Grundfos Circulator

Docfletcher

My indirect water heater circuit is making more noise than ever. The (UP 15-42 FR) circulator is currently mounted horizontally, 3/4" flange in and 1 " out. I want to change the circulator position to vertical hoping the noise will go away.

The noise I believe is directly related to water flow. Shutting the ball valve abruptly and immediately opening it once or twice causes the noise to go away compleatly for a minute or two. Then noise returns. Could the 3/4" flange in and 1 " out be causing the noise? If so, I could order a flange kit to make both in and out the same and try that before going through the trouble of remounting the circ to vertical. Thanks for your help.

hot_rod

Could it be some air bubbles in the circuit. Air can present all sorts of unusual sounds. Got a good working air separator on the system somewhere?

Docfletcher

No air separator like a spirovent JR. If I mount the circ vertical it most likely would prevent air from getting trapped. The circuit does have a spirotop vent, but it installed was just to remove bulk air when water was added to the circuit at startup of the new indirect.
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Henry

It sounds like cavitation. You ned at least 5X the diameter straight pipe before the pup and minimum 3X after. We have standardised with 5X before and after.

Docfletcher

Thanks, I get it. So the 3/4" pipe in and in and 1" out should not matter once I make for longer pipe lenghths?

Zman

Are you "Pumping Away" from your expansion tank?

Docfletcher

Not 100% sure. Older system so probably not. Tank is mounted at the system return and the circ is currently on the system supply very close to the boiler. Before the indirect was changed the circ was vertical and there was no noise. So I think I need to return it to vertical.

HVACNUT

Is the circulator motor itself horizontal. If the circulator motor is mounted vertically, motor facing down, never. Motor facing up, system pressure must be set to min. 20 psi.
What is the system pressure?

Docfletcher

18 psi @ 105F Which seems a bit high to me considering the auto fill is set at 14psi.

hot_rod

I'm not clear on what you mean by vertical? the piping run, or motor orinatation?

They will actually run in ANY position, but they are happiest as indicated.

Noise is usually air related, unless it is a squeal from a damaged bushing.

Docfletcher

I'm speaking of changing the circulator position and it's piping to vertical. Currently the circulator and piping are horizontal. The motor is also horizontal.

GroundUp

A vertical piping arrangement is not going to make any more or less noise than a horizontal piping arrangement. Odds are you are trapping air somehow, and you need to take care of the air infiltration issue before you worry about moving the circ. Is the Spirovent still in place? First you say there isn't one but in the next breath say there was one installed- which is it? The pipe sizes will not play a role in the noise either, and unless there is a street 90 in the inlet side flange I find cavitation hard to believe also. My money is on air bubbles

Alan (California Radiant) Forbes

Increase the pressure to 25 psi with the pump running which reduces the size of the air bubbles and makes them easier to move around.

If that doesn't work, add some dishwashing detergent to reduce surface tension which will do the same thing.

Docfletcher

Yeah my bad... I should have said a Spirotop vent, just to let air out while filling the indirect.

Circ has been removed/installed 3 times and noise remains. There are 1" unions at the in and out of the indirect, I will check them 1st and move on from there.

I did run at elevated PSI last year but it did not help. I guess I may try Alan's dish soap. Thanks guys...

gennady

If circulator has internal flow check, then most probable it causes the noise. Try to replace it or remove.

Docfletcher

No flow checks in circ... Thanks

Docfletcher

I have found a tiny leak on the low pressure boiler side of the pressure regulator. Looks like it has been leaking for quite a while. .

Docfletcher

Thanks everyone for all the assistance with my noise issue. GroundUp gets kudos and abig fat Cigar for his air infiltration call which looks to be a good call. I fixed the well concealed leak and the noise problem is gone.