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We have moved onto our boat and things are going well.  This morning when I turned the tap on the water pump came on (as usual) but when I turned it off it kept going but in pulses and won't stop. We turned the pump on and off again and looked at connections to the calorifier and we can't see anything out the ordinary.  Any suggestions on what might be the problem? 

 

Thanks in advance! 

 

edit: it appears to have fixed itself and is no longer pulsing! Not sure what the issue was, any suggestions are welcome 😀

Edited by katie_hannah
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Which pump? What do you mean by "pulses" please?

Does the water system have an accumulator?

If the pump runs/stops/runs /stops yetc. continuously then you either have a duff pressure switch or the accumulator needs pumping 

 

Let the pump run for 20 seconds with all taps shut. Turn the pump off.  Open a tap.  Does the water run for a while (how long?) and then stop or does it only dribble when you open the tap?

 Is the calorifier PRV (thing with a red knob usually) letting out water when the pump is pulsing?

 

N

 

Edited by BEngo
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I am afraid the question is not clear enough to give much practical advice apart from what  BEngo said.

 

I assume that you are talking about turning a tap on and off with the pump turned on all the time.

 

What your symptoms say is that either the pump  is not turning itself off by the pressure switch or, far more likely, you have a leak somewhere. This may not be an external leak, it could be muck holding a valve or two in the pump open so the pressure can leak back through the pump. More likely it is the PRV that is normally close to the calorifier leaking an its outlet may well be overboard or into the engine area bilge so you would not find see anything amiss around the calorifier. This can be caused by two things. Scale on the seat, especially if you have no expansion vessel. This can cure itself as yours seems to have done or you can give the knob a few twists in the hope the scale is flushed off the seat. The other thing is the pump pressure switch sticking closed or maladjusted so the water pressure builds high enough to force the PRV off its seat.

 

I don't think its an accumulator pressure problem because that would show if the pump was turning itself on and off (cycling) only when a tap was open and in any case an accumulator won't stop cycling but will alter its frequency so when you are just filling a kettle it seems as if the cycling has stopped. A pump will also not cycle if its delivery volume is less than the tap can pass so the pressure can not build up.

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Could have been some air in the system which has now found its way out.  I find air can take  a few days use to clear , especially if the boat has been out of use a while.

I had a few issues earlier this year and found the tank breather was partial clogged . Once the breather was cleared the problem was solved.

Edited by MartynG
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On 22/11/2020 at 12:44, ditchcrawler said:

Ill make a guess, the battery volts were low

 

34 minutes ago, MartynG said:

Could have been some air in the system which has now found its way out.  I find air can take  a few days use to clear , especially if the boat has been out of use a while.

I had a few issues earlier this year and found the tank breather was partial clogged . Once the breather was cleared the problem was solved.

 

Surely discharged batteries would slow the pump and prevent it reaching cut out pressure so it would stay running with the taps closed.

 

Air in the system would not prevent the pump reaching cut out pressure but it would take a long time to get there so it may appear that it was running all the time if it was switched off quickly.

 

In neither case do I think either suggestion fits with "but it kept going in pulses". That phrase suggest to me that it was cycling (turning on and off) however the OP has not explained exactly what was meant by that. The phrase suggest some kid of internal or external leak is more likely.

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Further thought re the above post. The one "air in the system" thing that would fit the "but it kept going in pulses" would be if it was nearly out of water so it was alternately sucking air and the water. That way it would never get up to pressure and if another person moved to another position on the boat in the boat the heel so caused may well be enough to put the tank outlet under water again - for a short time.

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I had a fairly similar thing a few months ago.  Emptied the tank deliberately then refilled it.  When I turned the pump on again it ran, took suction  and after a couple of seconds  started on/off pulsing like a mad thing.  Noise was horrendous and the pressure switch and Morco did not sound like they were having a good day at all.

 

Turned pump off, opened the taps, turned pump on, ran some water through the taps, which cleared some air from the pump-to-sink pipe then  turned the taps off.  Pump ran up to pressure normally and switched off. No probs since, including a 6 week autumn excursion.

 

I have a Johnson pump with a separate Schneider Square D pump switch and an accumulator which was correctly pressurised.

 

I still cannot see why it should do what it did. Resonance may come in to it I think, possibly something like  water hammer (as in pressure fluctuations caused by suddenly changing flow conditions) and maybe the additional pipe needed to mount the Square D.

N

 

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4 minutes ago, BEngo said:

I had a fairly similar thing a few months ago.  Emptied the tank deliberately then refilled it.  When I turned the pump on again it ran, took suction  and after a couple of seconds  started on/off pulsing like a mad thing.  Noise was horrendous and the pressure switch and Morco did not sound like they were having a good day at all.

 

Turned pump off, opened the taps, turned pump on, ran some water through the taps, which cleared some air from the pump-to-sink pipe then  turned the taps off.  Pump ran up to pressure normally and switched off. No probs since, including a 6 week autumn excursion.

 

I have a Johnson pump with a separate Schneider Square D pump switch and an accumulator which was correctly pressurised.

 

I still cannot see why it should do what it did. Resonance may come in to it I think, possibly something like  water hammer (as in pressure fluctuations caused by suddenly changing flow conditions) and maybe the additional pipe needed to mount the Square D.

N

 

I agree that in this case its probably probably water hammer but the OP did not mention any extra noise. that is not to say there were none but  remote diagnosis can only be done on the basis of the stated symptoms. Regrettably a number of ordinary boaters don't seem to understand this and omit vital info and then don't give answers when asked.

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Indeed.  It is hard to be helpful without any real information. 

 

The OP's problem has gone away, and it seems we shall not know more.  That means that the forum's collective knowledge will not be increased and a future sufferer will wait longer for a diagnosis.

N

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4 minutes ago, BEngo said:

Indeed.  It is hard to be helpful without any real information. 

 

The OP's problem has gone away, and it seems we shall not know more.  That means that the forum's collective knowledge will not be increased and a future sufferer will wait longer for a diagnosis.

N

 

Or even be given an incorrect diagnosis because vital symptoms were not disclosed.

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Suitable and restrained response to some comments some might have found patronising......

 

We’re about to launch into narrow boating and will have plenty of dumb questions I fear.....will provide lots of detail behind them for certain....

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52 minutes ago, agew said:

 

 

We’re about to launch into narrow boating and will have plenty of dumb questions I fear.....will provide lots of detail behind them for certain....

You can't give too much info on here. Its very rear that faults get better by themselves 

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