Whether it’s a leaky furnace or if you flip the switch to turn on your heating system when the weather gets cold and it won’t start, common furnace problems can affect 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 support. 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 an experienced HVAC company like Controlled Comfort HVAC. We can accurately diagnose the issue and execute the required repairs or maintenance, so we can get your furnace working again ASAP.

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

1. My Furnace Is Leaking Water

A furnace can leak water for many reasons. One possibility is a condensate leak, where the water produced during the combustion process is not properly 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 be responsible for water—as well as dangerous gases—escaping from the furnace.

It is necessary to correct water leaks immediately to prevent additional damage to your furnace. Reaching out to a professional HVAC technician like the crew at Controlled Comfort HVAC is recommended to diagnose and resolve the issue properly.

2. My Furnace Is Blowing Cold Air/Lack of Heat

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 clogged 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 specialist to diagnose and fix the problem. They can give an accurate assessment and advise you on 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 doesn’t have enough insulation, which can result in heat loss and reduced efficiency. Another reason your furnace is struggling is because it’s not powerful enough for your home, so it can’t generate enough heat to effectively warm the space. A malfunctioning 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, examine the thermostat to make sure it’s set right and the batteries aren’t dead.

If the problem won’t go away, consider contacting an experienced HVAC company, such as Controlled Comfort HVAC, who can inspect 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 some steps you can take to troubleshoot before calling 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 verify power is reaching the system.

If there is power but your furnace won't blow hot air, the problem may rest with the ignition system or gas supply. In that case, it's better to reach out to a knowledgeable HVAC professional for diagnosis and repair.

5. My Furnace Turns On and Off

If your furnace is short cycling, it means it is turning on and off frequently at short intervals instead of running in regular cycles like it ought to. This can lead to inefficiency, more energy use and potential damage to your unit.

If you suspect your furnace is short cycling, the first step is to pull out 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 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 smart to call experts like the staff at Controlled Comfort HVAC. 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 symptom of an issue with the electrical elements or the blower motor. Because of this, if you hear your furnace making a humming noise, it is critical to take action.

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

7. My Furnace Makes Loud Noises

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

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

8. My Furnace Can't Turn On

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

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

9. My Furnace Won't Ignite

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

Other likely causes of a furnace not igniting are 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 very easily repaired by HVAC specialists like the team at Controlled Comfort HVAC.