Whether it’s a leaky furnace or if you flip 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 cause, knowing how your heating system works and a little bit about some common furnace problems is essential 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 uncertain about the problem or aren't equipped with the necessary skills and tools, it's best to call a reputable HVAC company like Miller Climate Control LLC. 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 common heating problems:

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 properly draining away. This may be due to a blocked condensate drain line or a broken 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—coming out of the furnace.

It is necessary to address water leaks promptly to prevent further damage to your furnace. Contacting a professional HVAC technician like the crew at Miller Climate Control LLC is recommended to diagnose and resolve the issue properly.

2. My Furnace Makes Cold Air/Lack of Heat

Some possible 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 also may be your furnace is overheating and shutting off as a safety precaution.

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 offer an accurate assessment and suggest the proper 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 reduced efficiency. Another reason your furnace is falling short is because it’s not big enough for your home, so it can’t produce enough heat to completely warm the space. A defective thermostat or ductwork problems can also result in uneven heating.

To correct 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 ensure it’s set right and the batteries aren’t dead.

If the problem continues, consider contacting an experienced HVAC company, such as Miller Climate Control LLC, 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 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 correctly and the batteries are not dead. If the furnace still doesn't turn on, check the circuit breaker or fuse box to ensure power is reaching the unit.

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 best to consult a knowledgeable 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 frequently at short intervals instead of running in regular cycles like it should. This can cause inefficiency, higher energy bills and potential damage to your unit.

If you think your furnace is short cycling, the first step is to pull out your unit’s air filter. Filters should be switched out when they are dirty to ensure air flow, so if your furnace air filter is dirty you should exchange it for a clean one—and make sure it is pointing in the right direction. Second, look at 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 staff at Miller Climate Control LLC. Prompt professional attention will help restore the proper functioning of your furnace and avoid more 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 problems with the electrical hardware 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 best to  contact a professional HVAC technician.

7. My Furnace Is Making a Loud Noise

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

Because of the complexity of furnace systems and potential risks involved, it's better to get in touch 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 right temperature, is in heating mode and the batteries are functioning. Then, check if the circuit breaker or fuse that controls the furnace is working right. 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 do the job, phone 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 the result of a clogged air filter or a tripped circuit breaker. So, inspecting the air filter and taking a peek at your circuit breakers are a good place to start.

Other potential causes of a furnace not igniting could be a faulty igniter or malfunctioning flame sensor. Signs of these include the furnace continuously trying 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 very easily repaired by HVAC specialists like the team at Miller Climate Control LLC.