Finding Plumbing Issues Early

Leaking Furnace? 3 Common Causes Of Water Leaks That Have Nothing To Do With Your Furnace

by Chris Bowman

If you've recently noticed water lying around the base of your furnace or a steady trickle of water running from your furnace to your drain, you're no doubt concerned about what might be wrong and already worried about the repair bill. A leaking furnace can signal that there's a problem with your secondary heat exchanger, which is an expensive fix. Fortunately, though, most causes of water leaks linked to your furnace have nothing to do with your heat exchanger or even your furnace, and they're relatively easy to fix. Following are three common causes of water leaks that have nothing to do with your furnace. 


High-efficiency furnaces create a great deal of condensation that normally gets whisked away from your unit via a network of pipes that lead to your drain. If the pipes are damaged, broken or clogged, water may back up into your unit, and it may appear as if the water is coming from underneath your unit. Regular efficiency furnaces may also have condensation issues if your exhaust pipe is not the right size. Improperly sized flue pipes allow water to condense on the inside of the pipe and trickle back down to your furnace.


If your furnace has a humidifier attached to it, your leak may actually be the direct result of a faulty humidifier. While the leak isn't coming from your furnace in this case, it will appear as if it is. Your humidifier can also leak water inside your furnace, which can cause a great deal of damage. Since a leaking or faulty humidifier can cause damage to your unit, it's vital that you have this problem fixed by an HVAC technician right away. 

Air Conditioner

Some air conditioning units are installed so that they share a drain pipe with the furnace that serves the home. If you notice water coming from your furnace while you're running your AC, this is likely what's going on in your case. A block anywhere along the drain pipe can cause water runoff from your AC unit, which is perfectly normal by the way, to back up and leak from your furnace. 

As you can see, there are several reasons why it might look like water is leaking from your furnace. Since some of the reasons can cause damage to your unit, it's important that you have your furnace serviced right away by Buchner Bernie Inc or your local heating contractor once you spot a water leak.