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 affect your home at any moment.

Regardless of the issue, knowing how your heating system works and a little bit about some common furnace problems is crucial in deciding whether you can troubleshoot on your own or if you need professional assistance. By observing 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 a professional HVAC company like Three Rivers Heating & Cooling. We can accurately pinpoint 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 common 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 effectively draining away. This might be due to a blocked condensate drain line or a failing condensate pump. Another potential 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 manage water leaks promptly to prevent further damage to your furnace. Consulting with a professional HVAC technician like the crew at Three Rivers Heating & Cooling 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 are a malfunctioning thermostat, a problem with the pilot light or ignition system, a clogged air filter, or a malfunctioning heating element. It is also possible your furnace is overheating and shutting off as a safety measure.

If your furnace won’t blow hot air, it's better to contact a trained HVAC tech to diagnose and fix the problem. They can provide an accurate assessment and recommend the proper solution.

3. My Furnace Can't Keep Up

A common reason your furnace isn’t keeping up on a cold day is that your home is lacking insulation, which can cause heat loss and decreased 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 completely warm the space. A malfunctioning thermostat or ductwork problems can also cause inconsistent heating.

To deal with this, first assess your home’s insulation level and make sure it’s enough to insulate your home. Also, look at the thermostat to ensure it’s set right and the batteries aren’t dead.

If the problem lingers, consider calling an experienced HVAC company, such as Three Rivers Heating & Cooling, 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 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 pro. Ensure the thermostat is set correctly 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 be with the ignition system or gas supply. In that case, it's a good idea to consult an experienced HVAC professional for diagnosis and repair.

5. My Furnace Is Short Cycling

If your furnace is short cycling, it means it is turning on and off frequently at short intervals as opposed to running in regular cycles like it should. This can result in inefficiency, increased energy consumption and potential damage to your furnace.

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 regularly 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. 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 smart to call experts like the staff at Three Rivers Heating & Cooling. Immediate professional attention will help restore the proper functioning of your furnace and avoid further complications and high energy bills.

6. My Furnace Hums All the Time

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

If the noise doesn't go away, it is a good idea to  contact 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 deal with the issue promptly to prevent further damage or potential safety hazards.  One common reason is a failing blower motor or fan, which can create a grinding or screeching sound. Another common cause is a loose or worn-out belt that may emit a squealing or rattling noise.

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

8. My Furnace Can't Turn On

If your furnace refuses to turn on, make sure the thermostat is set to the preferred temperature, is in heating mode and the batteries are good. Then, see if the circuit breaker or fuse that goes to the furnace is working right. If these basic checks don't fix the problem, you can inspect 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 work, contact 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 caused by a dirty air filter or a tripped circuit breaker. So, examining the air filter and assessing your circuit breakers are a good place to start.

Other likely causes of a furnace not igniting include a faulty igniter or nonfunctional flame sensor. Symptoms of these include the furnace continuously 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 fixed by HVAC professionals like the team at Three Rivers Heating & Cooling.