Whether it’s a leaky furnace or if you throw the switch to turn on your heating system when the weather gets cold and it won’t start, common furnace problems can strike your home at any moment.

Regardless of the problem, 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 services. By observing 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 Northglenn Heating & Air Conditioning. We can accurately identify 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 common heating problems:

1. My Furnace Is Leaking Water

A furnace can leak water for a number of 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 blocked condensate drain line or a malfunctioning 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 imperative to deal with water leaks immediately to prevent more damage to your furnace. Consulting with a professional HVAC technician like the crew at Northglenn Heating & Air Conditioning is recommended to diagnose and resolve the issue successfully.

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 blocked 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 does not blow hot air, it's best to contact a skilled HVAC specialist to diagnose and fix the problem. They can give an accurate assessment and suggest the proper solution.

3. My Furnace Is Not Keeping Up

A widespread 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 lower efficiency. Another reason your furnace is struggling is because it’s too small for your home, so it can’t generate enough heat to effectively warm the space. A broken thermostat or ductwork problems can also result in uneven heating.

To address this, first assess 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 see if it’s set right and the batteries aren’t dead.

If the problem won’t go away, consider consulting with an experienced HVAC company, such as Northglenn Heating & 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 Is Not Working

If your furnace is not working, there are some steps you can take to troubleshoot before phoning a professional. 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 ensure power is reaching the furnace.

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

5. My Furnace Short Cycles

If your furnace is short cycling, this means it is turning on and off frequently at short intervals rather than running in regular cycles like it should. This can lead to inefficiency, higher energy bills and potential damage to your heating system.

If you believe your furnace is short cycling, the first step is to look at your unit’s air filter. Filters should be changed 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. If that doesn’t do the trick, look at your thermostat and look to see if  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 Northglenn Heating & Air Conditioning. 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

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

If the noise persists, it is a good idea to  get in touch with a professional HVAC technician.

7. My Furnace Is Noisy

If your furnace is making a constant loud noise, it's important to handle the issue quickly to prevent further damage or potential safety concerns.  One common reason is a broken blower motor or fan, which can generate a grinding or screeching sound. Another possible cause is a loose or worn-out belt that may produce a squealing or rattling noise.

Due to the complexity of furnace systems and potential risks involved, it's safer to get a hold of 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 good. Then, see if the circuit breaker or fuse that goes to the furnace is functioning properly. If these basic checks don't resolve the problem, you can check 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 work, phone an expert for furnace repair.

9. My Furnace Is Not Igniting

Much like a furnace not turning on at all, a furnace that isn’t igniting can be caused by a dirty air filter or a tripped circuit breaker. So, checking out the air filter and assessing your circuit breakers are a good place to start.

Other common causes of a furnace not igniting could be a faulty igniter or malfunctioning flame sensor. Indications of these include the furnace continually 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 fixed by HVAC pros like the team at Northglenn Heating & Air Conditioning.