3 Signs That May Mean You Need Furnace Repairs

While gas furnaces are one of the most effective heating options, they can also experience a wide variety of issues that will prevent them from working properly. If your furnace isn’t working properly, it can put a lot of additional strain on the furnace itself and your HVAC blower and can potentially cause them to wear out much sooner. This is why it is always important that you monitor your furnace so that you can spot when it isn’t working as it should and needs to be repaired. A furnace that won’t turn on is an obvious sign that it needs repairs, but here are a few other signs that you should also watch for.

1. Heating System Runs Almost Constantly

The fact that Texas has fairly warm winters means that your furnace usually shouldn’t need to run all that much. It may run twice an hour for around 15 minutes each time on much colder days, but it should never run almost constantly. If it does seem to run all the time, you can be certain that there is some issue limiting how much heat it produces. This happens most frequently because the furnace filter is clogged and limiting how much air is being circulated through the system. Another possibility is that your ductwork is damaged and allowing lots of hot air to escape into the unconditioned parts of the home, like the attic and/or crawl space.

Dust and debris coating the furnace burners can also drastically reduce how much heat the unit produces. If the burners are overly dirty then the gas flowing through them won’t fully combust. If the gas doesn’t burn completely, much less heat will be produced. Incomplete combustion also means that the flames coming from the burners will typically be weaker and orange or yellow in color instead of the strong, steady, blue flame you get when the gas combusts fully.

Unfortunately, most of the issues that can cause your furnace to run much more aren’t things that you can easily diagnose on your own. All you can really do is try replacing the furnace filter to see if this fixes the problem. If it doesn’t, then you will need to have your heating system inspected to find the specific cause and repair it.

2. Furnace Turns Off Almost Immediately After Starting

A furnace that only ever runs for a short time before shutting off can be a sign of several different issues. If your furnace only ever runs for less than 10 minutes at a time, it usually indicates that either the unit is too large for your home or that your thermostat is malfunctioning and signaling it to turn off too soon.

There are also situations where your furnace may only run for a short time and then not start again. This issue almost always indicates that the furnace or blower overheated, which triggers the high-temperature limit switch and automatically shuts down the system. If the limit switch does ever trigger, then your heating system won’t turn on again until the switch detects that everything has sufficiently cooled.

The most common reason a furnace will overheat is due to a dirty air filter, but it can also happen as a result of electrical issues, clogged vents or air leaks in your ductwork. If your air filter isn’t clogged and your furnace constantly overheats, you will want to have it inspected as soon as possible as all of the excess heat can easily damage the unit’s wiring and other components.

A furnace that lights and then immediately shuts off within a few seconds is caused by some issue with the unit’s flame sensor. The flame sensor is an electrical probe that detects if the burners are lit so that gas won’t continue to flow if the unit doesn’t light for any reason. The flame sensor can wear out with age and need to be replaced. However, the more common reason it will stop working properly is that it is coated in grime and dust, which will insulate the probe and prevent it from detecting the heat from the burner flames. In either case, the solution is to have a furnace technician test the flame sensor and either clean or replace it.

3. Heating System Runs Louder Than Normal or Makes Unusual Noises

If you notice that your heating system is suddenly much louder than normal, it is usually related to some issue with the blower and not the furnace itself. A blower that runs much louder normally indicates that it is working much harder to circulate air through the HVAC system, which can happen for a variety of reasons. It could be that the air filter is dirty or your return air vents are clogged or obstructed, both of which will restrict how much air the blower can draw in and force it to work harder. Another possibility is that the bearings that drive the blower motor are starting to wear out or that the motor itself is having issues.

Unusual noises, like banging, rattling, squealing or grinding, could be caused by a problem with either the furnace, the blower or potentially even your ductwork. A rattling noise could indicate that one of your ducts is sagging or loose or that the blower isn’t fully secured in its housing. Another even-more serious possibility is that your furnace’s heat exchanger has a major crack that is causing it to rattle whenever the unit runs. This is one issue that you will want to have a furnace technician check for immediately as a cracked heat exchanger will often lead to carbon monoxide leaking out.

There are also times when you may hear your furnace make a loud banging noise when it first lights that almost sounds like a small explosion. This issue occurs when the ports on the furnace burners are dirty and start to clog up. If the ports are clogged, it often leads to all of the burners not lighting immediately once gas starts to flow to the furnace. If the burners don’t light immediately, gas can begin to fill the combustion chamber. Once the burners do finally light, the gas build-up can produce a small fireball or miniature explosion.

This is another fairly serious issue as that fireball could easily damage various furnace components. Luckily, the solution to this issue is quite easy as all you need to do is have a technician remove and clean all the burners. You can also prevent this problem by having your furnace maintained every year as this includes cleaning the burners and all the other components.

Carrollton’s Heating and Cooling Experts

At Dring Air Conditioning & Heating, our certified technicians have years of experience repairing all types of furnace issues. We work on all types and brands of furnaces, and our team can also assist with furnace maintenance and installation. We also install and service air conditioners, thermostats, ductwork and indoor air quality equipment, like air filtration systems, whole-home humidifiers and HVAC ventilators. Give us a call today if you’re having any issues with your furnace or need to schedule any other heating or cooling service.

Dennis Chaisson

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