Furnace Leaking Water | General Heating and Air Conditioning

Why is my furnace leaking water?

Carrier Furnace

It’s winter. The last thing homeowners want when they see their furnace is to see a puddle of water leaking from it. When this happens, panic tends to settle in. However, this is not an end all case.

There are a few possible causes to this problem.

A Condensation Leak

There are several possible causes within this one issue. If you have a high-efficiency furnace, meaning it has an Annual Fuel Utilization Efficiency (AFUE) rating of 90% or higher, your furnace will produce condensation. The condensation is drained through a floor drain. However, if the tubing that is responsible for this is clogged or broken, you can get a leak. Additionally, the floor drain itself could be clogged.

If you have a standard-efficiency furnace (you can tell this by looking at the exhaust pipe; standard-efficiency furnaces have a metal exhaust pipe), there should be no condensation. If there is, that could be your issue right there.

Issue with the Secondary Heat Exchanger

If a condensation leak isn’t the issue, another possible cause is an issue with the secondary heat exchanger. You want to hope this is not the issue, as this type of problem might be an expensive fix or might require a replacement furnace.

The Internal Drain is Clogged

Another possibility would be that the internal drain system is plugged. This happens if you are AC unit is still running and it shares this drain with the furnace. This can cause a clogged drain.

Your Furnace Humidifier Could Be Leaking

Your humidifier could be leaking inside your furnace, causing your issue. This is something that would typically be caught in the early stages if you get routine maintenance done. However, if you haven’t had a tune-up for your furnace, this might be your issue. You want to figure out the issue, as if your humidifier is leaking, it can do a lot of internal damage to the unit.

The bottom line is that leaks can cause problems for you, such as damaging floors and walls or leading to mold growth. The easiest and sure way to find a solution is to have a HVAC professional diagnose the issue and offer solutions to the problem.


The professionals at General Heating and Air Conditioning are ready and available to help you with keeping your home comfort system running smoothly. Contact us online or call us at (608) 271-3900.

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