Grundfos JP4 and JP5 booster pumps...noise

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8 Aug 2006
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Customer had a JP4 pump (This is a water supply lifting pump to supply a roof tank from a private water tank in a field fed from a spring), nice and quiet and then it leaked. He bought a JP5 and got another plumber to install it..its VERY noisy. Other plumber is unwell ( he is a friend so its genuine) so I've been asked to try and sort it out.

I suspect the supply is inadequate for the pump as its only in 22mm over at least 30metres, and there is pretty well no head at all, maybe even negative head.

I installed a check valve..made no difference. I'm off back to check flow rates and pressure with my gauges tomorrow. I just wondered if other people know this pump and if they have found it noisy. It does seem to be cavitating so I suspect inadequate supply (It improves slightly when you throttle down the outlet gate valve by a turn or two).

Its a mystery in that the JP4 behaved perfectly until it pi**ed in its pants.

Alfredo
 
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Well..the answer is to install the ejector valve in position one, and to throttle back the outlet regulator which reduces cavitation and keep flow rate at around 16-18 litres/min...which is more than adequate.

Its still noisy, but a lot less noisy.

Not that anybody is interested :mrgreen: :LOL: :mrgreen: :LOL:

Alfredo
 

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