The most obvious sign of a leaky furnace is often stepping into a pool of water nearby. Your furnace may be leaking water for a number of reasons, some of which you can fix on your own and others of which call for professional assistance.

Knowing what kind of equipment you have in your house can help you better determine why your furnace is leaking water. We’ll go through the two main types of furnaces and how to determine which you have.

Once the possibilities have been reduced, we’ll examine the potential reasons of a leaky furnace, highlighting do-it-yourself remedies and suggesting when it’s essential to see an HVAC expert.

How To Handle A Furnace Leak

Even if you decide to hire a furnace repair firm, knowing the cause of your furnace’s water leak gives you the authority to select the best remedy and ask questions to learn how the repair will be carried out.

Here are some recommendations on what to do if you find a furnace leak before calling a repair service:

  • Find out what kind of furnace is in your house.
  • If you have either a traditional furnace or a high-efficiency condensing furnace, think about the leak sources that are most likely to occur.
  • Check to see if there are any leaks occurring when the air conditioner is on.
  • To identify the leak’s location, inspect the equipment.
  • Take into account how simple it would be for you to do minor DIY tests.
  • If the leak continues, call a repairman.

Although it can’t match the skills of a qualified industry professional, this guide is intended to lead you through potential reasons and remedies. If you’re experiencing various problems with your furnace, including water seeping from furnace components, call a local professional to prevent more damage.

What Kind Of Furnace Do I Have?

There are many similarities between a normal furnace and a high-efficiency condensing furnace. However, there are three key distinctions that may be used to identify the furnace type in your house.


The primary identifier of the type of equipment you have is the material of the furnace exhaust pipe. The flue pipe, also known as the exhaust pipe, is in charge of venting the exhaust from your furnace outside of your house. You most likely have a high-efficiency furnace if the pipe is polyvinyl chloride (PVC), which has the appearance of white plastic. A metal pipe indicates that your furnace is a conventional, standard efficiency model.


Finding the Annual Fuel Utilization Efficiency (AFUE) rating is another method for identifying the type of furnace. The device should have a yellow EnergyGuide label with the rating written on it. Standard efficiency furnaces typically have an efficiency rating of 80%, which means they use 80% of the energy produced to heat your house.

The chimney, air leaks, and other openings account for the remaining 20% of energy loss. A furnace is considered high efficiency if its AFUE rating is 90% or above. You should be able to choose the kind of furnace using your AFUE rating.


High-efficiency furnaces are standard in most contemporary homes. You probably enjoy the advantages of a high-efficiency model if you just moved into a new house or a property where the heating and cooling systems were changed. Conventional standard efficiency furnaces are common in older, extremely outdated homes.

Water Is Seeping From A High Efficiency Condensing Furnace.

Now that you have successfully established that you are dealing with a high-efficiency machine, let’s talk about the most typical causes of water leaks from furnaces.

When the two heat exchangers in the furnace absorb enough heat to transform the gas normally discharged from your appliance through the exhaust pipe into liquid, condensation is produced. The condensate drain typically transports the water outside of your residence.

Water will have no choice but to seep from the furnace if the condensate drain or pipe is plugged. Pouring an equal quantity of hot water and white vinegar through the line may be all that is necessary to clear the line.

If necessary, use the mixture to flush the line many times. Small obstructions are usually cleared by using this condensate line cleaning technique. The furnace should be examined and cleaned at least once a year to prevent a clogged condensate drain or pipe.

A malfunction with your condensate pump might cause a furnace leak even though the condensate drain and line are clear. The condensation (water) is forced out of the appliance and into the pipe by the pump.

A condensate pump typically lasts 3 to 5 years. Your pump may not function at its best if it is older than that. The cost of the pump is roughly $50, and expert replacement can cost up to $200.

Conventional Furnace Is Leaking Water

A classic sign of either an exhaust pipe that isn’t fitting properly or an issue with the built-in humidifier is water seeping from a conventional furnace. Excess water from the humidifier is drained through the furnace drain pipe. Water will accumulate and seep from the humidifier into the furnace if the drain pipe is clogged. When the humidifier is the problematic component, it will look that water is seeping from furnace parts.

Check the water lines for the furnace’s humidifier for breaks or little leaks. Check the lines’ fit to the humidifier once again. Leaks are easily made by improperly fitting lines.

Examine the exhaust pipe if the humidifier appears to be functioning properly. Water that is supposed to be evacuated from the furnace will leak if the pipe is loose or not fitted properly.

As you inspect the pipe, take care. Avoid touching it. Typical furnace exhaust pipes may heat up to unsafe levels. Contact a furnace specialist to fix or replace the pipe to prevent any potential damage.

When The Ac Is On, The Furnace Leaks Water.

If the water pool around your furnace only seems to increase when the air conditioner is running, the issue is probably with your air conditioner rather than your furnace. When the air conditioner works, it dehumidifies the air as well as cooling your house.

The condensate drain pipe of the air conditioner is normally used to expel the moisture it has drawn from the air. Water will collect on the ground if that drain line is clogged, develops a leak, or if there is a leak in the drain pan.

The AC drain tube is frequently situated next to or even on top of the furnace. Therefore, it’s simple to wonder “why is my furnace leaking water?” when the AC drain line is the real culprit.

However, if your AC hasn’t been running recently, the drain line isn’t where your leak is coming from. Make a call to an HVAC expert for assistance in choosing the best course of action.

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