furnace leaking water

Finding water around your furnace can be a cause of concern and must be inspected immediately. Whether you find your furnace leaking water during the heating cycle or in other circumstances, you should take prompt action and attention to prevent damage and ensure your system continues to operate efficiently.

In this article, we’re explaining the top reasons why your furnace is leaking water and how to deal with those issues.

But first, what should you do immediately as you see the furnace leaking water?

Turn Off the Furnace

Turning off the furnace is the first line of defense against further water leakage. You can turn off the system by finding the main power switch or by adjusting the thermostat. Doing so will lessen the likelihood of additional electrical dangers and water damage.

Contain the Leak

Get rid of the water around the furnace by using a wet/dry vacuum, towels, or rags. If you don’t get rid of water right away, it can seep into your home and ruin your walls, floors, and even cause mold.

Inspect the High Efficiency Furnace Unit

Investigate the area around the pooled water and look for signs of a leak. Keep an eye out for obvious indicators like water spilling from the pipes or condensation on the furnace.

Check External Components

Check the condensate pump and drain pipes, among other external components, for any blatant indications of blockage or dysfunction. Verify the integrity and proper attachment of all pipes and hoses.

Call an HVAC Expert

Get in touch with a skilled HVAC expert from a reputable firm like Comfort Union after you’ve done everything you can to lessen the damage. A professional can examine the area thoroughly, determine the source of the leak, and fix it properly. A small problem can quickly become a big repair bill or system failure if not addressed by a professional.

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Why Choose Us?

For starters, we will show up on time with a fully stocked service van, eager to resolve your heating, cooling, plumbing or electrical problem.

Common Causes of Furnace Leaks - How to identify them and troubleshoot them?

It is critical to act swiftly in the event that you discover water surrounding your furnace in order to avoid harm to both your system and your property. To save both time and money, it’s helpful to know what causes furnace leaks and how to fix them.

Cause: The reason behind this is that condensation forms in high-efficiency furnaces because their exhaust pipe gases are chilly. These furnaces usually have an AFUE rating of 90% or greater. Condensate drain lines, pumps, or traps are commonly used to direct this water vapor away from the system.


  • Inspect the Condensate Drain Hose: Look for leaks or obstructions in the condensate drain line. Make sure all connections are tight, and use a solution of vinegar and hot water to unclog any pipes.

  • Examine the Condensate Pump: Check that the condensate pump is not overflowing and that it is operating properly. It may be necessary to replace the pump if it is malfunctioning.

  • Check the Condensate Trap: To prevent water from backing up and leaking out of the furnace, check the condensation trap and remove any debris that may be blocking it.

Cause: The condensate drain pipe might get clogged with dirt, debris, or mold, which causes water to back up and pour out around the furnace.


  • Clean the Clogged Drain Line: If there are any clogs in the floor drain pipe, use a wet/dry vacuum to remove them. Another option for light blockages and mold removal is to flush the line with a vinegar and water mixture.

Cause: The condensate pump keeps the water output of your high-efficiency condensing furnace to a minimum. You can experience a condensate pump leaking if something goes wrong with it.


  • Inspect the Pump: Look for any indications of trouble while inspecting the pump. Keep an ear out for strange noises or see if the water is draining correctly. Should the pump fail to function as intended, you must replace it.

Cause: The accumulation of condensation and subsequent backflow into the furnace unit can be caused by an inadequately sized or installed flue pipe, which in turn leads to inefficient exhaust gas expulsion.


  • Flue Pipe Inspection: Inspect the flue pipe to make sure it is the right size and that it is installed correctly in relation to your furnace. In order to keep water from recirculating, it should be slightly inclined away from the furnace.

Cause: If not maintained properly, a built-in humidifier might lead to water leaking, which increases the amount of moisture around the furnace.


  • Check the Humidifier: Look for water line leaks and make sure the humidifier is draining properly before you use it. Leaks can be easily avoided with regular cleaning and maintenance.

Cause: When the AC unit leaks, water can collect around the furnace, which can cause problems in systems where the two units share components.


  • Check the AC Drain Pan and Line: Verify that the drain line is unobstructed and that the drain pan is not cracked. As needed, fix or replace the pan.

Cause: Thermomechanical stress and heat can cause the heat exchanger to break with time, which in turn allows water to flow out.


  • Professional Inspection: Due to the complexity and potential safety issues with a cracked heat exchanger, it is recommended to have a trained HVAC specialist examine the system - whether it is your primary heat exchanger or secondary heat exchanger.

Cause: When the furnace is switched on, water can flow out of the thawed evaporator coil if it freezes.


  • Check Airflow and Refrigerant Levels: Make sure there's enough refrigerant and adequate airflow in your system. To avoid air filter restrictions or blockages that can cause freezing, change them periodically.

Cause: Excessive condensation or a lack of regular emptying of the furnace's drain pan could cause the pan to overflow, which would be a problem if the furnace had one.


  • Regular Maintenance: Especially during times of heavy use, make sure to check the drain pan frequently and remove any debris that may have accumulated there.

Cause: Condensation within the furnace might become worse if the air filter is unclean or clogged, which restricts the passage of air and causes other problems.


  • Filter Replacement: To maintain adequate circulation and avoid condensation buildup, you should change the air filter in your furnace on a regular basis (at least every three months).

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Comfort Union: The solution to all your furnace repair needs

You can trust Comfort Union to fix your furnace quickly and expertly so that your home stays warm all winter long. From simple water leaks to more complicated system problems, every HVAC professional in our team can handle it all. And if you ever experience an emergency, we offer 24/7 emergency help.

We also provide thorough maintenance plans to keep your furnace running smoothly and trouble-free for as long as possible. Comfort Union’s dedication to its customers is evident in the individualized attention, transparent communication, and customized heating solutions it offers. In order to keep your house warm and cozy, you can rely on our dependable and effective furnace maintenance services.

Frequently Asked Questions about Furnace Leaking Issues

Is furnace leaking water dangerous?

Even while a leaking furnace does not necessarily pose an immediate threat to safety, it should be fixed as soon as possible in order to minimize unnecessary water damage and potential concerns such as the growth of mold or electrical shorts.

Is it normal for a furnace to drain water?

Yes, it is typical for high-efficiency furnaces to incorporate condensate drain systems in order to remove water that is created during the heating process during the heating process.

Can a dirty filter cause a furnace to leak water?

Yes, it is true that a dirty filter can hinder airflow, which can lead to the evaporator coil freezing and then thawing, which ultimately results in an excess of water that takes the form of a leak.

Why does my furnace leak water when my air conditioner is on?

In most cases, this occurs due to the fact that the furnace and air conditioner share an internal drain system. Problems with the air conditioner, such as a clogged condensate line, can cause water to accumulate and leak from the furnace.

Is water in your furnace dangerous?

Yes, it is possible for it to be hazardous because it might result in electrical failures, it could raise the chance of mold growth, and it could cause the components of your furnace to deteriorate.

Why is my furnace leaking water from the bottom in the winter?

The accumulation of condensation within high-efficiency furnaces or the thawing of frozen evaporator coils are two common causes of this phenomenon, both of which are more likely to occur when the temperature is low in the winter.

How do I stop my furnace from leaking water?

By doing routine maintenance, such as replacing the air filter, cleaning the condensate drain system, and performing routine inspections, it is possible to reduce the likelihood of leaks occurring.

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