What Can Cause a Furnace to Stop Working

A furnace that suddenly stops working can create an uncomfortable – and sometimes unsafe – situation, especially during colder months. From minor issues like clogged filters to major mechanical failures, there are many reasons why it may quit.

One popular brand that many homeowners turn to is Rheem, known for its reliable heating solutions. But how are Rheem furnaces rated? They’re known for their reliability, efficiency, and advanced features. In this guide, we’ll dive into common reasons it might stop working and offer insight into troubleshooting options.

What is the most common problem of a furnace?

Like any mechanical device, furnaces can experience issues that cause them to stop working. Understanding the potential causes can help in diagnosing problems and determining the best course of action:

1. Thermostat malfunctions

The thermostat acts as the brain of the heating system, regulating temperature and signaling the furnace to turn on or off. If the thermostat is malfunctioning, it may not send the proper signals, resulting in a furnace that won’t ignite or operate efficiently. Common issues include dead batteries, miscalibration, or faulty wiring. Regularly checking the thermostat settings and replacing batteries can prevent this problem.

2. Dirty air filters

Air filters play a vital role in ensuring that a furnace runs smoothly. When filters become clogged with dust and debris, airflow is restricted, leading to overheating and potential shutdowns. Dirty filters can also contribute to a decrease in indoor air quality. It’s essential to check and replace air filters every one to three months, especially during peak heating seasons.

3. Ignition problems

Furnaces typically utilize ignition systems such as pilot lights or electronic ignition to start the heating process. If the pilot light goes out or the electronic ignition fails, the furnace will not ignite. Ignition problems can result from dirt buildup, a faulty thermocouple, or a malfunctioning ignitor. Regular maintenance and cleaning can help prevent ignition issues.

4. Fuel supply issues

For gas furnaces, a disruption in the fuel supply can cause the furnace to stop working. This may be due to closed valves, gas line leaks, or an empty propane tank. In oil furnaces, running out of oil can halt operation. Checking fuel levels and ensuring that all valves are open can help address fuel supply problems.

5. Blower motor problems

The blower motor is responsible for circulating heated air throughout the home. If the motor is malfunctioning, the furnace may still produce heat, but it won’t be effectively distributed. Common symptoms include strange noises or the blower running continuously without turning off. Regular inspection and maintenance of the blower motor can help ensure its proper function.

6. Limit switch malfunctions

The limit switch is a safety device that prevents the furnace from overheating. If it fails, the furnace may shut down unexpectedly. This can happen due to dirt buildup, mechanical wear, or electrical faults. If the limit switch is malfunctioning, it may need to be replaced by a qualified technician.

7. Flame sensor issues

The flame sensor detects whether a flame is present in the combustion chamber. If it’s dirty or malfunctioning, it can falsely signal that the flame has gone out, causing the furnace to shut down for safety reasons. Regular cleaning of the flame sensor can prevent this issue.

8. Ductwork problems

Leaky or blocked ductwork can significantly impact a furnace’s efficiency. If ducts are damaged or improperly sealed, heated air may escape before reaching its intended destination. This not only affects heating performance but can also lead to increased energy bills. Inspecting and sealing ductwork can enhance overall system efficiency.

9. Electrical issues

Many furnaces rely on electrical components to function correctly. Problems with electrical connections, blown fuses, or tripped circuit breakers can disrupt furnace operation. It’s important to check the electrical system and ensure all connections are secure and functioning properly.

10. Aging equipment

Finally, older furnaces may experience issues simply due to age. Wear and tear can lead to decreased efficiency, increased frequency of breakdowns, and ultimately, complete failure. Regular maintenance can extend the life of a furnace, but at some point, replacement may be the most cost-effective option.