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

Regardless of the issue, understanding how your heating system works and a little bit about some frequent furnace problems is vital in deciding whether you can troubleshoot on your own or if you need professional services. By noting 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 don't have the necessary skills and tools, it's best to call a reputable HVAC company like Classic Air. We can accurately diagnose the issue and execute the required repairs or maintenance, so we can get your furnace working again ASAP.

Here's more about what causes a furnace to leak water and eight other frequent heating dilemmas:

1. Your Furnace Leaks Water

A furnace can leak water for a number of reasons. One possibility is a condensate leak, where the water produced during the combustion process is not completely draining away. This might be due to a clogged condensate drain line or a broken 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 correct water leaks immediately to prevent more damage to your furnace. Consulting with a professional HVAC technician like the crew at Classic Air is recommended to diagnose and resolve the issue effectively.

2. My Furnace Makes Cold Air/Lack of Heat

Some likely causes for a furnace blowing cold air or not blowing hot air include 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 does not blow hot air, it's better to contact a professional HVAC specialist to diagnose and fix the problem. They can offer an accurate assessment and suggest the proper solution.

3. My Furnace Can't Keep Up

A widespread reason your furnace isn’t keeping up on a cold day is that your home lacks insulation, which can lead to heat loss and decreased efficiency. Another reason your furnace is having difficulties is because it’s too small for your home, so it can’t make enough heat to adequately warm the space. A malfunctioning thermostat or ductwork problems can also cause uneven heating.

To deal with 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, check the thermostat to make sure it’s set right and the batteries still function.

If the problem lingers, consider contacting an experienced HVAC company, such as Classic Air, who can assess your system, determine the root cause and provide solutions such as furnace replacement, repairing ductwork or adjusting 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 calling a professional. Check if the thermostat is set right and the batteries are fresh. If the furnace still doesn't start, check the circuit breaker or fuse box to verify power is reaching the system.

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

5. My Furnace Short Cycles

If your furnace is short cycling, it 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 result in inefficiency, increased energy consumption 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 on a regular basis to ensure air flow, so if your furnace air filter is dirty you should exchange it for a clean one—and make sure 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 Classic Air. Prompt professional attention will help restore the proper functioning of your furnace and avoid further 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 an issue with the electrical parts or the blower motor. Therefore, if you detect your furnace making a humming noise, it is crucial to take action.

If the noise persists, it is better that you  contact a professional HVAC technician.

7. My Furnace Makes Loud Noises

If your furnace is producing a constant loud noise, it's important to address the issue right away to prevent further damage or potential safety concerns.  One common cause of this is a malfunctioning blower motor or fan, which can generate a grinding or screeching sound. Another possible 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 better 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 preferred temperature, is in heating mode and the batteries are working. Then, see if the circuit breaker or fuse that controls the furnace is sending power to the unit. If these basic checks don't resolve 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 do the job, contact a heating specialist for furnace repair.

9. My Furnace Won't Ignite

Similar to a furnace that won't turn on at all, a furnace that isn’t igniting can be caused by a clogged air filter or a tripped circuit breaker. So, examining 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 nonfunctional flame sensor. Signs 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 repaired by HVAC specialists like the team at Classic Air.