Pump Squeal - brand new Bell & Gossett series 100 bearing assembly

Ken7878

We had a B&G series 100 pump where the seal was leaking so we replaced the entire bearing assembly with a brand new one. After two days when the pump would shut off it would squeal to a stop. The squeal keep getting louder and louder until it could be heard through out the entire house when the pump would stop.
We took the bearing assembly back and got a replacement. After about two weeks of operation it is doing the same thing plus sometimes it squeals even when running, not just when stopping.

We made darn sure the system was flooded before allowing the pump to run so it never ran with a dry seal.

Any ideas?


Thanks,
Ken

JUGHNE

Does the new 100 replacement bearing assembly require oil like the old ones did? I know things change.

Ken7878

Yes. The bearing assembly came with a small tube of oil. It had three lines on it. You squeeze oil into the bearing assembly oil cup till the level in the tube reached the first line, then you squeezed oil into each motor oil cup, one motor oil cup to the second line and the other motor oil cup to the third line. But the motor was not replaced, just the bearing assembly so it didn't need this much oil, it had already been oiled at the start of the heating season. B&G warns not to over oil the motor.

Ken

JUGHNE

Could your issue be with the motor itself? After motor bushings heat up they could get noisey and upon cooling down seem good. I really liked that pump but as they age there seemed to a variety of problems. And cheap replacements were cheap. Won't last as long as a 100 but were cheap.

Steve Thompson (Taco)

A squeal when a mechanical sealed pump shuts down usually indicates a dry running seal (runs OK when the circ is at speed). This is why the minimum speed of a sealed pump can't go much below 20 Hz for example - the seal looses the fluid film (lubrication) between the stationary and rotating seal components. The lower the system pressure the bigger the problem.

What is the system pressure, where is the expansion located (upstream or downstream of the circ) and are you using any kind of boiler treatment?

Not saying it isn't the motor or bearing assembly but I suspect the seal.

icesailor

There used to be instructions with B&G Series 100 pump seals/Brackets suggesting that you always replace the rubber motor mounts. Because although they always look fine, even on one running for 20 years, the weight of the motor causes the end rubber mount to squash and drop. Especially if the motor is over-oiled. B&G was more interested in the fact that it caused motor to bearing drive couplers to fail. The motor is now misaligned and "wobbles" in its rotation. Which causes the springs to break. Its of my useless opinion that it also sets up vibration and the small vibration causes the ceramic seal to wear unevenly. If you go somewhere and see some dead couplers around, change the rubber mounts. Ir change the pump. A Lucky 7 pump is cheaper than the sum of the repair parts.

Its also very easy to damage the seal when swapping out impellors. If the impellor gets bent from removal from the old, it will be out of balance on the new bearing/seal assembly. Another reason why you see so many red flanges with green pumps connected to them. And the green "Lucky 7" pumps connected to them. With the red rubber gaskets that leak and the black synthetic rubber square cut O-rings thrown away.

Ken7878

Thanks to all for the replies.

Steve Thompson:
The system is at 12 PSI static and cold. The expansion tank is large and the pressure only goes up about one (1) psi at temperature (190 DegF).

The expansion tank comes off a B&G inline air seperator right before the suction side of the pump.

icesailor:
The rubber motor mounts were changed a year or a year and a half ago when the coupling broke. We try not to over oil the motor because of the motor mount issue.
The impeller is off the bearing assembly that started leaking, it is plastic.

One other thing to mention:
After the first new bearing assembly started to squeal we took the whole motor/bearing assembly out as a unit and set it on a table, it was still hot from being in the system. When I slowly turned the impeller by hand and then let it come to a stop it squealed but after about two minutes on the table it had cooled down a bit and then when I turned it, it did not squeal.
But we replaced that first new bearing assembly anyhow and now the second new one is squealing. It is still in the system.

JUGHNE:
The fact that is stopped squealing when it cooled down makes me feel that it is the bearing assembly and not the motor because the motor probably wouldn't change temperature that quickly where as the bearing assembly would. But I don't want to fool myself to the true problem and end up spending much time and money.

All three bearing assemblies (the one that was leaking and the two new replacements) were aluminum with carbon/ceramic seals.

Any other thoughts?

Thanks,
Ken

unclejohn

At this point some pictures would help. You are missing something, two bad bearing assembles very unlikely.

Paul48

Pop the cover that the flip top for oil, on the bearing assembly is. The square cover. Put a tablespoon of oil in there.

bob_46

If the motor is an older one it has a centrifugal starting switch . When you turn the pump off as it slows down do you hear a click and then the squeal ?

hot_rod

bob said:

If the motor is an older one it has a centrifugal starting switch . When you turn the pump off as it slows down do you hear a click and then the squeal ?

excellent point, bob

SWEI

What kind of oil are you using on these bearings?

nicholas bonham-carter

Has Joni "let's make 'em squeal" Ernst been near this system?--NBC

steve58

I know this is old topic, but seems to end without resolution and I am having same squeal issue. Tried to private message ken7878 but seems to have not been on here since Jan 2015 and may not get it. Maybe was resolved by direct messaging between him and one of posters in thread, if so please come forward... TIA

HomerJSmith

You can maybe use a mechanic's stethoscope to isolate the source of the sound. The ceramic seal is lubricated by the system water. You might try to lubricate the centrifugal weights and circular plate on centrifugal starting switch with electrical grade silicone spray. Be sure and spray half a can, like not. Light spray only.

Toad

Has anyone managed to determine root cause/solution to this? We recently had a brand new B&G 100 installed and are getting that short screech at boiler burner shutdown. Thanks.

HVACNUT

Has the new pump been properly oiled?
Why was a wet rotor pump not used?
In residential applications, the B&G 100 is kind of obsolete. By about 30 years.

Toad

Had comparable Taco 110 that worked well for 15+ years. When we tried various higher RPM, lower volume/higher head wet rotors we had various noise and flow issues. So went back to same pump profile. And yes, believe it was properly oiled.

HomerJSmith

Series 100 circulators were used with zone valves because it had a flat pump curve, albeit low head. The Series 100 has wicking in the pump section to keep oil on the shaft. Is it there?
A manufacturing defect? It happens. Did you talk to B&G?