water system and grrrumps

Joined
18 Mar 2010
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70
Have just replaced my fresh water pump with a new Jabsco (par 2.9) water pump. Does anybody know how often I should expect the pump to operate to maintain pressure when the taps are closed? At present I get a grrrump about every 25 seconds - is this OK or should I look for leaks, air locks etc. Advice appreciated!
 

ghostlymoron

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9 Apr 2005
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9,889
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Shropshire
With no taps open, your pump shouldn't run at all. You've got a leak somewhere, mate. Or airlock. The airlock should dissipate if you open the furthest outlook for a few minutes.
 

prv

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29 Nov 2009
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37,363
Location
Southampton
With no taps open, your pump shouldn't run at all. You've got a leak somewhere, mate.

+1

Ours used to run unbidden for under a second maybe once a day - no water system is 100% pressure-tight. It's now slightly more often, perhaps three times a day, I assume due to the one-way valves in the pump wearing slightly and leaking back. If it gets much more I'll see about fixing it.

Every 25 seconds means a leak.

Pete
 

theoldsalt

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Joined
24 Nov 2010
Messages
2,115
Location
Bristol
Have just replaced my fresh water pump with a new Jabsco (par 2.9) water pump. Does anybody know how often I should expect the pump to operate to maintain pressure when the taps are closed? At present I get a grrrump about every 25 seconds - is this OK or should I look for leaks, air locks etc. Advice appreciated!

Did you have a frequent "grrrump" with the old pump before it (presumably) failed or is this only since fitting the new pump ?
 
Joined
18 Mar 2010
Messages
70
Yes - 5 second or less grrrump- so we are improving. Took the pump apart which was old and because refurbishment was going to cost c.£30 decided to replace.
 

cpedw

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1 Jun 2001
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1,253
Location
Oban
Last season our water system started doing this. After making sure there were no leaks, I decided the pump's valves (it's 29 years old) were giving up. SO i replaced it with new pump. That didn't sort it so I tried another new pump. No change. But there was still no sign of external leaks. So I installed this just upstream of the pump inlet. No further problem.

I should have complained about the pumps but I got one from the For Sale on here (2nd hand but unused) and when the second let me down I was unsure what the problem was so it had been dismantled before I resolved the issue.

Derek
 

duncan99210

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29 Jul 2009
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6,325
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Winter in Falmouth, summer on board Rampage.
The idea of a pressurised water system is that the pump runs as soon as the pressure in the system drops below a pre set value in order to bring the pressure back to that value. The pump will not need priming, as the supply pipe will be full of water, as will the pump and that will remain the case until the tank is empty. With a brand new pump in the system, something is allowing water to escape in the pressurised part of the system, thus causing the pump to run to bring g it backup to pressure.

You don't say if you have a hot water tank fitted in your system: if you do, it will have a pressure relief valve fitted to it. The Valve may be opening to allow water to escape because the pump pressure is too high for it. Some relief valves vent to the bilge, others feed any water back into the supply tank. You could therefore be losing pressure to the relief valve but would not see a leak as the valve doesn't drain into the boat but into the tank.
 
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