occasional water pump noise

[Grehan]

Usual system, nothing unusual, jabsco, accumulator tank, etc.
In the last few days we've noticed the pump running itself very occasionally, middle of the night, once or twice during the day. Obviously running up to keep the system pressure maintained. Runs for a few seconds only.
Tank's full, taps operate fine (with pump cutting in and out exactly as it should) (hot and cold), hot tank's hot, have looked for leaks, seeping pressure relief valve . . all seems all ok.
Is this normal and just something we haven't noticed before and now we have . . or might there be another explanation?
Any suggestions gratefully received.

 

[alan_d]

There are really only two things that will cause the pressure in the system to drop, activating the pump as you describe. Either you have a small leak that you have not yet identified, or pressure is being lost by water leaking back to the low-pressure (tank) side of the system via a faulty non-return valve. The latter is not uncommon, sometimes caused by grit or other debris stopping the valve from seating properly.

 

[Bilgediver]

Usual system, nothing unusual, jabsco, accumulator tank, etc.
In the last few days we've noticed the pump running itself very occasionally, middle of the night, once or twice during the day. Obviously running up to keep the system pressure maintained. Runs for a few seconds only.
Tank's full, taps operate fine (with pump cutting in and out exactly as it should) (hot and cold), hot tank's hot, have looked for leaks, seeping pressure relief valve . . all seems all ok.
Is this normal and just something we haven't noticed before and now we have . . or might there be another explanation?
Any suggestions gratefully received.

Your accumulator has lost its air charge. You need to get air back into the bladder to stop the pump short cycling . There may be a tyre valve type connection. I expect someone with a system will confirm the pressure but about 1.5 bar might be a good start.

If the pressure does not build up in the accumulator bladder then it may be punctured and a new one required.

 

[VicS]

I dont think he loss of pressure in the accumulator tank alone will not be the cause although it will likely make it run for shorter periods and more frequently.

You must be losing pressure via leak or water is seeping back through the valves in the pump as alan d describes

Investigate the accumulator aspect but if the problem persists and there really are no leaks ... anywhere .. it is time to overhaul the pump or at the very least clean its valves.

 

[vyv_cox]

When this has happened to me a few times I found small blobs of the silicone used to seal the water tank inspection cover had been sucked into the pump and had lodged in one of the valves. The boat came without a pump suction strainer, since rectified.

 

[Steve_N]

Ours tends to run for very short bursts (1-2 secs, every couple of hours) as the water in the calorifier cools. Overnight particularly i.e. when no water is being used so no top up of the pressure.

It never does this when there is no hot water in the calorifier, so I know it's not due to a leak or faulty valves.

Might be what you're experiencing?

 

[mattnj]

Ours tends to run for very short bursts (1-2 secs, every couple of hours) as the water in the calorifier cools. Overnight particularly i.e. when no water is being used so no top up of the pressure.

It never does this when there is no hot water in the calorifier, so I know it's not due to a leak or faulty valves.

Might be what you're experiencing?

that will be the water in calorifier cooling and therefore dropping in pressure, now you said that, it makes sense, ours does it sometimes overnight, but i have just realised, it is only if the calorifier is cooling down. that solves another little mystery, thanks.

 

[jwilson]

Your accumulator has lost its air charge. You need to get air back into the bladder to stop the pump short cycling . There may be a tyre valve type connection. I expect someone with a system will confirm the pressure but about 1.5 bar might be a good start.

Exactly the same thing this year after 4 years no problems: pumped air into the tyre valve on top of the accumulator and stopped the occasional pump running. Difficult bit was getting at the top of the acc tank to fit the tyre pump hose properly - typical modern boat where they fit all the systems and then put furniture on top.

 

[Piddy]

We had this - I changed the accumulator tank and scoured the boat for leaks - eventually gave up and fitted a new pump - problem solved. It appears there was a small hole in the pump diaphragm (as suggested to me by a friend ages ago!).

Not suggesting it is definitely this, just was in our case.

Cheers

 

[fireball]

Ours wouldn't pump up to pressure this season - took the pump head off, cleaned the parts and put it back together ... pumped through the air and hey presto ... all works fine now ... so probably just a bit of debri in the pump.

 

[Grehan]

Thanks for the thoughts folks. Our pump/accumulator is also somewhat buried under the floor . . looks like an awkward but necessary inspection job is called for.

 

[vyv_cox]

If it turns out to be the accumulator here's an easy way to set the optimum pressure. Turn on a tap. Let air out of the accumulator. You will notice that the pump runs more frequently, (unless the accumulator is already empty! ) until eventually it will run continuously. Now pump with the bicycle pump, water pump cycling will reduce but then increase again as pressure rises. Let out some air until pump cycling is at a minimum.

 

[Bilgediver]

I dont think he loss of pressure in the accumulator tank alone will not be the cause although it will likely make it run for shorter periods and more frequently.

You must be losing pressure via leak or water is seeping back through the valves in the pump as alan d describes

Investigate the accumulator aspect but if the problem persists and there really are no leaks ... anywhere .. it is time to overhaul the pump or at the very least clean its valves.

Yes the water pump valves also probably have a minor leak however the system would cycle less frequently if the accumulator was topped up.....I knew there would be lots of suggestions for leaks from the accumulator less peeps

 

[Grehan]

Less peeps?