How to Reset Limit Switch on Furnace Safely

How to Reset Limit Switch on Furnace?

To reset the limit switch on a furnace, first, check if the pilot light is off.

Then, lower the thermostat to the lowest degree and light the furnace pilot light.

After that, set the thermostat to the desired temperature.

For furnaces older than 30 years, the reset process may vary and it is recommended to consult an HVAC professional if resetting the furnace does not resolve the issue.

Key Points:

  • Check if the pilot light is off
  • Lower the thermostat to the lowest degree and light the furnace pilot light
  • Set the thermostat to the desired temperature
  • Consult an HVAC professional for furnaces older than 30 years
  • Reset process may vary for older furnaces
  • Resetting the furnace may not resolve the issue, prompting the need for professional assistance


Did You Know?

1. The limit switch on a furnace is a safety device that shuts off the burner if the temperature inside the furnace becomes too high. It helps prevent overheating, which can lead to damage or even fires.

2. To reset the limit switch on a furnace, locate the switch usually near the burner assembly. On some furnaces, the switch is red or has a red reset button. However, not all limit switches are designed to be reset manually.

3. Some limit switches have an automatic reset feature, meaning they will reset themselves once the temperature returns to a safe level. This can save you the trouble of having to manually reset it.

4. If the furnace continues to trip the limit switch repeatedly, it may indicate a more serious issue, such as a clogged air filter, blocked vents, or a malfunctioning blower motor. In such cases, it’s advisable to call a professional technician to diagnose and fix the problem.

5. Regular maintenance, including cleaning or replacing the air filter, keeping the vents clear, and ensuring proper airflow, can help prevent the limit switch from tripping and prolong the lifespan of your furnace.

Resetting A Furnace: A Quick And Easy Fix For Most Modern Units

Resetting a furnace is a simple process that can resolve many common issues and get your heating system back up and running. Most furnaces less than 30 years old can be reset simply by turning the power off and back on. This power cycle can often reset the limit switch, which is a safety feature that can sometimes trip and prevent the furnace from operating properly.

When you encounter problems with your furnace such as uneven heating, unheated air, no air coming out of the vents, noise, or a musty smell, resetting the furnace is usually the first step to troubleshoot these issues. However, it’s important to note that if the furnace doesn’t have any air coming out and the pilot light is out, trying to reset the furnace may not resolve the problem, and you may need to consult a professional to investigate further.

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Resetting An Older Furnace: A Different Approach

To reset older furnaces, follow these steps:

  • Check if the pilot light is off and if it is, relight it.
  • Lower the thermostat to the lowest degree to prevent the furnace from producing heat during the reset process.
  • Light the furnace pilot light, following the specific manufacturer instructions in your furnace’s manual.
  • Once the pilot light is lit, proceed to the final step.
  • Set the thermostat to the desired temperature and make sure the furnace is functioning correctly.
  • If the reset process is successful, the furnace should start producing heat and distribute it evenly throughout your home.
  • If the issue persists or other problems arise, it is advisable to contact a professional HVAC technician for further assistance.

Remember to consult your furnace’s manual for specific instructions on relighting the pilot light and always prioritize safety precautions.

Step 1: Checking The Pilot Light

Before attempting to reset your furnace, it is essential to check if the pilot light is off. If the pilot light is not lit, it means that the furnace is not receiving the necessary fuel to produce heat. This can be due to a variety of reasons, such as a gas supply issue or a problem with the ignition system.

To relight the pilot light, follow the specific instructions provided in your furnace’s manual. Typically, this involves turning the gas valve to the pilot position, holding down the reset button, and using a match or a lighter to ignite the pilot flame. Once the flame is lit, continue holding down the reset button for a few moments to ensure the pilot remains lit. Release the reset button and switch the gas valve back to the on position.

Step 2: Lowering The Thermostat For Resetting

To effectively reset the furnace, it is crucial to lower the thermostat to the lowest possible temperature setting. This ensures that the furnace is not attempting to produce heat while you are in the process of resetting it. Lowering the thermostat will prevent any potential interference with the reset process and allows for a clean restart of the system.

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Once the thermostat is set to the lowest degree, proceed to the next step in resetting your furnace.

Step 3: Relighting The Furnace Pilot Light

Relighting the furnace pilot light is an essential step in the reset process, especially for older furnaces. Consult your furnace’s manual for specific instructions on how to relight the pilot light. The process may vary depending on the make and model of your furnace.

Typically, it involves:

  • Locating the pilot light assembly.
  • Turning the gas valve to the pilot position.
  • Using a match or a lighter to ignite the pilot flame.
  • Holding down the reset button while the pilot is lit, ensuring that the flame remains steady and consistent.
  • Once the flame is stable, release the reset button and switch the gas valve back to the on position.

Step 4: Setting The Thermostat And Ensuring Proper Functioning

After relighting the pilot light, set the thermostat to the desired temperature. This allows the furnace to resume its normal operation and begin producing heat. It is important to monitor the furnace closely after resetting and observe its performance. If the reset process has been successful, the furnace should distribute heat evenly throughout your home.

However, if the furnace continues to exhibit issues such as insufficient heat, constant blower operation, or unusual noises, it may indicate a problem that requires professional attention. In such cases, it is recommended to contact a licensed HVAC technician who can diagnose and resolve any underlying issues with your furnace.

It is vital to prioritize the maintenance of your furnace to ensure efficient heating, ensure your family’s safety, preserve indoor air quality, and save money on energy bills. Annual furnace inspections and regular filter replacements are strongly recommended to maintain clean air and optimal performance. By investing in proper furnace maintenance, you can extend the lifespan of your heating system and avoid costly repairs in the future.

Remember, if resetting your furnace does not solve any problems or if you require further assistance with your furnace, do not hesitate to contact a reputable HVAC professional. They have the expertise and knowledge to diagnose and repair any furnace issues you may encounter.

For professional help, you can reach XYZ HVAC at 844-216-9300.

Ensure your home stays warm and comfortable by keeping your furnace in optimal condition all year round.

  • *Set the thermostat to the desired temperature after relighting the pilot light.
  • Monitor the furnace closely after resetting for proper performance.
  • Contact a licensed HVAC technician if the furnace exhibits issues.
  • Prioritize furnace maintenance for efficient heating, safety, air quality, and energy savings.
  • Schedule annual inspections and regular filter replacements.
  • Contact XYZ HVAC at 844-216-9300 for professional assistance.*
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Frequently Asked Questions

How do I reset my furnace?

To reset your furnace, locate the switch that is either mounted on or near the furnace and switch it off. Wait for approximately 10 seconds before turning the switch or breaker back on. Once the power is restored, check the furnace to ensure it has been successfully reset and has power again. Remember to always exercise caution when dealing with electrical components and consult a professional if you are unsure or uncomfortable performing these steps yourself.

What is a manual reset temperature limit switch?

A manual reset temperature limit switch is a device that is used in various appliances, such as generators, coffee makers, and water heaters, to prevent excessive increase in temperature. Unlike automatic reset switches, which reset themselves once the temperature returns to normal, a manual reset limit switch needs to be manually reset by an operator after the temperature has been brought back to a safe level. This adds an extra layer of safety, ensuring that any potential overheating issues are addressed and resolved before the equipment or appliance can resume normal operation.

What is the limit switch on a furnace?

The limit switch on a furnace is a crucial safety device that controls the activation and deactivation of the furnace blower assembly. Its primary function is to regulate the distribution of warm air throughout the air ducts in a home. Additionally, the limit switch serves as a protective measure by shutting down the furnace if it detects that it is overheating, preventing potential hazards and damage.

Why reset a furnace?

Resetting a furnace is crucial to address specific situations and prevent potential hazards. One key reason to reset a furnace is to control excessive heat. By initiating a furnace reset, it halts the heating process and allows the system to cool down, averting any risk of a circuit breaker malfunction or more severe consequences. Similarly, if the furnace runs out of fuel, activating the reset button becomes imperative to restore functionality and ensure the uninterrupted operation of the heating system. The reset acts as a vital safety measure, enabling the furnace to start afresh once the fuel is replenished, guaranteeing a continuous and reliable heat supply.

References: 1, 2, 3, 4

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