What Are Common Furnace Repair Problems?

Many things can cause your furnace to malfunction. HVAC systems are intricate, and some homes may have outdated or damaged wiring in the system. A few issues with furnaces are a bit more common than others, though.

Some of the most common problems with furnaces are a furnace that won’t produce any heat, a furnace that is not turning on when it should, a furnace that keeps running through power cycles, or a furnace that is leaking water. Most of these problems are easily fixed.

In the paragraphs below, I’ll dive deeper into each of these problems that could potentially affect your furnace. I’ll explain why it happens and what you can do to fix it.

1. A Furnace That Won’t Produce Any Heat

Waking up in the middle of a winter night to find that your furnace has not been producing heat is a terrible thing to experience. However, this issue can potentially be solved very quickly.

The first thing you should do is check your thermostat. Check the temperature reading and make sure that it’s accurate. Additionally, check that it is still set to the heat setting. If your thermostat has a fan setting, you will want to turn this off.

If the fan setting is on, then the fan in the HVAC system will blow constantly but will only blow warm air when the furnace is on. The problem may not be that your furnace isn’t producing warm air; it may just be that the fan is blowing in cold air after the furnace shuts off.

Turning off the fan setting is easy enough to do on both analog thermostats and the newer smart thermostats. Turning off the fan will not only keep your home warmer but also save you money on your energy bill.

If the thermostat isn’t the culprit, you may be dealing with an issue with the pilot light. If your system uses one, it may malfunction. Both newer and older furnaces can experience problems with the pilot light or ignition system.

In older systems, the pilot light will simply go out. When this happens, there is nothing to ignite the fuel that is used to warm the air before it is piped into the home. In newer systems, there is no constant flame. The fuel is ignited automatically when the furnace is activated. The newer systems can have issues with the automatic ignition system, which will require professional service.

Unless you know what you’re doing and have extensive knowledge of your HVAC system and your furnace, you should not attempt to repair any ignition system yourself. This is highly dangerous and can result in gas leaks and explosions.

Read: Can You Install A Furnace Yourself?

Have a Question? Ask HVAC Technician

Click here to use the chatbox to speak with one of our technicians.
No in-home service calls. No appointments.

2. A Furnace That Keeps Turning Off and On

A furnace that is constantly running through power cycles can be worrisome but also very annoying.

This is usually a pretty innocuous problem that is easily fixed. It has to do with the temperature setting on your thermostat. The temperature may not be far off the current temperature of the room. 

This confuses the thermostat. When the temperature drops, it activates the furnace, but if the room temperature is not far below the desired temperature of the thermostat, the room heats up quickly, and the thermostat shuts off.

This could happen several times within a short period since the thermostat is trying to keep the room at the desired temperature but can’t find the correct balance.

You can solve this quickly by simply adjusting the temperature value up or down a few degrees, depending on what you would like the temperature to be. If this doesn’t solve the issue, you may have a clogged air filter.

A dirty air filter that’s clogged will limit the amount of air flowing through the system. This can cause the furnace to overheat, and in an effort to prevent a fire, the furnace will shut off.

This problem can be easily fixed by simply replacing the air filters in your home. You just need to figure out the filter size in each home area, then head to your local hardware store to purchase new ones.

Installing the new filters is a relatively simple process. The only tool you will need is a screwdriver:

  1. Use the screwdriver to remove the outer metal grate on the air filter. 
  2. Behind it, you will see the filter itself. 
  3. Remove the old filter by simply pulling it out and replacing it with the new one. 
  4. Then replace the grate and re-insert the screws.

Replacing the air filters in your home is something you should do periodically to keep your furnace running correctly and your house smelling fresh and clean.

Read: How Much Is A New Furnace For A 2000 Square-Foot Home?

3. A Furnace That Isn’t Turning On Automatically

If you find that your furnace isn’t turning on automatically when it should, then you can try a few simple things yourself to see if you can get it back up and running.

The first place you want to go is to your thermostat. Make sure that the thermostat is set to heat. If it is on any other setting, the furnace won’t turn on. This is true even if the thermostat displays a temperature where the heat should be triggered.

You may also want to ensure that you have fuel for your heating system. If you have electric heat, this isn’t something you need to worry about. However, if your furnace burns fuel, you must ensure that it has enough fuel to activate.

If you’ve checked the thermostat settings and the fuel level and neither of those is the problem, you can try resetting the furnace by flipping the furnace switch on your circuit breaker. This can work well for electric heat systems that can sometimes experience glitches.

It’s also important that if you plan to do any maintenance on your furnace yourself that you turn off the power to the furnace to keep yourself safe. This is especially true if your furnace burns gas and uses a pilot light. Leaving the power on could lead to an explosion while you’re working on the furnace.

Read: Why Furnace Ignitor Lights But No Flame? How To Troubleshoot?

4. A Furnace That Is Leaking Water

If you’ve looked at your furnace and found that there is water around the base of the furnace, you might be ready to panic. 

Many modern furnaces are made to be more efficient in the way they work. This means heating up and cooling down quickly between uses. Many modern furnaces have a cool exhaust system meant to assist the furnace in cooling off.

This creates condensation, most of which is captured by a pipe and drained. However, some water can escape, and if the drainage pipe becomes clogged, the water will have nowhere to go and end up on the floor.

All types of dirt and debris could potentially cause the drainage pipe to become clogged. If you haven’t checked the drain pipe or cleaned it out in a while you will want to do so even if the furnace is not yet leaking any water. This is an essential preventative maintenance measure.

You can check the drainage pipe for any clogs, but if the pipe is clear and free of clogs or blockages this type of issue is best dealt with by a professional HVAC technician. They can assess the problem quickly and repair it.

Read: Furnace Clicks But Doesn’t Turn On – Troubleshooting Guide