Said It Here

Why is water pooling inside my furnace?

Water leaks in a furnace usually stem from internal issues like condensation drainage problems or components hidden behind the side or plastic panels. This unexpected pooling stops people from safely running their heating system without constant worry or hearing sloshing sounds from the fan.

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

  1. 1
    Checking and clearing the condensate drain and pump
  2. 2
    Replacing the collector box and gasket
  3. 3
    Applying red RTV silicone sealant to fix leaking gaskets
  4. 4
    Cracking the casing to drain the accumulated water
  5. 5
    Checking intake and outtake pipes for blockages
  6. 6
    Looking for clogged condensate lines or traps

In their words

Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.

r/hvacadvice2 people · September 2026

“Wife noticed some water on the floor by the corner of our furnace this morning.”source ↗

Senior-Pain1335 · r/hvacadvice · 1 upvotes

“It def seems to me it’s coming from behind the black plastic. And it’s basically centered from the distance to either edge.”source ↗

Senior-Pain1335 · r/hvacadvice · 1 upvotes

“So first year turning the furnace on at this place and it has been giving me a hassel all week.”source ↗

“I just was checking the furnace room and heard a bit of sloshing under the noise of the fan running. So I turned off the furnace, popped the side panel to find some water pooling inside and the fan feeling warm to the touch.”source ↗

Unusual_Notice_5494 · r/hvacadvice · 1 upvotes

Where this came up

People with this problem also raised