Water pump pulsating

[mick butterworth]

Have just connected a diafram pump into my water system its got a pressure switch on it .When I turn on the tap it works as expected but when the taps turned off the pump pulsates the jabsco water filter is all that's connected in line. ,how do I stop the pulsating any ideas. mick

 

[Sinbad1951]

Pulsating can be caused by a number of factors.
1. Open taps and let the water be pumped thru for 20 secs to make sure there is no air in the pipes.
2. Check every connection in the pipe to ensure there are no leaks. Its possible that you have a pump with a 40psi (quite normal on new pumps) pressure switch. If possible replace the switch for a 20psi one. It will be more than adequate and wont try to force your pipework apart.
3. Check the body of the pump to ensure that you have no hairline cracks in it which appear under pressure. Altho rare this can happen around the one way valves.
Start with number one and if it doesnt resolve problem move onto number 2 etc

 

[VicS]

Or the one way valves in the pump might not be seating properly, allowing the pressure to leak back through the pump.

You dont say if its a brand new pump or a previously used one which might be in need of a service kit.

 

[mick butterworth]

the pump is brand new 30psi ive run the tap fora few minuets to bleed the water filter (no sign of air all removed) the only place there can be leaks is around the water filter fittings if the pipework is disturbed could bypas jabsco filter and see if it helps mick

 

[VicS]

When you say filter i assume yo mean a filter on the pump inlet to prevent debris from the tank getting into the pump ?

Its the outlet, the pressurised pipework, you need to check for leaks

 

[mick butterworth]

its a inline filter fitted behind the pump all fittings are secure between the pump outlet and the taps

 

[vyv_cox]

As VicS says, there should be a strainer at the pump inlet. This is standard practice, I have one for every pump on the boat (toilet, refrigerator coolant, domestic, shower) The domestic water pump often collects debris from the tank, e.g. copper corrosion product from the suction pipework, silicone blobs from the inspection hatch, bits of stuff that come in with the water. I cannot see the purpose of a filter after the pump.

If you are absolutely certain that there are no water leaks, it takes a surprisingly small one to make the pump run, then it is very likely that you have debris in the pump valves. Even a hair is sufficient to prevent the valves from seating properly.

 

[Sinbad1951]

Mick
You need to isolate the poential problems.
I suggest you remove the outlet pipe from the pump to the tap. In its place attach a short run of tube/pipe with a stop cock on it, ie like a washing machine plastic on/off. Once you have done this, run pump and have the new valve closed. The pump should not cycle. If it does then the problem is downstream from your new peice of pipework, so its either the pump itself or you are sucking air in between the tank and the pump.
So next, get another piece of pipe and attach it direct from your inlet on the pump to the outlet on your water tank avoiding filters and other connections (there should be none), if the pump still cycles then the problem can only be the pump itself.

 

[VicS]

its a inline filter fitted behind the pump all fittings are secure between the pump outlet and the taps

As VicS says, there should be a strainer at the pump inlet. ,,,,,,
,,,,,,..................................................... I cannot see the purpose of a filter after the pump.

If by "behind" the pump you mean after the pump then that's OK for any sort of water purification filter but there really should also be a strainer on the inlet to the pump for the reasons given

Tiny leaks are what we are looking for rather than "security" of the connections. If genuinely no leaks then its debris in the pump valves that is the most likely cause as Vyv says. Quite possible if you have not fitted an inlet strainer

 

[VicS]

Mick
You need to isolate the poential problems.
I suggest you remove the outlet pipe from the pump to the tap. In its place attach a short run of tube/pipe with a stop cock on it, ie like a washing machine plastic on/off. Once you have done this, run pump and have the new valve closed. The pump should not cycle. If it does then the problem is downstream from your new peice of pipework, so its either the pump itself or you are sucking air in between the tank and the pump.
So next, get another piece of pipe and attach it direct from your inlet on the pump to the outlet on your water tank avoiding filters and other connections (there should be none), if the pump still cycles then the problem can only be the pump itself.

upstream!

 

[vyv_cox]

Sorry, I was not including a charcoal type purification filter when I wrote that I cannot see the purpose of one. We have a Seagull IV filter immediately adjacent to a dedicated drinking water supply but no filter on the main tap used for washing etc.

 

[ghostlymoron]

It can take a very small leak to produce an annoying burp from the pump. A leaky tap dripping once every few minutes can disturb everyone's sleep.

 

[BlueChip]

Check for drips on the PRV on your calorifier, turn the wheel a few times to dislodge any dirt on the valve seat.

 

[RupertW]

If you have a cockpit shower then check that - both pipe and stopvalve. That was the one leak I forgot about and caused the pulsation.

 

[greeny]

Maybe I've mis understood the problem but is this not why we fit accumulators in the water system - to give some capacity and help stop the pump cutting in and outlike you describe. Without one fitted the system pressure will drop dramatically with a tiny leak back past the nrv,s etc. Do you have one and is it working?

 

[Sinbad1951]

Downstream! Between the pump and the tank. :disgust:

 

[vyv_cox]

Maybe I've mis understood the problem but is this not why we fit accumulators in the water system - to give some capacity and help stop the pump cutting in and outlike you describe. Without one fitted the system pressure will drop dramatically with a tiny leak back past the nrv,s etc. Do you have one and is it working?

My Sadler was built without an accumulator. It worked perfectly well but the noise was annoying every time the tap was turned on. I retrofitted one when the boat was maybe 12 years old.

 

[ex-Gladys]

My Sadler was built without an accumulator. It worked perfectly well but the noise was annoying every time the tap was turned on. I retrofitted one when the boat was maybe 12 years old.

Rubber under the pump feet is a marvellous thing

 

[mick butterworth]

gona have to wait till the weekend to have another look at it ,the under sink filter fitted to the tap is water tight and take out the other jabsco filter to see if it makes a difference, the pump is fitted with rubber feet as standard

 

[mick butterworth]

stripped all the pipe work out and replaced all connections, left out the jabsco filter and fired it up. one pulse every 25 minutes (the tap dribbles very slowly) unless it is turned off with force . maybe now i can get back to rewiring the lights