Where is the fan switch on a furnace?
The fan limit switch sits on a mounting plate and has a long temperature sensor that extends into the furnace plenum: an air chamber that fills with air from the blower fan. The plate has a wire that runs to the blower and one that goes to the gas valve.
How does a furnace fan limit switch work?
To put it very simply, the furnace fan limit switch is a control that tells your furnace’s fan when to turn on and off. So, when the furnace isn’t on, it tells the blower not to operate (and send cold air into your home) and when the furnace is on, it tells the blower to turn on and start circulating the warm air.
How do I adjust the fan switch on my furnace?
Check with your owner’s manual for suggested temperatures. For a general guide, set the two lowest ones (from the furthest left) to 100 and 130 degrees to control when the fan comes on and goes off. The third marker should be set around 200 degrees as a safety shut-off for the burner.
What kind of switch is the fan switch?
A single wall switch controls the power to the fan and light together, whereas a dual wall switch has two separate switches – one for the fan and the other for the light.
Can you bypass a fan limit switch?
There is no good reason for a consumer to bypass a furnace limit switch. Furnace switches are reliable, inexpensive to replace, and are designed for protection of the consumer. Bypassing a furnace limit switch or any home heating component can create dangerous safety and fire hazards.
Can you reset a limit switch?
The function of your furnace limit switch is to tell the fan when to turn off and on depending on the temperature in the home. However, for your own safety, don’t attempt to reset the switch without first consulting your furnace’s instruction manual.
Where is the reset button on a limit switch?
Reset High Limit The High Limit Reset Button is located behind the gas valve.
Why does my limit switch keep tripping?
If the air inside your furnace gets too hot, the limit switch trips to prevent overheating. 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. A dirty filter is the most common cause of airflow issues.
How do you reset a furnace after overheating?
How to Reset Your Furnace
- Turn down the thermostat to its lowest setting.
- At the circuit breaker, turn off the power to the furnace.
- If this is a gas furnace, turn off the gas supply at the valve for the main gas pipe, but leave the pilot’s gas supply on.
- If the pilot light was out, light a match to relight it.
Does gas furnace work when power is out?
For the vast majority of homeowners who use a furnace with natural gas for heat, an electrical outage means the furnace won’t work. The furnace’s safety system will not allow it to turn on during an electrical outage. It is not safe to try to rig the furnace for heating, as this can compromise health and safety.
How long should a furnace gas valve last?
Precision Temperature replaced one from the 80s about a month ago. The average life expectancy for a gas furnace, though, is around 15-30 years. If you keep up with your preventative maintenance and take good care of your furnace, there’s no reason it shouldn’t easily last to the 15 year mark.
Is a faulty gas valve dangerous?
Any boiler fault is potentially dangerous, especially any problem that relates to gas. But, when your boiler locks out due to a gas valve fault, the idea is to make your boiler safe; continued operation could mean gas is being leaked into the burner. And for this reason, you shouldn’t attempt to reset your boiler.
How much does a gas valve for a furnace cost?
Furnace Gas Valve Replacement Costs A furnace gas valve costs anywhere from $200 to $600 to replace. This part allows natural gas or propane to flow to your unit. It’s usually attached to the thermocouple for emergency cutoff when necessary.