If the furnace high limit switch trips due to overheating, there is likely an airflow issue that is preventing proper air movement through the system. Check your air filter, and replace it if dirty. A dirty filter is the most common cause of airflow issues.
What causes a high limit to trip in the boiler?
What Causes a High Limit Switch To Trip? The most common cause of a high limit switch tripping is air feeding the fire, even after the fan shuts off. When the fan shuts off, your fire is raging and fires suck oxygen very powerfully.
What causes high limit switch open?
The high temperature limit switch (also known as a furnace plenum thermostat) is a safety device on a furnace that is designed to cut the gas supply when the burner temperature exceeds the safe operating range. When the temperature drops back within the safe range, it will allow the gas valve to open again.
Can I bypass a high limit switch?
Yes, you can bypass the high limit switch for testing.
Can you reset a limit switch?
You can try resetting the furnace limit switch yourself if you have a newer model by turning off the furnace for 30 seconds and then turning it back on. However, if this does not work or the furnace repeatedly shuts down, calling heating experts to reverse or reset the limit switch is a good idea.
How do you replace a high limit switch?
- Step 1: Remove the Access Cover. …
- Step 2: Locate the Limit Switch. …
- Step 3: Conduct a Voltage Test. …
- Step 4: Turn Off the Power. …
- Step 5: Disconnect the Switch. …
- Step 6: Unscrew and Remove the Switch. …
- Step 7: Install a New Switch. …
- Step 8: Replace the Furnace Cover.
What happens when high limit switch trips?
If the furnace high limit switch is tripping, it will wear out at some point. Eventually, it will trigger a lockout mode, and your gas furnace will be unable to operate until the switch is reset or replaced. Make sure you contact your technician to perform this repair task.
How do you know if a limit switch is bad?
The most common sign of a malfunctioning limit switch is the continuous operation of your furnace’s blower. Just as the limit switch won’t allow the fan to turn on until the warm air has reached the right temperature, the limit switch also shuts down when the air cools to a certain temperature.
