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 impact your home at any moment.

Regardless of the cause, learning how your heating system works and a little bit about some typical furnace problems is essential in deciding whether you can troubleshoot on your own or if you need professional assistance. By monitoring the furnace's behavior, listening for unusual 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 don't have the necessary skills and tools, it's best to call a reputable HVAC company like Custom Air Systems Inc. We can accurately diagnose the issue and perform 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. My Furnace Is Leaking Water

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 could 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 be responsible for water—as well as dangerous gases—leaking out of the furnace.

It is necessary to correct water leaks quickly to prevent additional damage to your furnace. Contacting a professional HVAC technician like the crew at Custom Air Systems Inc is recommended to diagnose and resolve the issue effectively.

2. My Furnace Makes Cold Air/Lack of Heat

Some likely 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 mechanism.

If your furnace will not blow hot air, it's best to contact a skilled HVAC technician to diagnose and fix the problem. They can give an accurate assessment and suggest the appropriate solution.

3. My Furnace Struggles to Keep Up

A widespread 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 lower efficiency. Another reason your furnace is having difficulties is because it’s not big enough for your home, so it can’t generate enough heat to completely warm the space. A broken thermostat or ductwork problems can also result in insufficient heating.

To correct this, first assess your home’s insulation level and make sure it’s enough to protect your home. Also, look at the thermostat to ensure it’s set right and the batteries still function.

If the problem continues, consider consulting with an experienced HVAC company, such as Custom Air Systems Inc, 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 Is Not Working

If your furnace is not working, there are a few steps you can take to troubleshoot before calling a heating specialist. Ensure the thermostat is set right and the batteries are not dead. If the furnace still doesn't power on, check the circuit breaker or fuse box to make sure power is reaching the furnace.

If there is power but your furnace won't ignite, the problem may rest with the ignition system or gas supply. In that case, it's better to contact a knowledgeable 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 often at short intervals rather than running in regular cycles like it is designed to do. This can result in inefficiency, increased energy consumption and potential damage to your unit.

If you suspect 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 plugged with dirt you should exchange it for a clean one—and make sure it is pointing in the right direction. Next, go to your thermostat and verify  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 crew at Custom Air Systems Inc. Quick professional attention will help restore the proper functioning of your furnace and prevent additional complications and high energy bills.

6. My Furnace Is Making a Humming Noise

If your furnace is making a humming noise, it often is a symptom of problems with the electrical components or the blower motor. For this reason, if you detect 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 Makes Loud Noises

If your furnace is emitting a persistent loud noise, it's important to handle the issue right away to prevent further damage or potential safety hazards.  One common reason is a malfunctioning blower motor or fan, which can generate a grinding or screeching sound. Another common 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 safer to consult with a heating and cooling specialist.

8. My Furnace Is Not Turning On

If your furnace won't turn on, make sure the thermostat is set to the preferred temperature, is in heating mode and the batteries are working. Then, see if the circuit breaker or fuse controlling the furnace is sending power to the unit. If these basic checks don't address the problem, you can check 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 get the job done, contact an expert for furnace repair.

9. My Furnace Is on but Not Igniting

Much like a furnace that won't turn 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 common causes of a furnace not igniting include a faulty igniter or malfunctioning flame sensor. Symptoms of these include the furnace continually attempting 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 solved by HVAC professionals like the team at Custom Air Systems Inc.