Whether it’s a leaky furnace or if you flick the switch to turn on 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, learning 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 watching 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 not sure about the problem or aren't equipped with the necessary skills and tools, it's best to call a professional HVAC company like Comfort Zone, LLC. We can accurately diagnose the issue and perform 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 frequent heating issues:

1. My Furnace Is Leaking Water

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

It is necessary to address water leaks immediately to prevent more damage to your furnace. Consulting with a professional HVAC technician like the crew at Comfort Zone, LLC is recommended to diagnose and resolve the issue properly.

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

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

If your furnace does not blow hot air, it's best to contact a professional 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 common reason your furnace isn’t keeping up on a cold day is that your home is lacking insulation, which can lead to heat loss and decreased efficiency. Another reason your furnace is having difficulties is because it’s not powerful enough for your home, so it can’t make enough heat to adequately warm the space. A defective thermostat or ductwork problems can also produce inconsistent heating.

To address this, first check your home’s insulation level and make sure it’s enough to keep warm air in and cold air out of your home. Also, look at the thermostat to see if it’s set right and the batteries are working.

If the problem continues, consider calling an experienced HVAC company, such as Comfort Zone, LLC, who can look over your system, determine the root cause and provide solutions such as furnace replacement, repairing ductwork or changing your thermostat settings.

4. My Furnace Is Not Working

If your furnace is not working, there are a couple of steps you can take to troubleshoot before phoning a pro. Check if 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 your furnace won't blow hot air, the problem may lie with the ignition system or gas supply. In that case, it's a good idea to reach out to an experienced HVAC technician for diagnosis and repair.

5. My Furnace Is Short Cycling

If your furnace is short cycling, that means it is turning on and off multiple times at short intervals as opposed to running in regular cycles like it should. This can cause inefficiency, increased energy consumption and potential damage to your heating system.

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

If those two things don’t work, it’s smart to call experts like the crew at Comfort Zone, LLC. Immediate professional attention will help restore the proper functioning of your furnace and avoid additional complications and high energy bills.

6. My Furnace Is Making a Humming Noise

Whenever your furnace is making a humming noise, it often is an indication of an issue with the electrical parts or the blower motor. For this reason, if you hear your furnace making a humming noise, it is critical to take action.

If the noise persists, it is a good idea to  contact a professional HVAC technician.

7. My Furnace Is Making a Loud Noise

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

Due to the complexity of furnace systems and potential risks involved, it's better to consult with a heating and cooling specialist.

8. My Furnace Is Not Turning On

If your furnace refuses to turn on, make sure the thermostat is set to the desired temperature, is in heating mode and the batteries are functioning. Then, verify that the circuit breaker or fuse controlling the furnace is working right. If these basic checks don't fix the problem, you can inspect the furnace's power switch or emergency shutoff switch to ensure they're in the "on" position and weren’t accidentally turned off.

If those steps don’t do the job, phone a professional for furnace repair.

9. My Furnace Is Not Igniting

Similar to a furnace that won't turn on at all, a furnace that isn’t igniting can be caused by a clogged air filter or a tripped circuit breaker. So, examining the air filter and assessing your circuit breakers are a good place to start.

Other potential causes of a furnace not igniting include a faulty igniter or faulty flame sensor. Symptoms of these include the furnace repeatedly making an attempt to ignite without success, an absence of heat production or the furnace is making a burning or gas smell. Both of these issues can be easily repaired by HVAC professionals like the team at Comfort Zone, LLC.