furnace won't turn on

Reasons Your Furnace Won’t Turn On or Ignite When Expected

As temperatures fall and you expect your furnace to kick on automatically, it can be extremely frustrating when it fails. There are several indicators that your furnace may require repairs. An inoperable furnace leaves you cold; we will explore why yours might not ignite properly as well as ways to remedy this situation in this comprehensive guide. From gas furnaces and thermostats to other forms of HVAC equipment – whatever it may be, we have you covered!

1- Thermostat Issues

Your thermostat plays an essential part in telling your furnace when to turn on and off, so if your furnace won’t ignite it could be related to its malfunction.

Thermostat Setting Errors

One common cause for furnaces not turning on automatically can be traced back to thermostat setting errors. First, ensure your thermostat is set in “heat” mode with desired temperatures that exceed current room temperatures; also, ensure batteries aren’t dead, as this could create communication issues and result in non-functionality of thermostats.

Faulty Thermostat

If your thermostat is unresponsive or malfunctioning, it won’t send the signal to your furnace to start. Consider replacing it if it’s outdated or damaged.

2- Issues with Electrical Connections

Furnaces rely on a complex network of electrical connections to function correctly. If there’s an issue with these connections, your furnace may not ignite.

Circuit Breaker Tripped

Check your circuit breaker carefully to make sure it hasn’t tripped. If it has, reset it and see if the furnace starts working again. A tripped breaker can disrupt power to your furnace.

Faulty Wiring

Inspect the wiring around your furnace for any signs of damage or loose connections. Damaged wiring can prevent the ignition sequence from occurring.

3- Gas Supply Problems

If you have a gas furnace, a lack of proper gas supply can be a significant reason for ignition failure.

Gas Valve Shut Off

Ensure that the gas valve leading to your furnace is open. If it’s closed, no gas will reach the furnace burners, and ignition won’t occur.

Gas Supply Issues

Sometimes, the gas supply itself can be interrupted due to issues with the gas line or the gas company. If you suspect a gas supply problem, contact a professional immediately.

4- Dirty or Clogged Components

Over time, furnace components can accumulate dirt and debris, leading to ignition problems.

Dirty Burners

Dirty or clogged burners can prevent proper ignition. Cleaning or replacing them may resolve the issue.

Clogged Air Filters

A blocked air filter restricts airflow, which can interfere with the furnace’s ability to ignite. Regularly replace or clean your air filter.

5- Igniter Issues

The igniter is responsible for starting the combustion process in your furnace. Problems with the igniter can prevent ignition.

Broken Igniter

A broken igniter won’t produce the necessary spark to ignite the gas. Replacing the igniter may be necessary.

6- Flame Sensor Problems

The flame sensor ensures safety by detecting the presence of a flame. If it malfunctions, your furnace may not ignite or stay lit.

Dirty Flame Sensor

A dirty or corroded flame sensor may not detect the flame properly. Cleaning it can often resolve the issue.

7- High-Limit Switch Activation

This switch is a safety feature that shuts down the furnace if it overheats. If this switch is activated, your furnace won’t turn on.

Restricted Airflow

A common reason for the high-limit switch to activate is restricted airflow. Check for obstructions in the vents as well as ducts, or contact our heating services in Derry, NH for immediate solutions to all your heating concerns..

8- Thermocouple Troubles

The thermocouple is another safety feature in gas furnaces. It ensures that there’s a pilot flame before allowing the main burners to ignite.

Faulty Thermocouple

If the thermocouple is malfunctioning, it may not allow the main burners to ignite. Replacing it could be the solution.

9- Dirty or Faulty Sensors

Modern furnaces come with various sensors that monitor different aspects of the system. If these sensors are dirty or malfunctioning, they can prevent ignition.

Flame Rod Sensor

The flame rod sensor can become dirty over time, affecting its ability to detect the flame. Cleaning it can often resolve the issue.

Pressure Switch

A malfunctioning pressure switch may prevent the furnace from igniting. Consult a professional to diagnose and replace it if necessary.

10- Ignition Control Board Issues

The ignition control board is like the brain of your furnace, controlling various functions. If it’s malfunctioning, your furnace may not ignite.

Electrical Problems

Issues with the control board’s electrical components can disrupt the ignition process. A professional technician may need to diagnose and repair this problem.

11- Blocked Exhaust Vent

For safety reasons, furnaces have exhaust vents to expel harmful gases. If the exhaust vent is blocked, your furnace may not ignite.

Vent Inspection

Check the exhaust vent for obstructions such as debris, nests, or ice. Clear any blockages to ensure proper ventilation.

12- Fuel Supply Issues

If your furnace runs on oil, problems with the oil supply can lead to ignition failure.

Empty Oil Tank

Ensure that your oil tank isn’t empty. A lack of oil will prevent your furnace from igniting.

Clogged Oil Filter

The role of clogged oil filters is to restrict the flow of oil to the furnace. Regularly replace or clean the filter as needed.

13- Age and Wear

Furnaces, like all mechanical systems, have a finite lifespan. As they age, they become more prone to issues that can affect ignition.

Regular Maintenance

To prolong the life of your heating system and prevent ignition issues from wear and tear, schedule regular maintenance with professional furnace technicians.

14- DIY Attempts Gone Wrong

Sometimes, well-intentioned DIY attempts to fix minor issues can lead to bigger problems, potentially requiring an upgrade to your heating system. If you recently attempted a repair and your furnace won’t turn on, consider undoing your changes or consulting a professional.

Conclusion: Keeping Your Furnace Functional

A furnace is not igniting when it should result from a wide range of issues, from thermostat problems to clogged components and gas supply issues. Troubleshooting these problems systematically can often lead to a solution. Remember, safety should be your top priority, and if you’re unsure about any aspect of furnace repair, it’s best to seek professional help. With the right attention and care, you can ensure that your furnace functions reliably and keeps your home warm when you need it most.Contact Daigle Plumbing & HVAC technicians in Derry, NH today! We possess the expertise and equipment to diagnose and resolve intricate heating issues both swiftly and efficiently.

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