Pump problems on the Garn

[hedge wood]

Finally getting close to making heat with the Garn. I put the first 2000 gallons of water today and the PrCln775 and made the first fire in the Garn. Know for the problem I have four heat exchangers so I have four ups15-58fc grundfross pumps on the Garn side of the heat exchangers. I started the four pumps up to mix the water as the chemical calls for and two of the four pumps are very noise. Any ideas?

 

[sdrobertson]

My first guess would be air bubbles. Try starting and stopping the noisy ones to move the air out. You may have to flush them to help move the air pockets.

Edit: The air bubbles may be in the line after the noisy pumps as the water is not circulating and the pump is caveatting and not pushing water.
https://www.hearth.com/econtent/index.php/forums/viewthread/43613/

 

[hedge wood]

They are not noisy all the time. There should not be any air in the line as these are right behind the Garn with a two inch pipe feeding them. I did valve down the two inch return and then opened it up and I could hear the water returning. I wonder if I should take the check valves out of pumps as these pumps are on the open side of the Garn.

 

[heaterman]

They are not noisy all the time. There should not be any air in the line as these are right behind the Garn with a two inch pipe feeding them. I did valve down the two inch return and then opened it up and I could hear the water returning. I wonder if I should take the check valves out of pumps as these pumps are on the open side of the Garn.

Are the flanges situated horizontally or vertically? If horizontal I would pull the checks if the circs are all on/off together. They will self purge better and you don't need them anyhow in that circumstance.

 

[sdrobertson]

They are not noisy all the time. There should not be any air in the line as these are right behind the Garn with a two inch pipe feeding them. I did valve down the two inch return and then opened it up and I could hear the water returning. I wonder if I should take the check valves out of pumps as these pumps are on the open side of the Garn.

If I'm correct then you have 4 separate zones with each having a pump for that zone. 2 of the zones are flowing well and 2 are noisy. The 2 that are noisy sounds like there is a air pocket somewhere between the pump and the air exchanger. It could be in the supply to the heat ex or going back to the Garn. If it is a air pocket, your pump is getting plenty of water but it is not able to move the water around the air pocket so it just spins until it moves the water a little bit so no noise and then it stops flowing and then you get the noise again.

 

[hedge wood]

Once the system is completely done the pumps will not come on and off together that is why I left the check valves in the pumps. The pumps are mounted in vertial position so they should be getting plenty of water. The two inch line comes out of the upper part of the Garn and then elbows down to the floor and then I have a tee and more two inch pipe both ways with pumps mount vertial off that pipe then to the flat plate and then out to the bottom of Garn via a two inch pipe manfold. The other thing I forgot to mention is the pump motors seem very warm to me and the noise seems to be coming from the motors it is a high pitch kind of noise that comes and goes.

 

[snowman49820]

I sometimes loosen the bolts and lightly crack the output flange. That will draw the air out if your bleeder screw on the pump doesn't work.

 

[stee6043]

I picked up a couple of Grundfos pumps last year and didn't install one until this Fall. The one I installed this Fall made all kinds of noise for about 10 minutes upon initial startup. From the noise I figured I had some corrosion on the inside of the pump after it had sat for most of the summer in my basement. After a good few minutes of forcing it to run it quieted right down and has been good to go since.

How long did you run the pumps? Is it a "screeching" type noise?

 

[hedge wood]

Yes it is a screeching noise. I ran the pumps on and off for a couple of hours hoping they would quiet down but they did not. Going out to the Garn barn this morning and run them and see how they sound after they have completely cooled off over night. The pumps are new out box from Pex supply.

 

[hedge wood]

Well today was a better day. Started checking for air in the two inch line and sure enough the pumps were air locked. I though I had all the air out but I did not . Know the pumps are running quiet. Thanks to all for the help.

 

[sdrobertson]

Gas bubbles really hurt my system also sometimes...sorry couldn't resist...

Glad to hear everything is working now.

 

[Gooserider]

What happens if you only run some of the pumps? If you shut off the quiet ones, do the noisy ones quiet down?

It would seem to me like if all four pumps are pulling from the same line, you may be getting enough pressure drop to cause intermittent cavitation in some of the pumps... If shutting some of them down makes the noise change, that would seem indicative to me....

Gooserider