Boat water system pump issue

[Pyramid]

The boat is fitted with a Jabsco automatic water system pump, rated at 25psi that delivers 11 litres per minute for systems up to two taps.
Until recently, when you opened the tap the water would run slowly then the pump would kick in, with discharge rate improved a little and run until the tap was closed.
However, now, when you open a tap (mixer type at basin in galley and basin in the heads) the pump does not continually run, but starts and stops three or four seconds later, but starts again after two or three seconds, then stops again and so on.
When I close the tap the pump stops having brought the system to pressure I assume.
Interestingly, if you open both the galley and heads taps then the pump does run without interruption!
I do think that the pressure though is generally low and only improves when the pump starts - as it should of course but not great. You wouldn't be able to shower with it.
The system is not equipped with an accumulator - the Jabsco pump does not require one and clearly - or not, the system does pressurise! It just does not maintain the pressure consistently when a tap is opened.
Filters checked and clean with no leaks across the system, but then again I'm not losing pressure, that's not the problem There are no obstructions across the system and all hoses - half inch - are good.

I suppose the question is this - even though the pump runs, is it on its way out and exhibiting a loss of ability to retain effective pressure upon opening a tap, thus retaining effective discharge pressure. If this is the case I'll replace it?

 

[RichardS]

It certainly sounds as if the diaghram or the valves on the pump are on the way out. You might well be able to change these for new ones. Look for parts online for your model and see what's available.

Richard

 

[David2452]

Does not require one is not the same as will not benefit from one and I would usually install one anyway. However I suspect on yours is leaking too much back through the bypass and may benefit from a service kit and a possible tweak of the pressure switch.

 

[johnalison]

The new pumps, as you say, ought to manage without an accumulator tank. Although fitting such a tank should cure the problem, I would be inclined to get in touch with Jabsco and see if they have a solution.

 

[VicS]

The boat is fitted with a Jabsco automatic water system pump, rated at 25psi that delivers 11 litres per minute


I suppose the question is this - even though the pump runs, is it on its way out and exhibiting a loss of ability to retain effective pressure upon opening a tap, thus retaining effective discharge pressure. If this is the case I'll replace it?

I assume its a Par max pump although you do not say

I think I would follow David's advice and install a new "valve kit" ( £12 + VAT from Jabsco), but first perhaps inspect and clean the existing valve assembly.

 

[Lon nan Gruagach]

It certainly sounds as if the diaghram or the valves on the pump are on the way out. You might well be able to change these for new ones. Look for parts online for your model and see what's available.

Richard

The pump is multi-diaphragm, poor pressure and flow rate could indicate one or more not functioning. But the pressure switch stops the pump so its not poor pressure (maybe).

Does not require one is not the same as will not benefit from one and I would usually install one anyway. However I suspect on yours is leaking too much back through the bypass and may benefit from a service kit and a possible tweak of the pressure switch.

If it had a leaky valve it would pulse while all taps are closed.

Possible problems are
There is a blockage causing the pressure switch to sense max pressure while flow rate and pressure at the taps is low.
The pressure switch is over sensitive cutting the pump off before full pressure is reached.

If it is this https://www.jabscoshop.com/marine/pumps/pressurised-fresh-water-pumps/31395-0292-par-max-29-pressure-controlled-pump.htm then the switch should turn on at 1bar(15psi) and off at 1.7bar(25psi). Tee in pressure gauge after the pump.

 

[Pyramid]

Yes, it's the Par Max 2.9 Jabsco I have. But there does not appear to be a loss of pressure - as caused by a leak - as the pump shuts down after a few secs and remains off when all taps are closed.
The pressure is low generally though so does this support the likelihood that, when the flow is opened a back pressure builds within the pump, leading to the pump switching off?
Flow drops, pump kicks in again, back pressure builds, pump shuts off, flow rate drops, leading to pump kicking in again as a result of the build in back pressure and so on.
N

 

[wiggy]

I had a similar problem. Solved by removing the little aireation fittings on the spout of the taps and clearing out the incredible quantities of lime scale flakes.

 

[Mark H]

We have the same Par Max 2.9 25 psi pump. The boat had the water system emptied for winterising and we purchased the boat and after refilling the tank, tried to use the water and nothing. I can hear the pump working when switched on at the main fuse panel and suspect there is nothing wrong with it. From reading this thread I now understand the system is pressurised and the pump is designed to come on automatically when one of the taps are opened (as was happening when we sea trialled the boat in November).
I tried opening both taps an switching the pump on and waiting but nothing. I tried sucking on both taps but nothing.
So any ideas how to re pressure the system?

 

[vyv_cox]

We have the same Par Max 2.9 25 psi pump. The boat had the water system emptied for winterising and we purchased the boat and after refilling the tank, tried to use the water and nothing. I can hear the pump working when switched on at the main fuse panel and suspect there is nothing wrong with it. From reading this thread I now understand the system is pressurised and the pump is designed to come on automatically when one of the taps are opened (as was happening when we sea trialled the boat in November).
I tried opening both taps an switching the pump on and waiting but nothing. I tried sucking on both taps but nothing.
So any ideas how to re pressure the system?

Diaphragm pumps do not need priming. If water is not issuing from the taps there is a blockage somewhere, assuming the pump is electrically OK. Does the pump run, i.e. can you hear it clicking? If not, check the electrics. If it runs continuously there is a problem with its internal valves, or possibly it is sucking air on the inlet side. If it runs briefly but no water comes from the taps there is a blockage downstream of the pump. As has been said, the first thing to check is the filters on the taps, which collect debris very readily.

 

[VicS]

We have the same Par Max 2.9 25 psi pump. The boat had the water system emptied for winterising and we purchased the boat and after refilling the tank, tried to use the water and nothing. I can hear the pump working when switched on at the main fuse panel and suspect there is nothing wrong with it. From reading this thread I now understand the system is pressurised and the pump is designed to come on automatically when one of the taps are opened (as was happening when we sea trialled the boat in November).
I tried opening both taps an switching the pump on and waiting but nothing. I tried sucking on both taps but nothing.
So any ideas how to re pressure the system?

I would think the system is completely dry and that you will have to prime it, although the pump is a multi diaphragm design which should self prime up to 1.8m

There should be a filter somewhere in an accessible location in the pump suction pipework. Start by checking/ cleaning that.

If the pump is lower than the water level in the tank try disconnecting, or loosening, the pump inlet connection and allowing air in the pump suction pipework to escape before reconnecting it

Then try switching the pump on again with the taps open.

( dont run the pump continuously for longer than 15 minutes)

More info on line at http://www.xylemflowcontrol.com/files/31X95_32600_43000-1810.pdf

 

[RichardS]

We have the same Par Max 2.9 25 psi pump. The boat had the water system emptied for winterising and we purchased the boat and after refilling the tank, tried to use the water and nothing. I can hear the pump working when switched on at the main fuse panel and suspect there is nothing wrong with it. From reading this thread I now understand the system is pressurised and the pump is designed to come on automatically when one of the taps are opened (as was happening when we sea trialled the boat in November).
I tried opening both taps an switching the pump on and waiting but nothing. I tried sucking on both taps but nothing.
So any ideas how to re pressure the system?

Sucking on the lowest tap on the boat with the tap open and the pump running and the water tank full should work if disconnecting pipes is not so easy.

When you say "nothing" ....... what actually happens. If you're drawing a vacuum then there is a blockage somewhere or a stuck valve in the pump and disconnecting pipes/filters is going to be needed to identify the blockage. If you're not drawing a vacuum but no water is coming out then I suspect that you just have a lot of air in the pipes and so just need to keep sucking for long enough until sound of the pump changes and water appears. You could use a dinghy pump to suck if your cheeks are hurting.

Richard

 

[vyv_cox]

I would think the system is completely dry and that you will have to prime it.

Hopefully the pump is lower than the water level in the tank so try disconnecting, or loosening, the pump inlet connection and allowing air in the pump suction pipework to escape before reconnecting it

My pump is above the tank, maybe up to 50 cm above the water surface. It always primes perfectly well, even at the start of the season after draining at the end of the previous one.

 

[wiggy]

Mine can take up to 5 minutes to prime, I suspect the pimps ain't as good at pumping air as water.

 

[rogerthebodger]

We have the same Par Max 2.9 25 psi pump. The boat had the water system emptied for winterising and we purchased the boat and after refilling the tank, tried to use the water and nothing. I can hear the pump working when switched on at the main fuse panel and suspect there is nothing wrong with it. From reading this thread I now understand the system is pressurised and the pump is designed to come on automatically when one of the taps are opened (as was happening when we sea trialled the boat in November).
I tried opening both taps an switching the pump on and waiting but nothing. I tried sucking on both taps but nothing.
So any ideas how to re pressure the system?

In my view you either have a small leak in the suction side of the water supply from the tank to the pump or the pump has a problem with crud in the valves or a damaged diaphragm.

If the leak of air into the suction side is small it may not show up if there was water in the supply line but would show up when the supply line was drained and only had air in it. This would cause the priming to be less effective and possibly prevent priming all together.

 

[rogerthebodger]

The boat is fitted with a Jabsco automatic water system pump, rated at 25psi that delivers 11 litres per minute for systems up to two taps.
Until recently, when you opened the tap the water would run slowly then the pump would kick in, with discharge rate improved a little and run until the tap was closed.
However, now, when you open a tap (mixer type at basin in galley and basin in the heads) the pump does not continually run, but starts and stops three or four seconds later, but starts again after two or three seconds, then stops again and so on.
When I close the tap the pump stops having brought the system to pressure I assume.
Interestingly, if you open both the galley and heads taps then the pump does run without interruption!
I do think that the pressure though is generally low and only improves when the pump starts - as it should of course but not great. You wouldn't be able to shower with it.
The system is not equipped with an accumulator - the Jabsco pump does not require one and clearly - or not, the system does pressurise! It just does not maintain the pressure consistently when a tap is opened.
Filters checked and clean with no leaks across the system, but then again I'm not losing pressure, that's not the problem There are no obstructions across the system and all hoses - half inch - are good.

I suppose the question is this - even though the pump runs, is it on its way out and exhibiting a loss of ability to retain effective pressure upon opening a tap, thus retaining effective discharge pressure. If this is the case I'll replace it?

As said it looks to me that you have a blockage in the pump output line somewhere. Blockage in the tap filters always gets me scratching my head then SWMBO comes to the rescue.

 

[Mark H]

Thanks for the tips guys. I will try checking the filter for crud, disconnecting the inlet and give that a good suck, and I like the dinghy pump idea too. I am pretty hopeful it will get solved. Will report back!

 

[Mark H]

I went back to the pump and checked all the seals on the inlet and outlet with the pump running. I noticed the outlet had a little droplet of water appear when I applied a little pressure as I went to unclip it so pressed the pipe against the fitting and heard a gurgle as the water started being drawn through the pump and it is now working again without any major interference. What a result and thanks for all the advice!