Tapping Coming From Primary Condensate Line

[Haryy Homeowner]

It's a steady tapping or knocking sound. I removed the side cover from the air handler while it was running and the blower seems fine. No bearing problems or other noticable issues. If I completely plug the end of the condensate line, the sound disappears. Any ideas on what the noise source might be?

[elroho grande]

Sounds like you dont have condensate trap or the trap is not correctly installed. What type of A/H do you have, model number and make might help.

[Haryy Homeowner]

Thanks for the response elroho. I bought the house last summer, the airhandler is older. I'll need to get back in the attic tonight to get the info.

[Haryy Homeowner]

I don't remember seeing a trap up there. Do these EZTraps work?http://www.hvacsolutionsdirect.com/i...files/1711.pdf

[C Combs]

its called air hammering and a trap and tee after the trap will fix the sound

[Haryy Homeowner]

By tee, I assume you mean a vent? I'm on it. Lowes here I come.

[jpsmith1cm]

By tee, I assume you mean a vent? I'm on it. Lowes here I come.

Before you go chopping up your drain line and creating more problems than you solve, two traps in one line is not a good idea.

The first thing I think of is vibration. A few ty wraps or clamps would solve that problem. Putting your hand over the end has the effect of securing the line temporarily.

The next thing would be excessive air pressure causing bubbling or gurgling through the trap. This indicates the need for a professional to properly diagnose and remedy the problem.

[Haryy Homeowner]

Thanks so much. This is all very helpful guys.
I can say that the problem is not from vibration. That's what I had originally hoped was the cause. I've checked for that.
I guess it's possible that my unit has an internal trap. I'll have tio figure out how to access that section of the unit.
Would excessive preesure cause air to be blowing out of the condensate drain line?
Can I test for excessive pressure by simply opening up the duct on the discharge of the blower and if the tapping stops, I'll know that's the problem?

[jpsmith1cm]

Thanks so much. This is all very helpful guys.
I can say that the problem is not from vibration. That's what I had originally hoped was the cause. I've checked for that.
I guess it's possible that my unit has an internal trap. I'll have tio figure out how to access that section of the unit.
Would excessive preesure cause air to be blowing out of the condensate drain line?
Can I test for excessive pressure by simply opening up the duct on the discharge of the blower and if the tapping stops, I'll know that's the problem?

A single trap is all that is required in a drain.

Testing for air pressure requires a manometer.

[jpsmith1cm]

its called air hammering and a trap and tee after the trap will fix the sound

C Combs,

Please read the AOP forum rules.

You have the post count, so apply for Professional Membership to gain access to the Technical Forums.

[Haryy Homeowner]

There was no trap in the condensate drain line. I installed a trap and vent and the knocking 's gone. Thanks.