Help, please - pressurised water system working erratically.

[NealB]

We've owned this boat for about a year now, and the pressurised water system (hot and cold) has worked perfectly....till about a week ago.

The pump (diaphragm type) then suddenly ran continuously in the middle of the night, without any taps open. We switched it off, and went back to sleep.

Next day, it all seemed to work perfectly again, so the problem was ignored.

Since then the problem has recurred several times, and, worse, sometimes now no water is delivered to the taps when we want a cuppa.

If I disconnect the outlet from the pump, there's plenty of water pressure, so the pump seems to be working ok.

Any suggestions on where I should investigate next? Air leaks? Accumulator?

Many thanks for any tips.

 

[No Regrets]

Pump.

The loss of pressure within the pump is activating the 'on' switch, and when the taps are opened for real, it can't pump.

It may just need a clean out!

 

[sailorman]

1/ check the "Charge" pressure in the accumulator with the pump off & water pressure released
2/ it might be a dodgy pressure switch

 

[dockmaster]

If it is the switch you dont have to replace with the expensive origional type go to the plumb center or similar and buy a domestic one for half the price and it will be adjustable.

 

[Phoenix of Hamble]

If your accumulator tank has a schrader (car tyre style) valve in it, try pumping a bit of air in with a bicycle pump or a foot pump, or drain the system and refill it... its possible that there isn't enough 'charge' in the system as Sailorman says....

 

[Bilgediver]

Sounds like you have either a sticking suction or sticking delivery valve on the pump...MAybe some crud stopping the valve closing this will stop the pump pressuring up the system however if you take the hose off the pump may deliver a lower pressure which you think is fine!!!!!

Try stripping and cleaning the pump and dont have the pressure swich set higher than necessary.

 

[PCUK]

If it occasionally doesn't pump the only thing stopping it is the pressure switch. Test by by-passing the switch and switching on and off manually then clean or replace.


Clean or replace.

 

[vyv_cox]

I assume from your original question that when no water emerges from the tap the pump is running? In this case it sounds very much as though the problem is as suggested, that there is debris in the pump valves. I have suffered blobs of silicone sealant stuck in the suction valves, which caused the pump to run almost constantly in its efforts to pressurise the system. When the tap was opened the flow was negligible, as the pump was unable to fill on each stroke of the diaphragm.

If, on the other hand, the pump doesn't run when you open the tap, then the problem lies elsewhere. Could be a bad electrical connection, a fault with the pressure switch (sometimes they become dislodged and just need pushing back in place) or even a motor problem.

 

[NealB]

Hopefully, problem now solved....thanks for your advice.

I stripped the pump down, and couldn't see anything obvious wrong there.

Whilst removing it, however, I noticed that one of the junctions in the cold water out line (feeding to the cold taps) was slightly loose.

Remaking that joint seems, fingers crossed, to have fixed things. The pump now gives a gushing torrent from all taps, and cuts out almost instantly once the taps are closed (before, it had been 'tapering' off).

Anyway, thanks again, and I hope this is the end of this particular little tale for at least a while.

 

[vyv_cox]

Re: Hopefully, problem now solved....thanks for your advice.

Can't see why a slight outlet leak could prevent the pump from delivering, although it might make it run frequently if you don't have an accumulator. Hope you've fixed it.

 

[charles_reed]

Surprised

you didn't see the results in your bilges.

 

[NealB]

Re: Hopefully, problem now solved....thanks for your advice.

Agreed - I couldn't really see a link between a slightly seeping joint and the problem (no different to having a dripping tap, is it?).

However, all still working beautifully now.

Maybe stripping the pump cleared something I hadn't noticed, or perhaps disconnecting, then cleaning and reconnecting the electrics did the trick.

Anyway, fingers crossed!

 

[NealB]

Re: Surprised

There was just the tiniest seepage, barely noticeable, and it was into the same part of the bilge as the traditional stern gland (which drips slightly).

So not that surprising, maybe.

 

[sailorman]

Re: Hopefully, problem now solved....thanks for your advice.

if there is a tank in the system the pump shouldnt come on for a few seconds when a tap is turned on as the reserve pressure should deliver thew water thern when the pressure drops the pump is switched

 

[Bilgediver]

Re: Hopefully, problem now solved....thanks for your advice.

Oh dear......now why didn t we think of a loose connection airlocking the pump......

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