It’s always better to address an issue before it becomes a problem. An unchecked furnace water leak can lead to more costly repairs down the road; homeowners should never overlook it.

Causes Of Furnace Water Leaks

Condensation Leaks

A condensation leak can be the cause of two things: damage/clogged tubing or a floor drain clog. If the tubing that aids the draining is damaged or clogged, this is where a leak occurs. If not the tubing, then perhaps the floor drain itself is clogged.

Keep in mind, condensation should only occur with a high-efficiency furnace, not a standard-efficiency furnace. To determine if you have a standard-efficiency furnace, take a look at the exhaust pipe. A standard furnace has a metal exhaust pipe, and should, therefore, not condensate.

Broken Humidifier

If none of these components is the problem, then leaking may be coming from inside your furnace—specifically the humidifier. Usually, if you get routine maintenance, a professional technician will be able to detect a leaking humidifier before it becomes a headache.

A leaking humidifier can do extensive damage to the inside of your unit and cause further problems such as damages to your walls or floors, and even mold growth.

Secondary Heat Exchange

A furnace with a high-efficiency of 90% or higher will have both a primary and secondary heat exchanger.

Traditionally, as the combustion exhaust exits the primary heat exchange, it will move into a secondary heat exchange; this is where more heat is released from the flue gas, and in turn, water vapors forms.

How to fix a furnace Water leak

If you notice an unusual amount of water coming from your furnace you should do your best to mitigate the issue. Turn off your furnace as soon as possible.

There should be a switch in the furnace room that will do this.  Clean up and dry up as much of the water as possible. If your filter is dirty, remove it and replace it with another. Once everything is dry you can do your best to determine where this water is coming from. Most likely in all situations you should call your local furnace technician but, in this case, you will be able to better describe your leaking water issue. To fix your furnace’s water leak, the first thing you’ll need to do is find the source of the leak. Different types of leaks will show up in different places in your furnace.

For example, if your humidifier is leaking water from the inside, then it’s likely due to the condensate drain line or drain trap inside the furnace.