Why Is Water Leaking from My Furnace?

December 21, 2018

Your furnace doesn’t use water to operate, so it can be worrisome when you come home to see a puddle of water below it. If your furnace is leaking water, it can be a sign that something is either leaking, dripping, or not draining properly. However, sometimes it can be a very minor issue. Let’s take a look at the most common reasons your furnace is leaking water.

Furnace Condensation

Do you have a high efficiency furnace? If so, they commonly produce condensation. An easy way to tell if you have a high-efficiency furnace is to look at its vent pipe; if there is a PVC pipe attached, you have a high-efficiency furnace.

The condensation from a high-efficiency gas furnace is generally guided to a floor drain via a drain hose. Your leak could be a result of the condensation tubing, or the floor drain, becoming clogged. You can fix the problem with chemical tablets and a larger drain hose.

If you have a standard-efficiency furnace, one with a metal pipe attached, it should never leak condensation. If you see a leak, it could mean that the exhaust pipe is the wrong size for your unit.

Exhaust Pipe

The metal exhaust pipe connected to your furnace is designed to collect and take away the gases that are naturally produced. Those gases are meant to exit the exhaust pipe and enter the outdoors before they have time to cool down and condense into water. If the exhaust pipe is the wrong size, or if it doesn’t slope upwards enough, the gas doesn’t always make it outside in time. The gases will then cool down and condense into water while still in the exhaust pipe, causing a water leak. Call a professional to replace or redesign the exhaust pipe.

Condensate Pump

Some furnaces use a condensate pump to push condensation toward a drain. A condensate pump is a box connected to the PVC drain pipe and pumps water away from the unit. If the condensate pump isn’t working properly, or stops working altogether, you’ll see water dripping or overflowing from the device. Call a professional to replace the unit if you see water leaking from this area.

Secondary Heat Exchanger

The heat exchanger in a furnace separates the combustion process from your breathing air. Air is heated as it’s blown across the hot metal surface of the heat exchanger, then that heated air is distributed through your home. In other words, a heat exchanger is essential.

Heat exchangers will need replaced on occasion due to metal fatigue. Heated up metal expands, and when it cools off it contracts. Over time, expansion and contraction has the same effect on a heat exchanger that bending a thin piece of metal does—it breaks.

Visual observation of water, or even light, passing through the breach means that you have a crack or hole in the heat exchanger, which will need to be replaced by a professional as soon as possible.

Furnace Humidifier

If you have a humidifier installed on the outside of your furnace, it may be malfunctioning if you see a puddle of water. These devices prevent dry air by adding moisture to the warm air that is blown into your home. However, issues with the humidifier, such as a clogged drain or filter, can cause the unit to leak. Have a professional inspect the humidifier to see what is causing the leak and fix the issue.

Leaving your furnace to leak can potentially cause damage and added expense. Give us a call at (316) 462-2572 to diagnose and repair your furnace leak. We also offer 24/7 emergency service.