Why is my furnace leaking water?

It’s perplexing. Furnaces are supposed to create heat, right? Then why the heck is it leaking water!?

Most likely, it’s a condensation leak. This commonly happens in high-efficiency (90%+ AFUE) furnaces, which create condensation as they run.

You need to get a furnace technician fix this problem soon, or the water could damage electrical components in your furnace. It can also cause water damage in your home if your furnace is in the attic.

That’s really all you need to know.

But if you’re curious, read on. We’ll explain why a high-efficiency furnaces creates condensation and what’s causing the condensation leak.

Why high-efficiency furnaces create condensation

Do you know what makes a high-efficiency furnace “high efficiency”?

For one, it has 2-3 heat exchangers instead of one. This allows the furnace to extract more heat from the combustion gases, reducing run times as a result.

There’s a problem with this though.

As the the heat exchangers extract more heat, the combustion gases cool and condense into a liquid (condensation). That water has to go somewhere. And right now it’s pooling around the bottom of furnace.

But why is that?

Here are a few possible suspects.

3 common causes of condensation leaks for high-efficiency furnaces

  1. Clogged or broken condensation line
  2. Clogged or rusted out condensation drain
  3. Malfunctioning condensate pump (not every heating system has one of these, but if yours does, and it’s malfunctioning, condensation can’t be removed properly and instead leaks out of the furnace)

Unfortunately, these aren’t problems you can fix yourself.

Get a furnace repair technician to diagnose the root problem and fix it as soon as possible.

Need a furnace repair tech in the Kansas City area ASAP?

Why not contact Santa Fe Air Conditioning and Heating to repair your furnace?

We offer upfront pricing, so you’ll know how much the repair will cost before you commit and we guarantee our work for 365 days.


Santa Fe Air Conditioning and Heating serves the Kansas City area.