Hi there - I had 2 Mitsubishi cooling ceiling units installed in my home last October. Didn't start using them until April.

After the first few days of use in April, they started making strange "whooshing" sounds - as if air, gas, or liquid were swooshing around up there.

The company that installed them has come to our home 4 times now and can't figure out the cause. It's been close to 3 months now.

I looked in our attic today and noticed that the condensate drain pipe is almost totally full of water. Went outside to check the end of the drain pipe, and it's not draining - just a few drips occasionally.

The drain pipe in the attic winds around all over the place (the 2 units are on opposite sides of the house), and not at a very strong slope down for gravity to drain the condensate.

I'm wondering if the condensate pipe is not draining, and that is somehow causing the noise. There is also a mildew smell often now when I run the units. I'm wondering if the condensate pipes need to be more sloped, or if we need an in-line pump installed.

But shouldn't the techs who installed the units (and who have been here multiple times to determine the problem) know if that is the case?? I'm certainly no expert. Any thoughts??

 

Are you talking about mini splits ?

 

Yes, ceiling cassettes...

 

It certainly sounds like they are getting filled with condensation. It's very easy to pinch the clear tube drain line too. The drain tubes cannot run above the wall mounted unit.

Since the drains are gravity fed.... they do need to run downhill. A condensate pump will only help if it's below the wall mounted unit.

 

They are ceiling units. Not wall mounted.

 

PJmax, They are ceiling units. Not wall mounted.

 

Ok.... they are ceiling mounted. The condensate line can't go above the units.

Some units have condensate pumps built in. I'm wondering how they expect ceiling mounted units to gravity drain.