Why Won’t My Gas Furnace Turn On?

Furnace Won't Turn On? Here's What To Do Burford Heating
Furnace Won't Turn On? Here's What To Do Burford Heating from burfordheating.ca


Having a gas furnace that won’t turn on can be a frustrating experience, especially during the cold winter months. There can be several reasons why your gas furnace is not starting, ranging from simple issues that you can fix yourself to more complex problems that require professional assistance. In this article, we will explore the most common causes of a gas furnace not turning on and provide some troubleshooting tips to help you get your furnace working again.

1. Thermostat Settings

The first thing you should check when your gas furnace won’t turn on is the thermostat. Make sure it is set to the desired temperature and set to the “heat” mode. Also, check if the thermostat has power and replace the batteries if necessary. Sometimes, a simple adjustment or battery replacement can solve the issue.

2. Gas Supply

Another common reason for a gas furnace not turning on is a problem with the gas supply. Check if the gas valve is open and the gas supply is not interrupted. If you suspect a gas leak, it is important to contact a professional immediately for assistance.

3. Pilot Light

If your gas furnace has a pilot light, make sure it is lit. If it has gone out, follow the manufacturer’s instructions to relight it. If the pilot light won’t stay lit or keeps going out, there may be an issue with the thermocouple, which is a safety device that shuts off the gas supply if the pilot light goes out. In such cases, it is best to consult a professional technician.

4. Ignition System

Modern gas furnaces often use an electronic ignition system instead of a pilot light. If your furnace has an electronic ignition system, check if it is working properly. Look for any signs of damage or wear and tear. If there are any issues with the ignition system, it may need to be repaired or replaced by a professional.

5. Air Filter

A clogged or dirty air filter can restrict airflow and cause the furnace to overheat, triggering a safety feature that shuts it off. Check the air filter and clean or replace it if necessary. It is recommended to clean or replace the air filter every one to three months to ensure proper airflow and efficient heating.

6. Circuit Breaker

If your gas furnace is not receiving power, check the circuit breaker or fuse box. Make sure the circuit breaker that controls the furnace is in the “on” position. If it has tripped or a fuse has blown, reset the breaker or replace the fuse. If the breaker keeps tripping or the fuse keeps blowing, there may be an electrical issue that requires professional attention.

7. Blower Motor

The blower motor is responsible for circulating warm air throughout your home. If the blower motor is not functioning properly, your gas furnace may not turn on. Listen for any unusual noises coming from the blower motor or check if it is running when the furnace should be operating. If you suspect a problem with the blower motor, it is best to consult a professional technician.

8. Blocked Vents or Ducts

Blocked vents or ducts can restrict airflow and cause your gas furnace to shut off. Check all vents and ducts to ensure they are not obstructed by furniture, rugs, or debris. Clear any obstructions and make sure the vents are open and unobstructed to allow proper airflow.

9. Safety Features

Gas furnaces are equipped with various safety features to protect against potential hazards. If any safety feature is triggered, such as a limit switch or flame sensor, the furnace may not turn on. In such cases, it is recommended to contact a professional technician to diagnose and fix the issue.

10. Professional Assistance

If you have tried the troubleshooting tips mentioned above and your gas furnace still won’t turn on, it is time to seek professional assistance. A qualified HVAC technician will have the knowledge and expertise to diagnose and repair the problem accurately.


A gas furnace not turning on can be a frustrating problem, but with some troubleshooting, you may be able to identify and fix the issue yourself. However, if you are unsure or uncomfortable with any of the troubleshooting steps, it is always best to consult a professional technician to avoid any further damage or safety hazards. Remember, regular maintenance and servicing of your gas furnace can help prevent many of these issues and ensure efficient and reliable heating during the cold months.