What To Know
- It is important to test the limit switch on a regular basis to ensure that it is functioning properly and that the furnace is operating safely and efficiently.
- The plenum chamber is the hottest part of the furnace, so the limit switch is designed to activate when the temperature reaches a preset limit.
- The limit switch is typically located on the blower fan or heating element and is designed to turn off the power to the furnace….
If you’re a homeowner who likes to DIY and take care of your own furnace maintenance, one of the tests you should know how to do is testing your electric furnace limit switch. This switch is there for a good reason: it protects the heat exchanger from overheating and damaging itself.
Where and How to Test
The limit switch will be attached to the furnace’s access panel, and it will have a wire running to it. There will be a button that activates the switch. To test it, simply press the button. If the furnace starts up, then the switch is working. If it doesn’t, then the switch is bad and needs to be replaced.
How to Replace the Switch
If you’ve determined that the limit switch is bad, the good news is that it’s relatively easy to replace.
How To Test Electric Furnace Limit Switch
Testing a limit switch on an electrically heated furnace is a straightforward process that can be done with a few basic tools and a little bit of knowledge.
First, you will need to gather the following tools: a multimeter, screwdriver, and wire strippers.
Next, you will need to locate the limit switch on the furnace. This switch is usually found near the heating elements and is used to turn off the power to the heating elements when they reach a certain temperature.
Once you have located the limit switch, you will need to use the wire strippers to remove the wires from the switch. Be careful not to damage the wires or the switch.
With the wires removed, you can use the multimeter to test the switch. Set the multimeter to the ohms setting and touch the probes to the two terminals on the switch. The multimeter should read a resistance of close to zero ohms if the switch is functioning properly.
If the switch is functioning properly, the heating elements should turn off when the temperature is reached. If the heating elements do not turn off, the switch may be defective and you will need to replace it.
It is important to test the limit switch on a regular basis to ensure that it is functioning properly and that the furnace is operating safely and efficiently.
What Is The Purpose Of An Electric Furnace Limit Switch?
- 1. Electric furnace limit switches are used to automatically shut off the furnace if the temperature gets too hot.
- 2. This helps prevent damage to the furnace and reduces the risk of fire.
- 3. Limit switches are also used to prevent the furnace from overheating and to protect people from burns.
- 4. These switches are typically installed in the furnace’s plenum or plenum chamber, which is the area between the furnace and the air ducts.
- 5. The plenum chamber is the hottest part of the furnace, so the limit switch is designed to activate when the temperature reaches a preset limit.
What Are The Symptoms Of A Failing Electric Furnace Limit Switch?
The symptoms of a failing electric furnace limit switch can include the following:
1. Inconsistent heating: The electric furnace may start and stop erratically, or it may not heat at all.
2. High energy bills: The furnace may be running inefficiently, leading to high energy bills.
3. Short cycling: The furnace may turn on and off frequently, which can damage the system and shorten the lifespan of the components.
4. Blower fan running continuously: The blower fan may run continuously, even when the thermostat is set to a lower temperature.
5. Furnace overheating: The furnace may overheat, causing damage to the system and posing a safety hazard.
6. Furnace shutting down: The furnace may shut down unexpectedly, causing a loss of heat and potentially posing a safety hazard.
If you are experiencing any of these symptoms, it is important to contact a professional HVAC technician to diagnose the problem and replace the faulty limit switch if necessary.
How To Replace An Electric Furnace Limit Switch?
An electric furnace limit switch is a safety device installed inside a furnace to prevent overheating. The limit switch is typically located on the blower fan or heating element and is designed to turn off the power to the furnace when the temperature inside the furnace reaches a preset limit.
If your electric furnace limit switch is faulty, you will need to replace it. Here’s how you can replace an electric furnace limit switch:
1. Turn off the power to the furnace at the circuit breaker or fuse box.
2. Remove the access panel that covers the limit switch.
3. Disconnect the wires from the old limit switch.
4. Remove the old limit switch.
5. Connect the wires to the new limit switch.
6. Replace the limit switch in the furnace.
7. Turn the power back on to the furnace at the circuit breaker or fuse box.
It’s important to use caution when replacing an electric furnace limit switch. Be sure to disconnect the power before removing the limit switch and to reconnect the wires correctly. It’s also a good idea to consult an electrician if you are not sure how to replace a limit switch.
What Are The Common Types Of Electric Furnace Limit Switches?
Limit switches are devices that stop the operation of a heating or cooling device when the system reaches a preset temperature. They are commonly used in electric furnaces to prevent overheating.
There are several types of electric furnace limit switches, including:
1. Bimetallic: These switches use two metals that expand at different rates as the temperature rises. When the metal in the switch expands enough, it triggers the switch, which shuts off the furnace.
2. Thermostatic: These switches use a wax-filled capsule that expands as the temperature rises. When the wax expands enough, it triggers the switch, which shuts off the furnace.
3. Thermal fuse: These switches use a metal wire that melts at a preset temperature. When the wire melts, it triggers the switch, which shuts off the furnace.
4. Pressure switch: These switches use a diaphragm that deforms as the air pressure increases. When the diaphragm deforms enough, it triggers the switch, which shuts off the furnace.
5. Mechanical: These switches use a metal lever that bends as the temperature rises. When the lever bends enough, it triggers the switch, which shuts off the furnace.
It is important to properly install and maintain a limit switch to prevent overheating and damage to your furnace.
How To Maintain An Electric Furnace Limit Switch?
Maintaining an electric furnace limit switch is crucial for ensuring safe operation and preventing damage to the furnace. Here are some tips on how to properly maintain an electric furnace limit switch:
1. Regularly inspect the limit switch: Check the limit switch for any signs of wear and tear, such as loose connections or damaged wires. Look for any build-up of dust or debris, and wipe it off with a clean cloth.
2. Check the furnace’s wiring: Make sure the furnace’s wiring is in good condition and securely connected to the limit switch. Check for any signs of fraying or overheating.
3. Check the furnace’s temperature: Regularly check the furnace’s temperature to ensure it is within the recommended range. If the temperature is too hot or too cold, adjust the limit switch accordingly.
4. Check the limit switch’s calibration: The limit switch may need to be calibrated from time to time to ensure accurate operation. Use a thermometer to measure the furnace’s temperature, and adjust the switch to match the desired temperature.
5. Replace the limit switch if necessary: If the limit switch is damaged or worn out, replace it. A faulty limit switch can cause the furnace to overheat, leading to potential fire hazards.
6. Consult a professional: If you are not comfortable performing maintenance on the limit switch yourself, consult a professional. A qualified technician can ensure the furnace is properly calibrated and limit switch is working correctly.
7. Keep a record of maintenance: Keep a record of all maintenance performed on the limit switch, including the date and who performed the work. This can help you identify any issues in the future.
By following these tips, you can ensure the electric furnace limit switch is properly maintained and working correctly, reducing the risk of damage to the furnace or potential fire hazards.
Key Points
In conclusion, testing the limit switch on an electric furnace is a crucial step in ensuring its safe and efficient operation. By following the simple instructions provided in this article, you can quickly and easily determine if your limit switch is functioning properly. Remember, if you have any doubts or questions about the process, it is always best to consult with a qualified professional.
