Why is my Furnace Leaking?

Is there really ever a time when a leak isn’t a bad thing? Most of the time it’s a real problem and often a leak is a total disaster. If your furnace is leaking, even just a little bit, you better figure out which of these options you’re looking at and quickly! You’ve got to get a leak under control fast.

High Efficiency Systems

If you’ve got a system with an efficiency rating of 90 or more, it produces exhaust. Look for a yellow tag with a number in it to see if you have this type of system. The vent pipe will be made of PVC instead of metal if you do.

The exhaust created in a high efficiency system is a cool liquid. Anywhere cold things meet warm air you will normally see some condensation, just like a cold glass of water on a warm day. Most high efficiency systems will have a drain or pipe to allow this condensation to make its way out of your home. Often this goes through the floor.If the drainage system develops a problem, you will see that condensation start to pool around the furnace. There could be a leak in the pipes or the drain could be clogged.


Some systems will employ a whole-home humidifier to keep the inside air at the proper levels for comfort and health. This is a great feature, particularly in dry zones. However, it’s also another source for leaks. Your humidifier is connected to your home’s plumbing as well as the furnace. A crack, leak or clog can make water back up or pool in or around your furnace.

Other Sources

The furnace rarely gets a designated room to itself. It typically has to share space with a few other items like the air conditioning system or some plumbing. It could be that your furnace leak isn’t even coming from your furnace. It could be from another source in the same area. That doesn’t mean it’s OK to leave it alone. Water isn’t good for your furnace!

No matter what is causing the leak, the treatment begins in the same way. Have a qualified R&R Refrigeration technician inspect the unit and diagnose the problem. Furnaces should be fixed by the pros!