

Purl’s Sheet Metal & Air Conditioning serves the Central Valley. Quality Is the Cornerstone of Our Success Since 1952!

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