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Why Is My Furnace Leaking Water?

As temperatures begin to drop and homeowners start to turn on their heating systems for the first time this season they might take a quick look at their furnace to make sure everything is in proper order. Is the heat on and warm? Check. Okay, time to move on.

Three weeks later you’re surprised to find a puddle of water collecting around your furnace, especially since you know your furnace doesn’t use water to operate. You’re left asking yourself, “Why is my furnace leaking water?”

This is a common question we hear from our neighbors, and there’s a few reasons why your furnace is leaking water. Below, we’ve outlined what might be causing your furnace to leak, but it’s best to let a professional HVAC contractor diagnose the warning signs your furnace is giving you—like leaking water.

Reasons Why Your Furnace Is Leaking Water

1. Condensation Leaks

Modern furnace models are more energy efficient than older units. As these newer heating systems pump cool exhaust away from your unit it may cause an increase in condensation collecting at the base of your furnace and is one reason why your furnace is “leaking” water. If you don’t have a high-efficiency furnace, you may have an incorrectly sized flue pipe, since standard efficiency furnaces do not produce condensation.

2. Clogged Internal Drain

Your furnace shares an internal draining system with your air conditioner. If this drain becomes clogged or plugged it could be redirecting water into the furnace and causing it to leak water.


3. Leaky Humidifier

Furnace humidifiers are connected to your home’s plumbing system and use tap water to add moisture to your air. If your humidifier clogs or cracks it will cause water to leak from your plumbing onto your furnace, giving the perception that your furnace is leaking water.

4. Leaky Pipes Near Your Furnace

Similar to a humidifier leaking water onto your furnace, leaky plumbing pipes may also be to blame for your furnace leaking water. Additionally, a clogged plumbing pipe could cause a backup in a floor drain, also making it appear that your furnace is leaking.

5. Heat Exchanger

One of the most expensive repairs if your furnace is leaking water, a malfunctioning secondary heat exchanger could be the cause of a leaky furnace. If you can’t figure out why your furnace is leaking water, call your HVAC contractor to diagnose the issue. If the secondary heat exchanger is broken, it may be time to install a new furnace to replace your old unit.

What Do I Do If My Furnace Is Leaking?

If your furnace is leaking, call a professional heating and cooling company to diagnose and fix your problem. Your furnace is an expensive investment, so attempting to repair the issue yourself could result in creating even bigger issues and expensive repairs.

Furnace Repair in Montgomery County & Frederick County, MD

GAC Services offers furnace repair in Maryland. Located in the town of Gaithersburg in Montgomery County, we also service Frederick County, MD and other communities around us. Our award-winning HVAC technicians will be able to diagnose and repair your furnace in efficiently, helping you lower your repair costs and restoring your comfort to your home as quickly as possible.

Contact us online to request a free furnace repair estimate.

Financing Options Available

At GAC, we understand how important a functioning HVAC system is for your home. This is why we offer flexible financing options to help you take care of your new HVAC purchase, so you can get back to taking care of what matters most to you.

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A well-maintained HVAC system can save you from having to invest in costly repairs down the road. Learn more about the priority maintenance services offered by GAC Services.