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Serving the Greater New Braunfels, TX Area

Serving the Greater New Braunfels, TX Area


Your Old Furnace Might Be Dangerous


When’s the last time you thought about your furnace? It might have been a little while. You certainly haven’t needed to fire it up lately! But summer is actually the best time to give your furnace some serious consideration. How was it running last year? Has it been less efficient, less effective, or experiencing some concerning issues? If your furnace is getting old, there’s one very important thing to be aware of: the safety hazard that your heat exchanger could pose if it is cracked. What is a heat exchanger? Why would it crack? What makes that so dangerous? We’ll tell you all about it.

What a Heat Exchanger Does

In a gas furnace, there is combustion. This means that the fuel is ignited and burned, which produces an exhaust product. Like any other situation involving fuel combustion, in your car for example, that exhaust contains carbon monoxide, which is extremely dangerous to breathe. The heat exchanger performs two of the most important jobs in the furnace. The hot combustion gasses are contained within it as air passes around it. This simultaneously heats the air and prevents the carbon monoxide from escaping into the air you breathe.

Why Heat Exchangers Crack

A crack in the heat exchanger of a relatively new furnace would be shockingly rare. This is a problem that happens as a furnace ages. Because of the stresses placed on the metal of the heat exchanger, there can be a lot of wear and tear. The combustion gasses are corrosive, and the constant expansion and contraction from heating and then cooling down can make the metal more brittle and prone to cracking. If a crack does occur, it will likely be compressed together when the heat exchanger is cold, but when it heats up and expands, the crack can widen, allowing those combustion gasses to escape.

Risks of Carbon Monoxide Exposure

Breathing carbon monoxide can lead to many symptoms including headache, dizziness, confusion, weakness, nausea, and vomiting. Extended or concentrated exposure can be fatal. While gas furnaces are in general perfectly safe, it is absolutely critical to have a working carbon monoxide detector and to get regular maintenance to catch risky problems early, especially as the furnace gets older.

Signs of a Cracked Heat Exchanger

Call for help with your old furnace in San Marcos, TX right away if you notice exterior corrosion, a flame of any color other than blue, soot inside the furnace, a rotten-egg smell, moisture pooling below the furnace, or strange sounds such as banging, whistling, scratching, or popping. If you suspect that your furnace may have been exhibiting any of these signs during the last winter, get service this summer so you’ll have plenty of time to replace the heat exchanger or, if necessary, consider replacing the furnace. You don’t want to end up with a serious safety hazard in January, and no heat while you try to get a new furnace installed!

At Thayer Air Conditioning, your comfort is our #1 priority! Contact us today.

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