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Proudly Serving The Columbia Area Since 1985

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Proudly Serving The Columbia Area Since 1985


Fulmer Heating & Cooling Blog

Have a Hissing Furnace? Here’s Why That’s Bad.


You know what your furnace usually sounds like while it is in operation. But the new noise that you’ve been picking up on isn’t something that sounds entirely wrong.

Hissing can be tricky. It isn’t quite the same as the whoosh of air you’d expect from a functioning furnace heater. But it isn’t exactly a concerning noise the way a boom or screech would be.

Don’t be fooled. Hissing can indicate the need for furnace repair in Columbia, SC to address a very serious problem: a cracked heat exchanger.

Here’s what you need to know.

Why hissing can be problematic

If you pick up on the distict sound of hissing coming from your furnace, don’t just brush it off. This can very well be a sign that you have a cracked heat exchanger. This means that the hissing is created by combustion gases being leaked out of your heat exchanger and into your home.

The consequences of a cracked heat exchanger

If you ever notice the signs of a cracked heat exchanger (hissing and the smell of gas), you need to reach out to a professional as soon as possible. This can be a problem for your comfort and, more importantnly your safety.

The thing about a cracked heat exchanger is that you’d never actually see the issue with the naked eye. But when you turn your system on and the metal of this component warms up, it expands and allows those cracks to open up and let gas out.

Less gas in the heat exchanger means reduced heating for your home. On a more serious note though, this can also put you and your loved ones at risk of carbon monoxide poisoning. This can be indicated by dizziness, fatigue, nausea, and headaches.

Be on the alert for the smell of gas and shut off your furnace if you pick up on it. You should also call emergency services and evacuate the house too until it is safe to return. This will ensure that everyone stays safe until a repair technician arrives.

Can hissing indicate other issues too?

Yes, hissing can also indicate other problems in your heater. For example, you may hear hissing when your ductwork develops a hole or a leak that is allowed heated air to escape into your crawlspaces or walls. It may also indicate the build-up of dirt in parts of the system.

We know these other problems may sound less serious but we always find it best to treat any odd noises from your heater as serious. After all, it is a serious issue to pay more money for less comfort!

Whether your furnace is hissing, making other strange noises, or producing less warm air, you can always rely on our team to help. We can diagnose and address the issue properly so you can get back to enjoying a properly warm home again.

When you need help with a hissing furnace, contact Fulmer Heating & Cooling. We are proud to have served residents in the area for more than 30 years.

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