Jabsco fresh water pump 'blipping'

[Carduelis]

I have a Bene 36 with a Jabsco pressurised fresh water system. The pump is about three seasons old and very little used. My problem is that it switches on momentarily at about 2 minute intervals. At the same time there is a small dribble of water from the foot-pump operated faucet which is connected upstream of the pump. The noise is irritating, especially at night, and I'd like to get it fixed.

I have checked all the upstream pipework very carefully and can't find any leaks. The system doesn't have an accumulator tank.

My thought process is that pressure is somehow leaking back past the pump. If so, would a non-return valve on the inlet side fix the problem?

I'd be very grateful for any thoughts on the subject.

 

[Talulah]

I've never know the pressure to leak back past the pump.
The leak at the foot pump is a clue.
If the foot pump is leaking the electric pump could be filling the tank via the foot pump. Just disconnect it and block of the hoses with a bolt inserted and hose clip and see if that sorts it.

 

[sailorman]

a leaking foot pump causing loss of pressure, the pump is trying to maintain the pressure

 

[VicS]

I have a Bene 36 with a Jabsco pressurised fresh water system. The pump is about three seasons old and very little used. My problem is that it switches on momentarily at about 2 minute intervals. At the same time there is a small dribble of water from the foot-pump operated faucet which is connected upstream of the pump. The noise is irritating, especially at night, and I'd like to get it fixed.

I have checked all the upstream pipework very carefully and can't find any leaks. The system doesn't have an accumulator tank.

My thought process is that pressure is somehow leaking back past the pump. If so, would a non-return valve on the inlet side fix the problem?

I'd be very grateful for any thoughts on the subject.

When you say that the foot pump operated faucet is connected "upstream" you do mean between the tank and the jabsco

Check for leaks downstream of the jabsco, ie between it and the other taps, shower etc.

If no leaks then almost certainly the valves in the pump require cleaning/servicing/or replacing.

If you do not have a filter on the inlet to the pump fit one.

 

[Carduelis]

Thanks for the quick responses.

The foot pump is connected between the tank and the pump. A filter is fitted, and (as I say) there aren't any discernible leaks.

Even if the foot pump valves are leaking, surely this would only result in a small drop in the gravity pressure head. Surely the Jabsco pressure switch operates on the pressurised side..? Actually, even as I write this I'm now wondering - does the Jabsco actually need a pressure head on the inlet side and a tap on the outlet to 'push against' in order for the pressure switch to stay off?

 

[Talulah]

The pump self primes. No head required on the suction side.
On the outlet side the pump pushes against something until the pressure is reached.
It then cuts off.
If the pump is cycling on and off there is a leak in the pressure somewhere.
This can be anywhere downstream of the pump.
If there are no signs of leaks it is possible for the pump to be returning water back to the tank via the manual foot pump should it be leaking internally. (Unlikely.)
You can isolate the problem by closing off sections of pipework. i.e. First remove pipe from pressure vessel inlet and block the end off. Do you still get the problem?

Incidentally. No filter is required on the fresh water system. Filters tend to be used prior to shower pumps.

 

[VicS]

Thanks for the quick responses.

The foot pump is connected between the tank and the pump. A filter is fitted, and (as I say) there aren't any discernible leaks.

Even if the foot pump valves are leaking, surely this would only result in a small drop in the gravity pressure head. Surely the Jabsco pressure switch operates on the pressurised side..? Actually, even as I write this I'm now wondering - does the Jabsco actually need a pressure head on the inlet side and a tap on the outlet to 'push against' in order for the pressure switch to stay off?

I am fairly sure the foot pump is not causing the problem although if its valves were bad perhaps it would be possible for air to be drawn in through it but i dont think that matches the symptoms.

AFAIK the jabsco does not need any positive head pressure on the inlet but would have to check the installation instructions to be sure.
In operation it pressurises the outlet and pipework to the taps. This pressure must be maintained in order for the pressure switch to stay off. Any minute leaks will allow the pressure to fall away and cause the pump to cut in again.

If there really are no leaks then the pressure is escaping backwards through the pump....... hence the suggestion to look at its valves.

The little dribble from the foot pump faucet when the pump cuts in suggests a pressure pulse in the suction pipework ... further evidence IMO that the jabsco valves need attention

Good exploded diags and parts lists on the jabscoshop website btw

 

[Graham_Wright]

You may find this useful;-
http://www.ybw.com/forums/showthread.php?391877-Short-cycling-fresh-water-pump&highlight=cycling.

and this;-
Dear Mr Wright

Our freshwater manual pumps are not designed to be introduced to positive pressure at all. Any pressure exerted on these will either find a leak path or create one.

I hope this helps.

Aiden Devlin
Technical Customer Support
Whale

Main points were fir a filter before the pump and Whale foot pumps do not accept back pressure.

 

[sailorman]

You may find this useful;-
http://www.ybw.com/forums/showthread.php?391877-Short-cycling-fresh-water-pump&highlight=cycling.

and this;-
Dear Mr Wright

Our freshwater manual pumps are not designed to be introduced to positive pressure at all. Any pressure exerted on these will either find a leak path or create one.

I hope this helps.

Aiden Devlin
Technical Customer Support
Whale

Main points were fir a filter before the pump and Whale foot pumps do not accept back pressure.

i have 2 whale foot pumps all fed via the pressure pump these past 16 yrs, i have never had an issue to date.

 

[VicS]

You may find this useful;-
http://www.ybw.com/forums/showthread.php?391877-Short-cycling-fresh-water-pump&highlight=cycling.

and this;-
Dear Mr Wright

Our freshwater manual pumps are not designed to be introduced to positive pressure at all. Any pressure exerted on these will either find a leak path or create one.

I hope this helps.

Aiden Devlin
Technical Customer Support
Whale

Main points were fir a filter before the pump and Whale foot pumps do not accept back pressure.

The problem with the case in your link was that the Whale foot pump was connected in parallel with the electric pump which is not the case with Carduelis' installation. No backpressure is being applied to it

The OP

 

[VicS]

i have 2 whale foot pumps all fed via the pressure pump these past 16 yrs, i have never had an issue to date.

Fed via the pressure pump ... not in parallel with it presumably just in series with it so that they pull water through the pressure pump when used or allow water to flow though them when the pressure pump is used.

Not the same as Carduelis' system or the one in Graham's link

 

[Talulah]

There will be a back pressure to the foot pump unless you have it connected to a separate tap.
On our foot pump the outlet is just T'd into the supply going to the tap. No issues in 10 years.

Actually I'm not sure that's true. There may be a non-return valve between the foot pump and where it is T'd in to the pipe going to the tap.

 

[sailorman]

Fed via the pressure pump ... not in parallel with it presumably just in series with it so that they pull water through the pressure pump when used or allow water to flow though them when the pressure pump is used.

Not the same as Carduelis' system or the one in Graham's link

all water flows through the whale pump whether by foot with the pressure pump off or open the faucet with the pressure pump

 

[Carduelis]

Thanks again folks.

just to clarify the pipework on 'Goldfinch'. The footpump is connected in parallel to the Jabsco and outlets to the sink via an open faucet i.e. not a tap with an on/off. I imagine it is there to enable the crew to get drinking water if the electrics fail. It shouldn't be under any pressure other than a tiny head of gravity from the tank.

When the pump 'blips', we see a dribble of water from the faucet. The sink is higher than the tank so there must be some pressure being generated somehow. My only guess, as per the OP was that somehow the Jabsco was putting a back pressure into the feed. We have been told (above) that this is unlikely so I'm still foxed.

 

[VicS]

Thanks again folks.

just to clarify the pipework on 'Goldfinch'. The footpump is connected in parallel to the Jabsco and outlets to the sink via an open faucet i.e. not a tap with an on/off. I imagine it is there to enable the crew to get drinking water if the electrics fail. It shouldn't be under any pressure other than a tiny head of gravity from the tank.

When the pump 'blips', we see a dribble of water from the faucet. The sink is higher than the tank so there must be some pressure being generated somehow. My only guess, as per the OP was that somehow the Jabsco was putting a back pressure into the feed. We have been told (above) that this is unlikely so I'm still foxed.

The foot pump is not in parallel with the electric pump if it has a separate outlet. They could only be described as in parallel if both were connected to the same outlet.

I am sure that the Jabsco is putting a little pressure pulse into the feed to the foot pump and causing a little dribble because its valves are defective. This is also why it pulses every couple of minutes.

There is either a tiny leak on the prssurised pipework or the pump valves are defective.

The foot pump has nothing to do with it in your case.

 

[Talulah]

The foot pump is not in parallel with the electric pump if it has a separate outlet. They could only be described as in parallel if both were connected to the same outlet.

Our water tank is fitted with two extraction tubes. One for the foot pump and a separate one for the electric pump.
If the foot pump was T'd off from the same supply going to the electric pump and there was an open faucet on the foot pump I could see air getting drawn into the electric pump via the open faucet and through the foot pump.
Does the OP have separate supplies from the tank for the foot and electric pump?

 

[temptress]

Do you have a hot water system or is it all cold water? IMO the dribble from the foot pump shows the foot pump needs attention but I would think it unlikely to be the cause of the pressure loss. The pressure pump pulls water into it from the tank or anything else commented to the low pressure in side.

Incidentally Jabsco recommend you have a coarse filter on the low pressure intake side of the pump.

 

[VicS]

Our water tank is fitted with two extraction tubes. One for the foot pump and a separate one for the electric pump.
If the foot pump was T'd off from the same supply going to the electric pump and there was an open faucet on the foot pump I could see air getting drawn into the electric pump via the open faucet and through the foot pump.
Does the OP have separate supplies from the tank for the foot and electric pump?

He says it is connected upstream of the Jabsco in #1

I mentioned the possibility of air being drawn in via the open faucet and the foot pump in #7 but as I said previously I dont think the symptoms match that scenario.

 

[Graham_Wright]

Do you have a hot water system or is it all cold water? IMO the dribble from the foot pump shows the foot pump needs attention but I would think it unlikely to new the cause of the pressure loss. THE pressure pimp pulls water into it from the tank or anything else commented to the low pressure in side.

Incidentally Jabsco the recommend

Edit?!

 

[Carduelis]

Yes OK, I suppose it's not strictly 'in parallel' although I suppose you could argue that water following either route ends up in the same place - the sink plug ole!

There is a calorifier but it is connected to the pressure side of the Jabsco. It has it's own pressure relief valve into the bilge.

I'm thinking of trying two courses of action:

1. Block off the footpump feed. If the Jabsco is pressurising it's feed then the excess pressure will go back to the tank i.e. no effective difference. If there IS a difference, then the footpump valves must be at fault.

2. Fit a non-return valve immediately prior to the Jabsco.