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Why Is My Furnace Leaking Water

By December 9, 2022No Comments
A high-efficiency furnace.

When it comes to leaks, homeowners never imagine it happening in their home. Whether it is a leaking roof or a leak in your plumbing, this could be a nightmare scenario. Leaking water from any appliance or part of your home comes with a variety of issues. Mold growth, mildew smells, and damaged infrastructure are just a few of the disaster that can occur from a leak in the home. Consequently, a leaking furnace isn’t any less stressful. However, depending on the type of furnace, determines why it is leaking. Why is my furnace leaking water? Typically, a clogged line or clogged part that keeps condensation from building up.

Let’s take a look below at some more details regarding the different types of furnaces and if they all produce condensation.

Are There Different Types Of Furnaces

There are two types of furnaces that could be present in your home. Let’s take a look below at what makes them different from each other.

  • High-efficiency furnace (condensing) – with an annual fuel utilization efficiency (AFUE) of 90 percent or higher, this furnace is installed more often. It uses a cooling exhaust to produce condensation. Additionally, it has a PVC plastic pipe as an exhaust pipe.
  • Standard-efficiency furnace (conventional) – with an annual fuel utilization efficiency (AFUE) of less than 90 percent, this furnace is not as often installed. No condensation is created. Additionally, it has a metal pipe as an exhaust pipe.

The easiest way to determine which furnace you have installed in your home is by looking at the exhaust pipe. PVC exhaust pipe means you have a condensation unit. A metal exhaust pipe means you have a conventional unit with no condensation.

Hire a professional to fix any furnace leaking water.

Where Is The Leak

Furnaces can be tricky to understand. As a homeowner, you think it has a purpose to heat your home. Never once would you consider that your furnace could have what appears to be a condensation leak. Typically, a condensing unit might appear to have a water leak, while a conventional unit or non-condensing unit will likely not leak water. Let’s take a look below at why each furnace might leak water.

High-Efficiency Condensing Furnace

  • Condensate pump – if this pump fails, water will leak from the furnace. The typical lifespan of a condensate pump is between 3 and 5 years.
  • Condensate drain line – cracks or loose connections allow water to leak out from the drain line. Additionally, the drain line could get clogged fairly easily. Water would back up into the furnace and cause a leak.
  • Inducer assembly – if cracked, water leaks out of the furnace. The condensation runs into the exhaust/flue pipe and flows toward the condensate drain hose. Then the condensation leaves the condensate drain hose and enters the inducer assembly. If there is a crack in the assembly the water will just leak out.
  • Condensate drain hose – any clogging of a drain hose will cause water to back up into the PVC exhaust pipe and cause water pools on your floor.
  • Condensate trap – condensate traps are known to get clogged by dirt and debris from the furnace. Keep this trap clean and clear so that water doesn’t back up into the furnace and leak out.

Standard-Efficiency Conventional Furnace

  • Clogged drain line – just like in a high-efficiency condensing furnace, any drain line that becomes clogged will prevent water from exiting the unit. As it gets backed up, it finds a way to leak out.
  • Damaged drain pan – if you notice water on the floor around your furnace, it is likely a damaged drain pan. The drain pan is there to contain the water and when damaged cannot work effectively.
  • Failed condensate pump – just like the other furnace type, if a pump that has the job of removing water gets clogged or breaks down, the water will leak.
  • Frozen coil – if your evaporator coils freeze up, the ac unit will leak water. Since the furnace and ac unit are close to each other, it might give the appearance that the furnace is leaking, when it is not.

Other Recommended Maintenance

Now that you have an understanding of why your furnace is leaking water, you can turn your attention to why the furnace isn’t turning on. Make sure to read up on this so that you can troubleshoot before calling in a professional. Consequently, you might surprise yourself and be able to solve the problem before a large repair bill shows up.

Next, determine if it is time to replace the furnace. When a furnace isn’t turning on, it could be a sign of more repairs. It might be cheaper to just do a furnace replacement. Read up on how long it takes to replace a furnace so that you can plan your schedule on the day of installation.

Lastly, another good area to understand about your furnace is when to relight it. In some cases, when the power goes out, the furnace pilot light will stay on. However, in other cases, if the power goes out you might have to relight the furnace. Be sure to prepare for the possibility of relighting your furnace.

Don't forget to replace your furnace filters to get maximum use out of your furnace.

When Do I Call A Professional

The moment that you notice a leaking furnace, you should reach out to a professional HVAC professional technician. Someone with experience working on furnaces is key to success. Not only will they be able to identify the type of furnace you own, but they will also have the best solution for furnace repair. Also, call on your local home inspection team. There might be more going on with your plumbing. They can inspect the full HVAC and plumbing system as well as refer a reputable HVAC technician to repair the furnace.


Maintaining your furnace is just as important as maintaining the rest of your HVAC system. There are filters involved that should be replaced every 90 days or less to keep your indoor air quality high. Depending on how often you run your furnace will determine your maintenance needs. Check to make sure that your furnace isn’t collecting too much dust, debris, or pet hair. Call on your local home inspection team to verify that the furnace is working properly. Reach out to Avalon Home Inspections will check your furnace during a home inspection in Atlanta, GA.

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