Why Is My Furnace Leaking Water?
3 minutes read

Why is my furnace leaking water?

Published by Steven Weiland

You may be asking yourself, why is my furnace leaking water? There are a variety of reasons that a furnace may be leaking water. Among them are condensation, your furnace humidifier, a clog, or an issue with your secondary heat exchanger. Recognizing what is wrong is crucial to addressing the problem. Some leaks may be small fixes, while others might need to be addressed urgently in order to save the integrity of your furnace. Below are some of the most common problems associated with a leaking furnace.


The most common reason that furnaces leak is because of condensation. Some furnaces have cool exhausts which draw condensation. When this builds up, it typically drains down a conduit out to of a drain on the floor. However, sometimes these drains become clogged, and so the conduits leak. The line may also have a break in it, which can cause leaking from condensation. This is usually an easy fix—either fixing the line or unclogging the drain.


Sometimes when you fail to properly maintain your HVAC system, your humidifier may encounter problems such as a clogged filter or water pressure that is too high. Humidifiers are often connected to your furnace, and leaking from the humidifier may cause you to believe that your furnace is leaking. The best way way to prevent leaking humidifiers is with regular HVAC check-ups with a heating and cooling specialist.

Internal Drain

The furnace and the air conditioner in your home may share a common drain. If and when the drain becomes clogged, the drainage from your air conditioner may be rerouted to your furnace, causing it to leak. If this goes undetected for too long, it can cause serious damage to your furnace, so make sure to check regularly for leaks.

Heat Exchanger

This is probably the most expensive problem on the list. Keep your fingers crossed that this isn’t the issue. In some cases, this might even require a whole new furnace. The secondary heat exchanger is a stainless steel component of your furnace that extracts heat from exhaust gasses. When this becomes compromised, it can cause water to leak from your furnace.

Regardless what the problem is, you’ll want to get it checked out sooner rather than later. Of course, preventative measures are the smartest move—regular maintenance, changing filters, and keeping an eye on things. But should you run into a leaky furnace, call our team of HVAC specialists at Heatmasters.

Courtesy of Angie’s List

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