Whether it’s a leaky furnace or if you flick the switch to start 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 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 assistance. By observing the furnace's behavior, listening for strange 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 lack the necessary skills and tools, it's best to call a professional HVAC company like Custom Air Systems Inc. We can accurately identify the issue and perform 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 frequent heating problems:

1. My Furnace Is Leaking 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 could be due to a plugged condensate drain line or a broken condensate pump. Another potential 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 necessary to manage water leaks promptly to prevent additional damage to your furnace. Reaching out to a professional HVAC technician like the crew at Custom Air Systems Inc is recommended to diagnose and resolve the issue properly.

2. My Furnace Is Blowing Cold Air/Not Blowing Hot Air

Some possible 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 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 give an accurate assessment and advise you on the correct 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 lacks insulation, which can cause heat loss and lower efficiency. Another reason your furnace is struggling is because it’s not big enough for your home, so it can’t make enough heat to adequately warm the space. A defective thermostat or ductwork problems can also produce inconsistent heating.

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

If the problem won’t go away, consider calling an experienced HVAC company, such as Custom Air Systems Inc, who can look over 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 a few steps you can take to troubleshoot before calling a heating specialist. Ensure the thermostat is set right and the batteries are not dead. If the furnace still doesn't start, check the circuit breaker or fuse box to ensure 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 reach out to a seasoned HVAC technician for diagnosis and repair.

5. My Furnace Is Short Cycling

If your furnace is short cycling, it means it is turning on and off multiple times at short intervals as opposed to running in regular cycles like it ought to. This can lead to inefficiency, higher energy bills and potential damage to your heating system.

If you suspect your furnace is short cycling, the first step is to look at your unit’s air filter. Filters should be exchanged 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 ensure it is pointing in the right direction. Second, 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 team at Custom Air Systems Inc. Quick professional attention will help restore the proper functioning of your furnace and prevent additional complications and high energy bills.

6. My Furnace Is Making a Humming Noise

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

If the noise doesn't go away, it is better that you  employ a professional HVAC technician.

7. My Furnace Is Making a Loud Noise

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

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

8. My Furnace Is Not Turning On

If your furnace won't turn on, make sure the thermostat is set to the desired temperature, is in heating mode and the batteries are working. Then, check if the circuit breaker or fuse controlling the furnace is sending power to the unit. If these basic checks don't address 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

Similar to 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, examining 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 nonfunctional flame sensor. Indications of these include the furnace repeatedly trying 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 simply fixed by HVAC professionals like the team at Custom Air Systems Inc.