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

Regardless of the cause, understanding how your heating system works and a little bit about some frequent 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 don't have the necessary skills and tools, it's best to call an experienced HVAC company like Marios Air Conditioning. We can accurately diagnose 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. Your Furnace Leaks Water

A furnace can leak water for several reasons. One possibility is a condensate leak, where the water created during the combustion process is not properly draining away. This might be due to a clogged 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 important to address water leaks immediately to prevent more damage to your furnace. Contacting a professional HVAC technician like the crew at Marios Air Conditioning is recommended to diagnose and resolve the issue properly.

2. My Furnace Makes Cold Air/Lack of Heat

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

If your furnace does not blow hot air, it's better to contact a skilled HVAC tech 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 result in heat loss and reduced efficiency. Another reason your furnace is falling short is because it’s not big enough for your home, so it can’t make enough heat to adequately warm the space. A defective thermostat or ductwork problems can also cause inconsistent heating.

To address this, first check your home’s insulation level and make sure it’s enough to insulate your home. Also, look at the thermostat to make sure it’s set right and the batteries are working.

If the problem lingers, consider contacting an experienced HVAC company, such as Marios Air Conditioning, who can inspect your system, determine the root cause and provide solutions such as furnace replacement, repairing ductwork or adjusting your thermostat settings.

4. My Furnace Isn't Running at All

If your furnace is not working, there are a couple of steps you can take to troubleshoot before phoning a professional. Check if the thermostat is set right 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 furnace.

If there is power but your furnace won't blow hot air, the problem may be with the ignition system or gas supply. In that case, it's a good idea to contact an experienced HVAC technician for diagnosis and repair.

5. My Furnace Turns On and Off

If your furnace is short cycling, that 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, more energy use and potential damage to your unit.

If you believe your furnace is short cycling, the first step is to check your unit’s air filter. Filters should be changed on a regular basis to ensure air flow, so if your furnace air filter is clogged with debris you should exchange it for a clean one—and ensure it is pointing in the right direction. If that doesn’t do the trick, check 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 team at Marios Air Conditioning. Prompt professional attention will help restore the proper functioning of your furnace and reduce the chance of additional complications and high energy bills.

6. My Furnace Is Making a Humming Noise

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

If the noise continues, it is better that you  contact a professional HVAC technician.

7. My Furnace Is Making a Loud Noise

If your furnace is making a consistent loud noise, it's important to handle the issue promptly to prevent further damage or potential safety hazards.  One common cause of this is a malfunctioning 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 safer to contact 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 right temperature, is in heating mode and the batteries are working. Then, see if the circuit breaker or fuse that goes to the furnace is working right. If these basic checks don't take care of 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 get the job done, phone a heating specialist for furnace repair.

9. My Furnace Is Not Igniting

Like a a furnace that won't turn on at all, a furnace that isn’t igniting can be the result of a dirty air filter or a tripped circuit breaker. So, checking out the air filter and looking over your circuit breakers are a good place to start.

Other likely causes of a furnace not igniting could be a faulty igniter or nonfunctional flame sensor. Signs of these include the furnace continuously making an attempt 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 addressed by HVAC specialists like the team at Marios Air Conditioning.