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

Regardless of the cause, understanding how your heating system works and a little bit about some typical furnace problems is vital in deciding whether you can troubleshoot on your own or if you need professional services. 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 don't have the necessary skills and tools, it's best to call an experienced HVAC company like Northwest Services. We can accurately diagnose 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. Your Furnace Leaks Water

A furnace can leak water for several reasons. One possibility is a condensate leak, where the water released during the combustion process is not properly draining away. This might be due to a plugged condensate drain line or a failing condensate pump. Another possible cause of water leakage from a furnace is a cracked heat exchanger, which can result in water—as well as dangerous gases—leaking out of the furnace.

It is important to manage water leaks immediately to prevent more damage to your furnace. Consulting with a professional HVAC technician like the crew at Northwest Services is recommended to diagnose and resolve the issue properly.

2. My Furnace Makes 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 mechanism.

If your furnace will not blow hot air, it's best to contact a skilled HVAC tech to diagnose and fix the problem. They can provide 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 is lacking insulation, which can result in 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 produce enough heat to completely warm the space. A defective thermostat or ductwork problems can also cause inconsistent heating.

To address this, first look at 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 are working.

If the problem lingers, consider contacting an experienced HVAC company, such as Northwest Services, who can look over 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 few steps you can take to troubleshoot before calling a heating specialist. Make sure the thermostat is set properly and the batteries are good. If the furnace still doesn't turn on, check the circuit breaker or fuse box to verify power is reaching the furnace.

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 a good idea to contact an experienced 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 rather than running in regular cycles like it should. This can result in inefficiency, more energy use and potential damage to your furnace.

If you believe 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 plugged with dirt 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, check 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 crew at Northwest Services. Quick professional attention will help restore the proper functioning of your furnace and avoid additional complications and high energy bills.

6. My Furnace Hums All the Time

If your furnace is making a humming noise, it often is an indication of a malfunction with the electrical parts or the blower motor. Because of this, if you detect your furnace making a humming noise, it is critical to take action.

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

7. My Furnace Makes Loud Noises

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

Given the complexity of furnace systems and potential risks involved, it's best 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 good. Then, check if the circuit breaker or fuse that goes to the furnace is working right. If these basic checks don't take care of the problem, you can check 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 get the job done, contact an expert for furnace repair.

9. My Furnace Is Not Igniting

Like a 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, inspecting the air filter and assessing 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. Symptoms of these include the furnace continually attempting 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 easily addressed by HVAC pros like the team at Northwest Services.