Jabsco Par Max 4 fresh water system flow problem

[Skylark]

I'm still having fresh water flow problems since replacing the failed pump regulator valve. It seems impossible for the man-in-the-street to contact Jabsco directly but the parts supplier has been helpful and Vyv has been super-helpful by PMs but I'm running out of ideas, hence looking for a fresh pair of eyes.

My Beneteau has a Jabsco fresh water system and the Par Max 4 pump is fitted with a 30 psi cut off valve. It is not possibly to get a replacement cut off valve as these are dedicated to the Beneteau system (seems a bizzare response) so I was supplied with a 25 psi valve as a replacement. The lower pressure valve for this pump is 10 psi and the accumulator should be set at 2-3 psi lower than this, according to the spec and instructions.



With the accumulator set to 7-8 psi, per the spec, with any tap fully open, the pump runs for approx 1 second, off approx 2 seconds. But, big but, by the time that the pump cuts in, the flow out of the tap is barely more than a dribble. If I completely vent the accumulator, the pump runs for about 1/2 second, then off for 1/2 second, repeat. The flow is no more than a dribble before the pump kicks in again.

I've video'd this and sent it to the (well known and respected) parts supplier. In turn, they have sent it to Jabsco who have now said "set the accumulator to 13 psi. This contradicts their spec sheet for the 25 psi valve but I'll try it when I next visit the boat.

Does anyone with fresh eyes recognise these symptoms and know how to restore proper (prior to the valve failing) pressure and flow?

Many thanks.

 

[Boater Sam]

The resistance to flow is almost equal to the pump delivery pressure. So either increase the pressure or reduce the resistance to get more flow.
Is the switch in the pump under the blue cover adjustable? Screwing in increases cut off pressure.
Is there a resistance in the pipework or the inlet to the pump? Kinks? Blocked inlet filter?

You could fit a Square D or similar separate pressure switch with adjustable on and off settings into the outlet pipe anywhere and connect the wires from your original switch to it. Just a bit of plumbing.

 

[PCUK]

Have your basins got standard domestic taps or some odd things dedicated to your boat?

 

[Skylark]

@PCUK all of the taps and shower heads are same as domestic.

 

[JOHNPEET]

Ok, from your post above, my understanding is that the pump cut in pressure is 10psi and cut out pressure is 25psi. With the accumulator air cushion set to 7psi, there is no way that the pump is raising the system pressure to 25psi in half a second!
Or have I misunderstood something above?
It would be really useful if you have a pressure gauge in the system somewhere, so that you can see exactly what is going on.
If I have got the above correct, I suspect the new pump switch to be faulty

 

[Skylark]

Thanks, @JOHNPEET your understanding of my description is correct. My timing of the frequencies isn’t accurate I’m afraid, more of an indication. I have two videos which are useful but I don’t think that I can post iPhone videos.

Here are a couple of stills from the video. Take a look at the water flow hitting the bottom of the sink. At high flow, there’s quite a splash. It’s only a dribble at low flow.



Any suggestions for inserting a pressure gauge, without cutting into the standard pipe work etc?

 

[JOHNPEET]

The sequence of events for using the system would typically be as follows:
System lying at rest, fully pressurised to 25psi
Turn any tap on
Water is drawn off, system pressure drops slowly as the water being drawn off is supplied from the accumulator.
System pressure will continue to drop until the accumulator is empty of water and the pressure drops to 10psi (cut in pressure for pump)
Pump cuts in at 10psi, system pressure rises to a balanced position based on demand and pump delivery capacity. Water continues to be drawn off at the tap.
Turn tap off.
Pump continues to run whilst the accumulator refills and the system pressure rises to 25psi at which point the pump will stop - pump cut out pressure.

So you will see a drop in system pressure (as can be seen at the tap) during the time between opening the tap and the pump cutting in. I think increasing the accumulator cushion to a few psi above the cut in pressure will reduce the time it takes the pump to cut in at the reduced pressure . Basically, the accumulator will be empty of water at say 13psi at which time the system pressure will drop very quickly to the pump cut in pressure.

Permanently installing a pressure gauge would be useful in this instance and for future monitoring. If you don’t fancy going the permanent route, a test gauge could possibly be modified to fit on one of the taps. Something like this:
BES.co.uk | Next Day Delivery On 15,000 + Plumbing Supplies

 

[billskip]

The sequence of events for using the system would typically be as follows:
System lying at rest, fully pressurised to 25psi
Turn any tap on
Water is drawn off, system pressure drops slowly as the water being drawn off is supplied from the accumulator.
System pressure will continue to drop until the accumulator is empty of water and the pressure drops to 10psi (cut in pressure for pump)
Pump cuts in at 10psi, system pressure rises to a balanced position based on demand and pump delivery capacity. Water continues to be drawn off at the tap.
Turn tap off.
Pump continues to run whilst the accumulator refills and the system pressure rises to 25psi at which point the pump will stop - pump cut out pressure.

So you will see a drop in system pressure (as can be seen at the tap) during the time between opening the tap and the pump cutting in. I think increasing the accumulator cushion to a few psi above the cut in pressure will reduce the time it takes the pump to cut in at the reduced pressure . Basically, the accumulator will be empty of water at say 13psi at which time the system pressure will drop very quickly to the pump cut in pressure.

Permanently installing a pressure gauge would be useful in this instance and for future monitoring. If you don’t fancy going the permanent route, a test gauge could possibly be modified to fit on one of the taps. Something like this:
BES.co.uk | Next Day Delivery On 15,000 + Plumbing Supplies

I think you are on the right track, I would suggest the volume of air in the accumulator as you call it is insufficient...possibly.....the volume of compressed air determines the time between on/off. The pump is " hunting"
Some of these accumulators have a membrane which can get damaged and some rely on drain and vent. Also is there a small schrader valve in the top?

 

[JOHNPEET]

I think you are on the right track, I would suggest the volume of air in the accumulator as you call it is insufficient...possibly.....the volume of compressed air determines the time between on/off. The pump is " hunting"
Some of these accumulators have a membrane which can get damaged and some rely on drain and vent. Also is there a small schrader valve in the top?

I’m working on the basis that the system has worked fine in the past! In which case, the capacity of the accumulator will be fine. The pump is certainly “hunting” but not I believe in response to correct system pressures of 10 and 25 psi. - it’s much too fast for these pressures to be attained even if it were without a working accumulator.

 

[billskip]

I’m working on the basis that the system has worked fine in the past! In which case, the capacity of the accumulator will be fine. The pump is certainly “hunting” but not I believe in response to correct system pressures of 10 and 25 psi. - it’s much too fast for these pressures to be attained even if it were without a working accumulator.

Yes agreed, it worked in the past, but things are not equal now, it's 5psi down.
The characteristics of the pump may be delayed the time to achieve the 30 psi with a tap open...so the pump stays on ...how many taps I wonder does he have maybe open all and see if the pump can beat the pressure drop.?

 

[Skylark]

Thank you both, @JOHNPEET & @billskip

Yes, it worked perfectly with a 30 psi cut-off valve but Jabsco would not sell a replacement, I now have fitted a 25 psi cut-off valve. This was recommended by Jabsco.

A couple of issues with the suggested pressure gauge. 1, it is 10 bar FSD and I’m trying to measure pressures between 25 and 10 psi, hence maybe difficult to read with any accuracy. 2. Presumably I’d connect it to one outlet while flowing water through another?

Yes, the accumulator has a car tyre valve at the top and is fairly straightforward to add/remove air.

The boat has 4 hot/cold taps. What do you mean by opening them all to see if the pump can beat the pressure drop?

I really don’t understand why Jabsco supplied a 30psi pump to Beneteau but will not service it.

Would I be better with a 40 psi pump. Would a higher pressure put above design load on the fresh water system, potentially seeking out leaks?

A new pump is an eye watering £250+ but the system now is pretty useless. Not in a million years could one use the shower with the dribble flow prior to the pump kicking in.

Appreciate your help, thanks.

 

[billskip]

Thank you both, @JOHNPEET & @billskip

Yes, it worked perfectly with a 30 psi cut-off valve but Jabsco would not sell a replacement, I now have fitted a 25 psi cut-off valve. This was recommended by Jabsco.

A couple of issues with the suggested pressure gauge. 1, it is 10 bar FSD and I’m trying to measure pressures between 25 and 10 psi, hence maybe difficult to read with any accuracy. 2. Presumably I’d connect it to one outlet while flowing water through another?

Yes, the accumulator has a car tyre valve at the top and is fairly straightforward to add/remove air.

The boat has 4 hot/cold taps. What do you mean by opening them all to see if the pump can beat the pressure drop?

I really don’t understand why Jabsco supplied a 30psi pump to Beneteau but will not service it.

Would I be better with a 40 psi pump. Would a higher pressure put above design load on the fresh water system, potentially seeking out leaks?

A new pump is an eye watering £250+ but the system now is pretty useless. Not in a million years could one use the shower with the dribble flow prior to the pump kicking in.

Appreciate your help, thanks.

Ok first is there a sticker or plate on the pump saying the "head" or pressure eg psi or kg/ cm.. I would not advise a new higher pressure pump...the car tyre valve indicates there is a membrane (normally with the pump off and no water pressure this car tyre valve can be pumped up to 5psi) bicycle pump car tyre pressure gauge.
When I say turn on all taps it is to determine whether the pump remains on or still hunts on and off.
I fully understand you problem re the shower.

 

[JOHNPEET]

Thank you both, @JOHNPEET & @billskip

Yes, it worked perfectly with a 30 psi cut-off valve but Jabsco would not sell a replacement, I now have fitted a 25 psi cut-off valve. This was recommended by Jabsco.

A couple of issues with the suggested pressure gauge. 1, it is 10 bar FSD and I’m trying to measure pressures between 25 and 10 psi, hence maybe difficult to read with any accuracy. 2. Presumably I’d connect it to one outlet while flowing water through another?

Yes, the accumulator has a car tyre valve at the top and is fairly straightforward to add/remove air.

The boat has 4 hot/cold taps. What do you mean by opening them all to see if the pump can beat the pressure drop?

I really don’t understand why Jabsco supplied a 30psi pump to Beneteau but will not service it.

Would I be better with a 40 psi pump. Would a higher pressure put above design load on the fresh water system, potentially seeking out leaks?

A new pump is an eye watering £250+ but the system now is pretty useless. Not in a million years could one use the shower with the dribble flow prior to the pump kicking in.

Appreciate your help, thanks.

Yes, I did notice the FSD of that particular gauge was a bit on the high side, but I did say - “something like this”, just to give you an indication of what could be used. A further google may bring up something more appropriate. Yes, fit it on one of the outlets whilst drawing water from a different one.
Really need the gauge fitted so you can see what the pressures are when the pump operates.

This one’s a bit better, although more expensive. It’s a push fit onto 15mm tube

Basic Dry Test Kit

 

[Plum]

I'm still having fresh water flow problems since replacing the failed pump regulator valve. It seems impossible for the man-in-the-street to contact Jabsco directly but the parts supplier has been helpful and Vyv has been super-helpful by PMs but I'm running out of ideas, hence looking for a fresh pair of eyes.

My Beneteau has a Jabsco fresh water system and the Par Max 4 pump is fitted with a 30 psi cut off valve. It is not possibly to get a replacement cut off valve as these are dedicated to the Beneteau system (seems a bizzare response) so I was supplied with a 25 psi valve as a replacement. The lower pressure valve for this pump is 10 psi and the accumulator should be set at 2-3 psi lower than this, according to the spec and instructions.

View attachment 184020

With the accumulator set to 7-8 psi, per the spec, with any tap fully open, the pump runs for approx 1 second, off approx 2 seconds. But, big but, by the time that the pump cuts in, the flow out of the tap is barely more than a dribble. If I completely vent the accumulator, the pump runs for about 1/2 second, then off for 1/2 second, repeat. The flow is no more than a dribble before the pump kicks in again.

I've video'd this and sent it to the (well known and respected) parts supplier. In turn, they have sent it to Jabsco who have now said "set the accumulator to 13 psi. This contradicts their spec sheet for the 25 psi valve but I'll try it when I next visit the boat.

Does anyone with fresh eyes recognise these symptoms and know how to restore proper (prior to the valve failing) pressure and flow?

Many thanks.

Been following this, very frustrating for you. A thought, are you setting the accumulator pressure with the pump off and a tap open?

 

[Boater Sam]

To set the accumulator air pressure without a pressure gauge try this proven method.
With pump off and a tap open, pump up the accumulator to a fair pressure, about what you would feel effort-wise when pumping up a bike tyre.
Close all taps and switch on the pump.
Allow pump to run until pressure switch turns it off.
Very very slowly release the air pressure until the pump just cuts back in.
Done.

 

[Skylark]

Been following this, very frustrating for you. A thought, are you setting the accumulator pressure with the pump off and a tap open?

It’s a 500 mile return road trip to try something, usually to no avail. Indeed it is very frustrating.

Yes, try to set accumulator with pump off and water drained. That said, I’ve tried pumping dynamically, too, but nothing I’ve done seems to improve the final dribble before the pump cuts back in.

 

[vyv_cox]

It’s a 500 mile return road trip to try something, usually to no avail. Indeed it is very frustrating.

Yes, try to set accumulator with pump off and water drained. That said, I’ve tried pumping dynamically, too, but nothing I’ve done seems to improve the final dribble before the pump cuts back in.

Which is why I suggested that the pump cut-in pressure is too low.

 

[VicS]

It’s a 500 mile return road trip to try something, usually to no avail. Indeed it is very frustrating.

Yes, try to set accumulator with pump off and water drained. That said, I’ve tried pumping dynamically, too, but nothing I’ve done seems to improve the final dribble before the pump cuts back in.

I dont believe the accumulator pressure has anything to do with it. The accumulator is there to prevent the pump cycling on and off rapidly and to produce a steady flow . The correct pressure in the accumulator optimises its performance.

10 psi is more than enough to give a good flow. The pressure at the bathroom taps in a house with a tank in the loft and a gravity system is much less,, probably around half.

I agree with Vyv the actual pump cut in pressure seems to be too low, much lower than the 10psi it should be.

The only other explanation I can think of is that there is some sort of pressure reducing device in the system ( eg a spring check valve ) This one, for example has an opening pressure of 0.7 bar and would not be opened 10 psi.

 

[billskip]

The pressure at the bathroom taps in a house with a tank in the loft and a gravity system is much less,, probably around half.

Old rule of thumb was ½psi per foot head so say 8 feet from the tap up to the top level of water in the loft tank would give say 4psi.
The only non return valve in his system should be on suction side of the pump, it may be an integral part of the pump.
These systems usually run continuously with the pump on once activated. The differential pressure switch is to allow a limited reduction in pressure prior to pump excitement.
All was OK before the pressure switch was changed, if the pump is pumping more volume than is demand then it will switch of and " hunt" as is the problem. If the pump head is say 35 psi and the old switch was 30 psi the pump would probably not ever reach the cut off 30psi with the tap open/shower on. however it could reach 25 psi.
But it can reach the cut off 25 psi.

 

[JOHNPEET]

I dont believe the accumulator pressure has anything to do with it. The accumulator is there to prevent the pump cycling on and off rapidly and to produce a steady flow . The correct pressure in the accumulator optimises its performance.

10 psi is more than enough to give a good flow. The pressure at the bathroom taps in a house with a tank in the loft and a gravity system is much less,, probably around half.

I agree with Vyv the actual pump cut in pressure seems to be too low, much lower than the 10psi it should be.

The only other explanation I can think of is that there is some sort of pressure reducing device in the system ( eg a spring check valve ) This one, for example has an opening pressure of 0.7 bar and would not be opened 10 psi.
View attachment 184093

Or the pressure switch controlling the pump is faulty and not operating at the correct pressures. We need a pressure gauge fitted into the system so that we can see exactly what is going on with the pump cut in pressure! The fault finding needs to be logical and scientific, otherwise it’s just guesswork!