Whether it’s a leaky furnace or if you flick the switch to start your heating system when it gets chilly and it won’t start, common furnace problems can impact your home at any moment.

Regardless of the cause, 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 services. 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 unsure about the problem or don't have the necessary skills and tools, it's best to call an experienced HVAC company like Allstar Heating & Air Conditioning. We can accurately diagnose the issue and execute the required repairs or maintenance, so we can get your furnace ready to go ASAP.

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

1. The Furnace Is Leaking

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

It is necessary to address water leaks promptly to prevent more damage to your furnace. Reaching out to a professional HVAC technician like the crew at Allstar Heating & Air Conditioning is recommended to diagnose and resolve the issue properly.

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

Some potential 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 blocked air filter, or a malfunctioning heating element. It could also be your furnace is overheating and shutting off as a safety mechanism.

If your furnace won’t blow hot air, it's a good idea to contact a skilled HVAC tech to diagnose and fix the problem. They can give an accurate assessment and suggest the correct solution.

3. My Furnace Struggles to Keep Up

A frequent reason your furnace isn’t keeping up on a cold day is that your home is lacking insulation, which can result in heat loss and decreased efficiency. Another reason your furnace is struggling is because it’s too small for your home, so it can’t generate enough heat to completely warm the space. A malfunctioning thermostat or ductwork problems can also cause insufficient heating.

To address this, first assess your home’s insulation level and make sure it’s enough to keep warm air in and cold air out of your home. Also, examine the thermostat to ensure it’s set right and the batteries aren’t dead.

If the problem lingers, consider calling an experienced HVAC company, such as Allstar Heating & Air Conditioning, who can inspect your system, determine the root cause and provide solutions such as furnace replacement, repairing ductwork or changing 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 professional. Ensure the thermostat is set correctly and the batteries are fresh. If the furnace still doesn't start, check the circuit breaker or fuse box to ensure power is reaching the system.

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

5. My Furnace Turns On and Off

If your furnace is short cycling, this means it is turning on and off often at short intervals instead of running in regular cycles like it ought to. This can result in inefficiency, increased energy consumption and potential damage to your furnace.

If you believe your furnace is short cycling, the first step is to pull out your unit’s air filter. Filters should be exchanged on a regular basis to ensure air flow, so if your furnace air filter is dirty you should exchange it for a clean one—and ensure it is pointing in the right direction. Second, look at your thermostat and verify  it’s set right and the batteries are good.

If those two things don’t work, it’s best to call experts like the crew at Allstar Heating & Air Conditioning. Immediate professional attention will help restore the proper functioning of your furnace and reduce the chance of more complications and high energy bills.

6. My Furnace Won't Stop Humming

If your furnace is making a humming noise, it often is a sign of an issue with the electrical parts or the blower motor. Therefore, if you notice your furnace making a humming noise, it is crucial to take action.

If the noise continues, it is a good idea to  employ a professional HVAC technician.

7. My Furnace Is Noisy

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

Given 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 Can't Turn On

If your furnace won't turn on, make sure the thermostat is set to the desired temperature, is in heating mode and the batteries are working. Then, see if the circuit breaker or fuse controlling the furnace is working right. If these basic checks don't resolve 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 do the job, phone an expert for furnace repair.

9. My Furnace Is Not Igniting

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

Other likely causes of a furnace not igniting are a faulty igniter or malfunctioning flame sensor. Symptoms of these include the furnace continuously trying to ignite without success, no heat production or the furnace is making a burning or gas smell. Both of these issues can be simply solved by HVAC professionals like the team at Allstar Heating & Air Conditioning.