Noisy steam condensate return pump

HawkThua · June 21

Hi there, I need help to identify a problem with my condensate return pump. It makes a noise after it turns off. I don't really how to describe it but it's like a idle big motorcycle engine. It lasts for about 30 seconds.

I disconnected the pump from the condensate reservoir and from the downstream pipe to inspect it and then it started to make that noise.

Any suggestions?

EBEBRATT-Ed · June 22

So it started to make noise after you took it off and re installed it? Are you sure it is seated properly in the housing with a new gasket?

HawkThua · June 22

The pump ran dry for a few hours because the switch got stuck and it didn't turn off, so I tried to inspect the impeller to see if it was damaged (figured I wasn't going to be able to open it so I didn't). I'm not sure but I think it started to do the noise after I took it off of the condensate reservoir.

To me it looks like it is sitting correctly and the pump has less than 10 working hours so I'd say the gasket is new.

Jamie Hall · June 22

Depending on the make and model of the pump, you may have a big problem. Not saying you do, but some of those pumps have water lubricated bearings or seals and if it ran dry for a few minutes, never mind a few hours, they're done.

HawkThua · June 22

But it runs fine. It's after it stops that makes this noise. See this video, the sound is similar to what you'll hear on it

https://youtu.be/t8yDPcawKTE?si=t01Nq_ODfE5OPt7o

Pumpguy · June 22

This is a new one on me. I've been fixing condensate pumps for decades and have never heard one sound like that after it shuts off. Can you tell us more about the pump; brand and model, and maybe some pictures? Can you post a recording of its sounds?

Maybe you have a leaking discharge check valve and after the pump shuts off, water flows back through the leaking check valve with a gurgling sound?

I concur with @Jamie Hall about possible shaft seal damage. All of the condensate pumps that I'm familiar with have a water lubricated mechanical shaft seal, and when these run dry, the seal overheats causing damage to the ceramic and carbon faces which results in a leaking shaft seal.

ethicalpaul · June 22

Maybe it's some pressure or vacuum relieving itself after the pump shuts off

PC7060 · June 22

Reminds me of the sound of a poorly tuned car deiseling after ignition was shutoff. From back when we all had cam driven points that needs to be changed 2x per year.

ethicalpaul · June 22

Well the sound up there wasn't the pump, it was a motorcycle.

Jamie Hall · June 22

https://forum.heatinghelp.com/discussion/comment/1804641#Comment_1804641

Ah yes. I remember those — very late 60s into early 70s. There was supposed to be an idle stop solenoid (and was) which was bit finicky to adjust — and half the mechanics didn't even know it was there. Easy enough to fix even on Quadrajets…

HawkThua · June 22

https://forum.heatinghelp.com/discussion/comment/1804640#Comment_1804640

That's the first thing that came to my mind. The questions are where and why, since it wasn't there before. So in my opinion it comes either from the pump, or from the check valve that's right after the pump.

Any idea on how to check them?

PC7060 · June 22

quadrajet carburetor; that a blast from the past. My first car was a 1970 Buick GS with a V8/quadrajet carb. Really good at turning fuel into exhaust. 😎

PC7060 · June 22

https://forum.heatinghelp.com/discussion/comment/1804600#Comment_1804600

Can you post audio of the actual pump?

HawkThua · June 22

https://forum.heatinghelp.com/discussion/comment/1804648#Comment_1804648

I'll try, on Monday..

Pumpguy · June 22

Unless part of a vacuum return system, the condensate pump's receiver tank should be vented to atmosphere. That would eliminate the possibility of vacuum in the tank.

You might try manually closing the pump's discharge valve right after the pump shuts down. If closing the discharge valve eliminates the gurgling sound, that would pretty much point to a problem with the pump's discharge check valve.

HawkThua · June 27

@Pumpguy After closing the valve for a couple of seconds it goes away

https://drive.google.com/file/d/1e3TzK38NnprMJ4CRElhMmikw_7iiFL0M/view?usp=drivesdk

I can't upload the video from my phone but there is a drive link to it

Pumpguy · June 27

Wow! Why is that pump so noisy? Sure sounds like bad motor bearings to me.

Most condensate pumps are close coupled to the motor, and don't have their own bearings. And, the bearings in these motors are shielded, lubricated for life type. A typical life for these bearings is 10 years.

If you could tell me what the brand and model number is of your pump, I might be able to tell you what parts you need.

I would plan on new motor bearings (or a new motor) and a shaft seal and gasket kit for the pump. This is the perfect time to take care of this. Please don't wait until the start of the heating season and then say its an emergency when the motor fails.

EBEBRATT-Ed · June 27

Or just take it to a motor shop

Pumpguy · June 27

Right @EBEBRATT-Ed, Problem is, motor shops don't always use OEM seals which may not be suitable for condensate pump applications, especially if condensate is very hot, or has high concentration of Amine based water treatment chemicals.

HawkThua · June 28

Actually you can hear a click in the beginning of the video, that is the pump shutting off. The weird noises are from the pipe.

Noisy steam condensate return pump

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