Whether it’s a leaky furnace or if you throw the switch to power up your heating system in the fall and it won’t start, common furnace problems can affect your home at any moment.

Regardless of the issue, understanding how your heating system works and a little bit about some common furnace problems is crucial in deciding whether you can troubleshoot on your own or if you need professional assistance. By monitoring the furnace's behavior, listening for peculiar noises and checking for signs of damage or blockage, you can narrow down the possible causes.

If you're uncertain about the problem or lack the necessary skills and tools, it's best to call a professional HVAC company like Indoor Comfort Systems HVAC. We can accurately identify the issue and execute the required repairs or maintenance, so we can get your furnace up and running ASAP.

Here's more about what causes a furnace to leak water and eight other prevalent heating problems:

1. The Furnace Is Leaking

A furnace can leak water for many reasons. One possibility is a condensate leak, where the water created during the combustion process is not completely draining away. This could be due to a clogged condensate drain line or a malfunctioning condensate pump. Another possible cause of water leakage from a furnace is a cracked heat exchanger, which can lead to water—as well as dangerous gases—leaking out of the furnace.

It is important to address water leaks immediately to prevent further damage to your furnace. Consulting with a professional HVAC technician like the crew at Indoor Comfort Systems HVAC is recommended to diagnose and resolve the issue properly.

2. My Furnace Is Blowing Cold Air/Not Blowing Hot Air

Some possible causes for a furnace blowing cold air or not blowing hot air are a malfunctioning thermostat, a problem with the pilot light or ignition system, a clogged air filter, or a malfunctioning heating element. It is also possible your furnace is overheating and shutting off as a safety mechanism.

If your furnace does not blow hot air, it's better to contact a trained HVAC technician to diagnose and fix the problem. They can give an accurate assessment and recommend the appropriate solution.

3. My Furnace Is Not Keeping Up

A widespread reason your furnace isn’t keeping up on a cold day is that your home lacks insulation, which can cause heat loss and reduced efficiency. Another reason your furnace is struggling is because it’s not big enough for your home, so it can’t generate enough heat to completely warm the space. A malfunctioning thermostat or ductwork problems can also cause inconsistent heating.

To address this, first assess your home’s insulation level and make sure it’s enough to protect your home. Also, check the thermostat to ensure it’s set right and the batteries aren’t dead.

If the problem continues, consider consulting with an experienced HVAC company, such as Indoor Comfort Systems HVAC, who can assess your system, determine the root cause and provide solutions such as furnace replacement, repairing ductwork or modifying your thermostat settings.

4. My Furnace Won't Work

If your furnace is not working, there are a few steps you can take to troubleshoot before phoning a pro. Ensure the thermostat is set correctly and the batteries are fresh. If the furnace still doesn't power on, check the circuit breaker or fuse box to ensure power is reaching the furnace.

If there is power but no heat, the problem may be with the ignition system or gas supply. In that case, it's best to contact a seasoned HVAC technician for diagnosis and repair.

5. My Furnace Short Cycles

If your furnace is short cycling, it means it is turning on and off often at short intervals instead of running in regular cycles like it is designed to do. This can cause inefficiency, higher energy bills and potential damage to your unit.

If you think your furnace is short cycling, the first step is to check your unit’s air filter. Filters should be exchanged regularly to ensure air flow, so if your furnace air filter is clogged with debris you should exchange it for a clean one—and be sure it is pointing in the right direction. Next, check your thermostat and look to see if  it’s set right and the batteries are good.

If those two things don’t work, it’s a good idea to call experts like the staff at Indoor Comfort Systems HVAC. Quick professional attention will help restore the proper functioning of your furnace and avoid more complications and high energy bills.

6. My Furnace Won't Stop Humming

When your furnace is making a humming noise, it often is a symptom of problems with the electrical components or the blower motor. Because of this, if you notice your furnace making a humming noise, it is important to take action.

If the noise persists, it is better that you  employ a professional HVAC technician.

7. My Furnace Is Noisy

If your furnace is making a constant loud noise, it's important to handle the issue promptly to prevent further damage or potential safety hazards.  One common problem that causes this is a broken blower motor or fan, which can create a grinding or screeching sound. Another possible cause is a loose or worn-out belt that may make a squealing or rattling noise.

Because of the complexity of furnace systems and potential risks involved, it's best to get a hold of a heating and cooling specialist.

8. My Furnace Won't Start

If your furnace will not turn on, make sure the thermostat is set to the desired temperature, is in heating mode and the batteries are good. Then, see if the circuit breaker or fuse that goes to the furnace is functioning properly. If these basic checks don't address the problem, you can examine the furnace's power switch or emergency shutoff switch to verify they're in the "on" position and weren’t accidentally turned off.

If those steps don’t work, phone an expert for furnace repair.

9. My Furnace Won't Ignite

Similar to a furnace that will not on at all, a furnace that isn’t igniting can be caused by a dirty air filter or a tripped circuit breaker. So, inspecting the air filter and taking a peek at your circuit breakers are a good place to start.

Other potential causes of a furnace not igniting are a faulty igniter or faulty flame sensor. Indications of these include the furnace continuously trying to ignite without success, a lack of heat production or the furnace is making a burning or gas smell. Both of these issues can be simply repaired by HVAC pros like the team at Indoor Comfort Systems HVAC.