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 strike your home at any moment.

Regardless of the issue, learning how your heating system works and a little bit about some frequent furnace problems is essential in deciding whether you can troubleshoot on your own or if you need professional support. By watching 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 uncertain about the problem or aren't equipped with the necessary skills and tools, it's best to call a professional HVAC company like Herman Allen Plumbing, Heating & Cooling. 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 common heating dilemmas:

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 completely draining away. This may be due to a clogged condensate drain line or a malfunctioning condensate pump. Another potential 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 imperative to manage water leaks quickly to prevent further damage to your furnace. Consulting with a professional HVAC technician like the crew at Herman Allen Plumbing, Heating & Cooling is recommended to diagnose and resolve the issue effectively.

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

Some possible 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 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 won’t blow hot air, it's best to contact a trained HVAC technician to diagnose and fix the problem. They can provide an accurate assessment and suggest the appropriate 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 doesn’t have enough insulation, which can cause heat loss and reduced 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 broken thermostat or ductwork problems can also produce uneven heating.

To deal with this, first check your home’s insulation level and make sure it’s enough to keep warm air in and cold air out of your home. Also, look at the thermostat to see if it’s set right and the batteries aren’t dead.

If the problem continues, consider contacting an experienced HVAC company, such as Herman Allen Plumbing, Heating & Cooling, who can inspect your system, determine the root cause and provide solutions such as furnace replacement, repairing ductwork or changing 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 contacting a professional. Make sure the thermostat is set correctly and the batteries are not dead. If the furnace still doesn't power on, check the circuit breaker or fuse box to verify power is reaching the system.

If there is power but no heat, the problem may be with the ignition system or gas supply. In that case, it's better to contact an experienced HVAC professional for diagnosis and repair.

5. My Furnace Turns On and Off

If your furnace is short cycling, it means it is turning on and off often at short intervals instead of running in regular cycles like it should. This can cause inefficiency, increased energy consumption and potential damage to your furnace.

If you suspect your furnace is short cycling, the first step is to look at your unit’s air filter. Filters should be exchanged on a regular basis 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, go to your thermostat and make sure  it’s set right and the batteries are good.

If those two things don’t work, it’s best to call experts like the crew at Herman Allen Plumbing, Heating & Cooling. Immediate 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

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 notice your furnace making a humming noise, it is important to take action.

If the noise persists, it is a good idea to  contact a professional HVAC technician.

7. My Furnace Is Noisy

If your furnace is producing a persistent loud noise, it's important to address the issue quickly to prevent further damage or potential safety risks.  One common cause of this is a failing 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.

Given the complexity of furnace systems and potential risks involved, it's safer to contact 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 desired temperature, is in heating mode and the batteries are working. Then, verify that the circuit breaker or fuse that controls the furnace is sending power to the unit. If these basic checks don't fix the problem, you can inspect 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 get the job done, call a heating specialist for furnace repair.

9. My Furnace Won't Ignite

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

Other common causes of a furnace not igniting are a faulty igniter or faulty flame sensor. Symptoms of these include the furnace continually 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 easily solved by HVAC pros like the team at Herman Allen Plumbing, Heating & Cooling.