Condensate pump leaking?

If you notice furnace condensation or a puddle of water on the floor by your furnace when the heat is on, you likely have a high-efficiency condensing furnace. Causes of water on the floor can include problems with the condensate line, condensate pump (if you have one), humidifier, or filter. If your furnace is leaking turn off the system, clean up the water, and check the air filter. If the problem persists, contact an HVAC professional to inspect the furnace and/or the evaporator coil, drain pan, condensate line, and condensate pump.

Is it hard to fix a condenser leak?

If you notice furnace condensation or a puddle of water on the floor by your furnace when the heat is on, you likely have a high-efficiency condensing furnace. Causes of water on the floor can include problems with the condensate line, condensate pump (if you have one), humidifier, or filter. If your furnace is leaking turn off the system, clean up the water, and check the air filter. If the problem persists, contact an HVAC professional to inspect the furnace and/or the evaporator coil, drain pan, condensate line, and condensate pump.

How to fix condensation leak in furnace?

If you notice furnace condensation or a puddle of water on the floor by your furnace when the heat is on, you likely have a high-efficiency condensing furnace. Causes of water on the floor can include problems with the condensate line, condensate pump (if you have one), humidifier, or filter. If your furnace is leaking turn off the system, clean up the water, and check the air filter. If the problem persists, contact an HVAC professional to inspect the furnace and/or the evaporator coil, drain pan, condensate line, and condensate pump.

Furnace condensate pump leaking?

If you notice furnace condensation or a puddle of water on the floor by your furnace when the heat is on, you likely have a high-efficiency condensing furnace. Causes of water on the floor can include problems with the condensate line, condensate pump (if you have one), humidifier, or filter. If your furnace is leaking turn off the system, clean up the water, and check the air filter. If the problem persists, contact an HVAC professional to inspect the furnace and/or the evaporator coil, drain pan, condensate line, and condensate pump.

My furnace is leaking water?

If you notice furnace condensation or a puddle of water on the floor by your furnace when the heat is on, you likely have a high-efficiency condensing furnace. Causes of water on the floor can include problems with the condensate line, condensate pump (if you have one), humidifier, or filter. If your furnace is leaking turn off the system, clean up the water, and check the air filter. If the problem persists, contact an HVAC professional to inspect the furnace and/or the evaporator coil, drain pan, condensate line, and condensate pump.

Water leak from furnace?

If you notice furnace condensation or a puddle of water on the floor by your furnace when the heat is on, you likely have a high-efficiency condensing furnace. Causes of water on the floor can include problems with the condensate line, condensate pump (if you have one), humidifier, or filter. If your furnace is leaking turn off the system, clean up the water, and check the air filter. If the problem persists, contact an HVAC professional to inspect the furnace and/or the evaporator coil, drain pan, condensate line, and condensate pump.

Why is my furnace leaking water when heat is on?

If you notice furnace condensation or a puddle of water on the floor by your furnace when the heat is on, you likely have a high-efficiency condensing furnace. Causes of water on the floor can include problems with the condensate line, condensate pump (if you have one), humidifier, or filter. If your furnace is leaking turn off the system, clean up the water, and check the air filter. If the problem persists, contact an HVAC professional to inspect the furnace and/or the evaporator coil, drain pan, condensate line, and condensate pump.

Water leaking from furnace?

If you notice furnace condensation or a puddle of water on the floor by your furnace when the heat is on, you likely have a high-efficiency condensing furnace. Causes of water on the floor can include problems with the condensate line, condensate pump (if you have one), humidifier, or filter. If your furnace is leaking turn off the system, clean up the water, and check the air filter. If the problem persists, contact an HVAC professional to inspect the furnace and/or the evaporator coil, drain pan, condensate line, and condensate pump.

Furnace leaking water when ac is on?

If you notice furnace condensation or a puddle of water on the floor by your furnace when the heat is on, you likely have a high-efficiency condensing furnace. Causes of water on the floor can include problems with the condensate line, condensate pump (if you have one), humidifier, or filter. If your furnace is leaking turn off the system, clean up the water, and check the air filter. If the problem persists, contact an HVAC professional to inspect the furnace and/or the evaporator coil, drain pan, condensate line, and condensate pump.

HVAC Troubleshooting

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Why is My Furnace Leaking Water?

If you notice water on the floor near your furnace, don’t panic. If your furnace is leaking water, it’s a sign of a problem, but not necessarily a major or costly one. It depends on the root cause of the puddle.

If you have a water heater, washing machine, or wash tub in the same utility room or basement area, you may not have a leaking furnace at all. Make sure one of those units is not the source of the water. If the water is only under or next to your furnace, keep reading to pinpoint the cause.

Understanding the causes of furnace water leaks

A water leak from your furnace can have multiple causes, depending on the time of year. It can also depend on the type of furnace you have.

Why is my furnace leaking water when the heat is on?

If you notice furnace condensation or a puddle of water on the floor by your furnace when the heat is on, you likely have a high-efficiency condensing furnace. Causes of water on the floor can include problems with the condensate line, condensate pump (if you have one), humidifier, or filter.

A high-efficiency furnace (with an AFUE of 90% or higher) has a secondary heat exchanger. When the combustion exhaust gases leave the primary heat exchanger, instead of exhausting to the outside, they enter the secondary heat exchanger. In the secondary heat exchanger, additional heat is released from the flue gas and water vapor begins to form.

This change of state from water as a vapor to a liquid releases latent heat in the secondary heat exchanger, bringing the furnace to an even higher level of efficiency. The water drains out through a condensate drain line. When a high-efficiency furnace is leaking water, it can mean that the condensate drain line is clogged.

A standard efficiency furnace only has one heat exchanger, and will not produce the same condensation. If you’re not sure if you have a conventional furnace or a condensing furnace, check the exhaust pipe. If it’s metal, it’s a standard furnace. If it’s PVC and paired with an intake PVC pipe, you have a condensing furnace.

Whole-house humidifier

If you have a whole-house humidifier connected to your furnace and your home’s water lines, it may also be the culprit of water on the floor. A clogged humidifier pad, clogged or cracked drain line, or loose connections could be to blame.

Why is my furnace leaking water when the AC is on?

If you think your furnace is leaking water when the AC is on, you need to know that it’s not your furnace that is leaking, but another part of your HVAC system is to blame. If you have a split system with an indoor furnace and an outdoor AC unit, you also have an indoor evaporator coil that pairs with the furnace.

During normal operation, the evaporator coil produces condensation, which drains into a drain pan and then a floor drain under the unit. The drain pan can become clogged and overflow, causing a puddle of water near the furnace.

A dirty evaporator coil can literally freeze over. A professional should deal with a frozen evaporator coil. Turn off your air conditioner to prevent damage to your HVAC system. As the coil thaws, you will want to mop up the resulting water as soon as possible.

What to do if your furnace is leaking water

If you see water pooling near your furnace, take action.

Turn off the system

Whether it’s your condensing furnace leaking or you have a frozen evaporator coil, turning off the system at the thermostat or breaker box will prevent further problems.

Clean up the water

Promptly mop up the water with towels or a sponge. You may need to use a wet-dry vac. Once you have removed the excess water, you may want to use a fan to dry the area thoroughly. The longer you have standing water, the higher the risk of mold growth,

Check the air filter

A dirty air filter can be to blame for a frozen evaporator coil. It can also cause problems with your furnace. A clean filter can help improve your indoor air quality (IAQ).

Call for HVAC repair

Call HVAC professionals to inspect the furnace and/or evaporator coil, drain pan, condensate line, and condensate pump, and remove any clogs/resolve problems.

Schedule HVAC Repair

Preventing water leaking from the furnace

The best way to prevent your furnace from leaking water is to schedule professional furnace maintenance. The inner workings of your gas furnace, the venting system, and other parts of your forced air system require professional maintenance to keep the furnace running at peak efficiency.

Schedule a furnace tuneup each fall and an AC tuneup each spring. Consider signing up for an HVAC maintenance plan with your preferred HVAC company. They’ll contact you when it’s time for a maintenance call.

Consider opting into Trane Diagnostics

Opt into Trane Diagnostics for peace of mind. Through the Trane Home App, you can give your dealer remote monitoring capabilities. Your Trane smart thermostat sends data in real-time to your dealer, alerting them to any issues, sometimes before you even realize there’s a problem.

They can run furnace troubleshooting tests to pinpoint the problem. In some cases, they may be able to solve the problem remotely. In this situation, you would grant them one-time dealer remote access (DRA).

If they need to schedule an on-site service call, the technician will arrive with the knowledge gained from remote access. This enables shorter service calls and ensures the technician has the proper replacement parts.

Anne Fonda, Content Writer at Trane Technologies

A Content Writer with Trane Technologies, Anne Fonda researches topics and writes for Trane® and associated residential HVAC brands. She works in collaboration with Trane Technologies subject matter experts, offering easy-to-understand, informative content on complex topics. Her goal is to help consumers make informed decisions on the products and services they need.

She has written for HVAC and other service provider websites for over 16 years. Before transitioning to web content writing, Anne had a 14-year stint as an award-winning journalist. She graduated cum laude from the University of Missouri-Columbia School of Journalism. When she’s not working, Anne enjoys playing word games, reading, gardening, spending time with family, and visiting gardens and museums.

Expert review by John Kim, Senior Product Manager, Furnaces