Whether it’s a leaky furnace or if you throw 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, understanding how your heating system works and a little bit about some common furnace problems is vital in deciding whether you can troubleshoot on your own or if you need professional support. 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 unsure about the problem or aren't equipped with the necessary skills and tools, it's best to call a professional HVAC company like Allstar Heating & Air Conditioning. We can accurately pinpoint the issue and complete 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. The Furnace Is Leaking

A furnace can leak water for many reasons. One possibility is a condensate leak, where the water created during the combustion process is not effectively 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 lead to water—as well as dangerous gases—coming out of the furnace.

It is necessary to manage water leaks quickly to prevent further damage to your furnace. Reaching out to a professional HVAC technician like the crew at Allstar Heating & Air Conditioning is recommended to diagnose and resolve the issue successfully.

2. My Furnace Blows 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 plugged air filter, or a malfunctioning heating element. It could also be your furnace is overheating and shutting off as a safety measure.

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 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 lead to heat loss and reduced efficiency. Another reason your furnace is falling short is because it’s too small for your home, so it can’t generate enough heat to adequately warm the space. A malfunctioning thermostat or ductwork problems can also cause uneven heating.

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

If the problem won’t go away, consider contacting an experienced HVAC company, such as Allstar Heating & Air Conditioning, who can look over your system, determine the root cause and provide solutions such as furnace replacement, repairing ductwork or changing your thermostat settings.

4. My Furnace Won't Work

If your furnace is not working, there are a few steps you can take to troubleshoot before phoning a pro. Check if the thermostat is set properly and the batteries are not dead. 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 lie with the ignition system or gas supply. In that case, it's best to consult a seasoned 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 lead to inefficiency, increased energy consumption and potential damage to your furnace.

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 clogged with debris you should exchange it for a clean one—and ensure it is pointing in the right direction. Second, 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 staff at Allstar Heating & Air Conditioning. Prompt professional attention will help restore the proper functioning of your furnace and avoid more complications and high energy bills.

6. My Furnace Hums All the Time

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

If the noise doesn't go away, it is a good idea to  get in touch with a professional HVAC technician.

7. My Furnace Makes Loud Noises

If your furnace is emitting a consistent loud noise, it's important to handle the issue promptly to prevent further damage or potential safety risks.  One common cause of this is a malfunctioning 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.

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

8. My Furnace Won't Start

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 good. Then, see if the circuit breaker or fuse controlling the furnace is sending power to the unit. If these basic checks don't take care of 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 do the job, phone a professional for furnace repair.

9. My Furnace Is on but Not Igniting

Like a a furnace not turning 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 the air filter and looking over your circuit breakers are a good place to start.

Other common causes of a furnace not igniting include a faulty igniter or nonfunctional flame sensor. Symptoms of these include the furnace continually making an attempt to ignite without success, no heat production or the furnace is making a burning or gas smell. Both of these issues can be easily solved by HVAC professionals like the team at Allstar Heating & Air Conditioning.