Water pump accumulator issue

[Karl]

I found a leek on one of the O rings on the Jabasco water pump and found when releasing one of the connections on the pump a rush of pressurised water leading to the Webasto accumulator. The leaking pump is fixed with new O rings but now when we turn any tap on etc there is a slight trickle of water and a few seconds delay before pump kicks in. Is this because we have lost air in the Webasto accumulator ? I have tried to add air via the valve with a foot pump but it appears already full of air as I can get any pressure on foot pump unless I did it with great force which I don’t want to do. If I turn tap on and depress foot pump the pressure is released through the foot pump. Am I doing something wrong ?

[Chewbacka]

Why do you call it a Webasto accumulator?  Is it fitted to the cold water system, or to your hearing system?

[Tracy D'arth]

Webasto don't make accumulators.

[Chewbacka]

18 minutes ago, Tracy D'arth said:

Webasto don't make accumulators.

But it could be a pressurised heating system with an expansion tank, and not the cold water system that he his trying to adjust.  So I thought I had better check which tank he is trying to pressurise.

Edited December 9, 2020 by Chewbacka

[Karl]

Sorry, not webasto, Jabasco. Which is connected to cold fresh water tank ! 

 

[Iain_S]

A delay before the water pump starts when a tap is turned on is quite normal when an accumulator is fitted. Just a trickle of water from the tap, however, isn't.

An accumulator, as opposed to the same device being used as an expansion vessel, should ideally be set to pump cut in pressure, usually 15 psi or so isn't far off.

If set above pump cut out pressure, it will do nothing except possibly act as an expansion vessel if there isn't a non return valve on the calorifier.

 

If the pressure switch on the pump gets "lazy", the pump is slow to start and slow to stop, which leads to wide pressure variation in the system. 

 

[Karl]

I have actually found a slight leak from where the body of the pump joins together and will have to replace tomorrow. Would this have anything to do with it. The pump is working but does sound a little different than normal. I suspect the pump is around 11 years old, the same age as the boat. 

[BlueStringPudding]

1 hour ago, Karl said:

I found a leek on one of the O rings on the Jabasco water pump and found when releasing one of the connections on the pump a rush of pressurised water leading to the Webasto accumulator. The leaking pump is fixed with new O rings but now when we turn any tap on etc there is a slight trickle of water and a few seconds delay before pump kicks in. Is this because we have lost air in the Webasto accumulator ? I have tried to add air via the valve with a foot pump but it appears already full of air as I can get any pressure on foot pump unless I did it with great force which I don’t want to do. If I turn tap on and depress foot pump the pressure is released through the foot pump. Am I doing something wrong ?

As I'm currently in on going conversations with Jabsco about water pump problems, I can tell you exactly what they recommend for their accumulator.

 

Firstly, they advise setting the accumulator pressure to 2-3psi below the pump's cut in pressure. Chances are that pressure is probably written on the pump. If not, look up the model of pump on their website which will have a summary of the spec and where you can download a pdf destruction manual if you need it.

Their website also has manuals for their accumulators, explaining how to increase or decrease their pressure. 

 

The important thing when adding pressure to the accumulator is that the pump is switched OFF and a tap is OPEN. (I forgot the latter first time I tinkered with it and nearly died a bike-pump related death ??)

 

Lastly, here's some advice they sent me last week:

 

"Finally what type of pressure gauge do you have for measuring the air pressure in the accumulator tank? Is it one that you can attached to the tank and leave connected?

 

If you do.

 

Switch the pump off and open a tap. Set the air pressure to 5psi and leave the gauge connected.

 

Turn the pump back on and then close the tap (system re pressurised).

 

Next leave a tap open slightly and watch as the pressure drops in the accumulator tank until the pump switches on,

 

Then watch as the pressure increases and the pump switches off.

 

This will give you the exact switch on and off pressure of your pump. You can then use this to set the accumulator tank to 2 – 3 psi below the switch on pressure (again pump off / tap open)."

 

 

[Chewbacka]

30 minutes ago, Karl said:

I have actually found a slight leak from where the body of the pump joins together and will have to replace tomorrow. Would this have anything to do with it. The pump is working but does sound a little different than normal. I suspect the pump is around 11 years old, the same age as the boat. 

A small leak will just result in the pump running for a few seconds every so often as the system pressure drops.   Ideally you know the pump ‘turn-on’ pressure to set it properly.  Turn off the pump, open a tap to release the system pressure then set the accumulator pressure to just below the pump turn-on pressure.  If you don’t don’t know the turn-on pressure, set it to 15psi, and see if it works ok.

[PeterF]

if the accumulator pressure is too high then there will be no water in it, then when the tap is opened there is no reservoir of water to come out until the pump kicks in. If the diaphragm is split then there may actually be no air space in there, so again, there will be no reservoir of water to come out as the tap is opened until the pump kicks in.

[Tony Brooks]

5 minutes ago, PeterF said:

if the accumulator pressure is too high then there will be no water in it, then when the tap is opened there is no reservoir of water to come out until the pump kicks in. If the diaphragm is split then there may actually be no air space in there, so again, there will be no reservoir of water to come out as the tap is opened until the pump kicks in.

But in that scenario the instant a drop of water or air came form the top watever pressure was in the system would  all but instantly drop to zero and the pump shoudl switch on - again all but instantly. that is not what the OP says its doing. He says water trickles for a few seconds before the pump cuts in. That is indicative of a faulty pressure switch in the pump, a well known fault. Its nothing to do with the accumulator working or not.

 

A non-working accumulator would result in far more random instances of the pump running for a few seconds with the taps closed throughout the day, as would a water leak - be it internal to the pump or external.

[Karl]

Thanks for all the info. We have now found the pump is indeed leaking and replaced for a new one of the same but an interesting thing is when I released one of the water connections from the pump the was a lot of water pressure, the one that goes into the accumulator ! I’ve connected it all up o the new pump and is a lot quieter and no leaks. 

       Only problem now is a slight delay before we get a constant flow when we’d turn tap on (a couple of seconds ) and then we get a constant flo. I don’t know wether I am supposed to put air back into accumulator. I have a hand pump with a gauge but when I connect it to the accumulator I can’t get any air into it. It appears rock solid. I also have no idea how much air to put in as don’t know what make the accumulator is. I’m in a right pickle but at least I’ve got a nice quiet water pump which I didn’t have before . Any ideas anyone ?

[Tony Brooks]

2 minutes ago, Karl said:

Thanks for all the info. We have now found the pump is indeed leaking and replaced for a new one of the same but an interesting thing is when I released one of the water connections from the pump the was a lot of water pressure, the one that goes into the accumulator ! I’ve connected it all up o the new pump and is a lot quieter and no leaks. 

       Only problem now is a slight delay before we get a constant flow when we’d turn tap on (a couple of seconds ) and then we get a constant flo. I don’t know wether I am supposed to put air back into accumulator. I have a hand pump with a gauge but when I connect it to the accumulator I can’t get any air into it. It appears rock solid. I also have no idea how much air to put in as don’t know what make the accumulator is. I’m in a right pickle but at least I’ve got a nice quiet water pump which I didn’t have before . Any ideas anyone ?

Tap open, pump turned off.

 

Try to let some air out of the accumulator and if it hisses pump up/release pressure to about half the cut out pressure (that's typically about the cut in pressure.

 

If no air hisses out try pumping up but be aware the bladder may have failed so check again in a few days time.

[BlueStringPudding]

1 hour ago, Karl said:

Thanks for all the info. We have now found the pump is indeed leaking and replaced for a new one of the same but an interesting thing is when I released one of the water connections from the pump the was a lot of water pressure, the one that goes into the accumulator ! I’ve connected it all up o the new pump and is a lot quieter and no leaks. 

       Only problem now is a slight delay before we get a constant flow when we’d turn tap on (a couple of seconds ) and then we get a constant flo. I don’t know wether I am supposed to put air back into accumulator. I have a hand pump with a gauge but when I connect it to the accumulator I can’t get any air into it. It appears rock solid. I also have no idea how much air to put in as don’t know what make the accumulator is. I’m in a right pickle but at least I’ve got a nice quiet water pump which I didn’t have before . Any ideas anyone ?

See my earlier post ( #8 ) for Jabsco's instructions on how to set the accumulator after changing a water pump. Don't forget that you must have the pump switched off (or disconnected if you don't have an isolation switch) and a tap open.