quiet circulation pump
#1
02-17-10, 02:08 PM
quiet circulation pump
I have a couple of grundfos UP15-29SU stainless circulation pumps in my radiant floor heating system. Unfortunately, they're pretty loud, and I can hear their whine throughout the house when they're in operation. Any recommendations on quieter alternatives? Taco? Laing? These are AC pumps.
cheers, Grant
cheers, Grant
#2
02-17-10, 02:27 PM
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Look into Taco 007 Cartridge circulator It an equivalent to your circulator. I'm using 2 of them right now and they are quiet.
TACO - HVAC
TACO - HVAC
#4
02-17-10, 02:43 PM
Hmm - what does cavitation noise sound like? The flow rate _seems_ reasonable - several gpm, and there's about 2 feet of head in the system. It really sounds more like a whine than a burble. I have another grundfos pump in a solar loop, though it's a 3 speed cast iron unit, which is much quieter.
Grant.
Grant.
#5
02-17-10, 03:03 PM
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Where and how are you measuring that 2-feet of head?
Pump cavitation often sounds like there are loose marbles inside the pump - not a whine. It occurs when the absolute pressure at the pump's suction is lower than the vapor pressure of the water - causing local vapor pockets (boiling) which then colapse.
Pump cavitation often sounds like there are loose marbles inside the pump - not a whine. It occurs when the absolute pressure at the pump's suction is lower than the vapor pressure of the water - causing local vapor pockets (boiling) which then colapse.
Last edited by Mike Speed 30; 02-17-10 at 03:26 PM.
#6
02-17-10, 03:10 PM
A whine could be not enough head. If there is a valve on the discharge side of the pump somewhere close it down some and see if the noise goes away. That would mean the pump is over sized.
#7
02-17-10, 03:10 PM
Two feet is a guestimate - there's about one and a half feet vertical distance between the pumps and the floor that the pex tubing is warming. Piping is 3/4" copper to 7/8" pex, loop lengths of about 150'.
Grant.
Grant.
#9
02-17-10, 03:14 PM
I was thinking the pump might be oversized - it's a 1/25 hp model, whereas I would think that something like the 1/40 hp ones would be more reasonable given the size of the system.
There is a valve on the discharge side of the pump, so I'll try closing that and seeing if that makes any difference. If this does cut down the noise, is it reasonable to operate it like this, or should the pumps be switched out for less powerful ones?
Grant.
There is a valve on the discharge side of the pump, so I'll try closing that and seeing if that makes any difference. If this does cut down the noise, is it reasonable to operate it like this, or should the pumps be switched out for less powerful ones?
Grant.
#10
02-17-10, 03:29 PM
Closing the valve is creating artificial head. It can operate like that but it does change the flow. I would get the radiant loop near the max temperature it was designed for and measure the supply and return temps and the difference (Delta-T) should be between 15 - 20f. If you know what the delta-T was on design use that number.
#11
02-17-10, 03:34 PM
Hmmm. I've got an equivalent length of about 90' of 3/4" pipe, and 140' of 7/8" pex. According to a hazen-williams calculation, for 5gpm, this is about 8' of head loss in the copper, and about 2.5' for the pex, for a total of 10.5' of dynamic head.
Grant.
Grant.
#12
02-17-10, 05:15 PM
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OK, but did you try throttling the pump's discharge valve as suggested by rbeck? What was the result?
#13
02-17-10, 07:03 PM
I just tried closing the valve on the discharge side of the pump, and it really makes no difference in the noise, other than what I'm presuming is cavitation noise just as the valve is almost fully closed (it gets somewhat louder). I'm beginning to suspect that these pumps are just a little on the loud side.
Grant.
Grant.
