Water pump

[Johny London]

My water pump goes off intermittently - I mean, makes a quick burst of pumping noise once in a while (say, every 4 hours?). I usually turn it off at night for this reason.

Is this normal? (I have heard of accumulators but my current set up doesn't have one). Surely pressure is being lost either forward (leak?) or back to the tank?

No leaks anywhere... at the moment. AFAIK

 

Perhaps this is why some of you have accumulators? Forgive my ignorance.

[rusty69]

There was a recent thread on this. Could be water going back through the pumpto the tank, or calorifier pressure relief valve if you have one. Some Jabsco Parmax pumps advise they don't need an accumulator.

[Geo]

My water pump goes off intermittently - I mean, makes a quick burst of pumping noise once in a while (say, every 4 hours?). I usually turn it off at night for this reason.

Is this normal? (I have heard of accumulators but my current set up doesn't have one). Surely pressure is being lost either forward (leak?) or back to the tank?

No leaks anywhere... at the moment. AFAIK

 

Perhaps this is why some of you have accumulators? Forgive my ignorance.

 

Tell us a bit more about your setup, how do you heat the water, How long has it been doing it. Have you checked every joint for dampness, does it ever do it during the day?

Edited November 29, 2016 by Geo

[Slim]

Could also be the water cooling in the calorifier thus reducing in volume. Or as suggested previously water going back through the pump to the tank. You could try turning the supply off at the tank, assuming a suitable valve, but leave the pump on. That might eliminate one possible cause. Mind you, that would require you to get up in the middle of the night if the pump kicks off. Me, I'd live with turning the pump off overnight at least until it gets warmer

[Johny London]

Hi Geo,

 

I've got a Jabsco water pump (the on or off type, would like to replace it with a variable when I get the chance). There is no accumulator, and no filter before the pump - though Jabsco recommend one. The pipe runs down the side of the boat (starboard) passing the kitchen take off point (no sink as yet!) then the bathroom where there is a bath mixer and thermostatic shower mixer (two separate items) then the pipe carries on to the wc where it feeds the Vetus toilet as well as the basin. It carries on around the stern to the calorifier portside in the rear of the cabin - it's the biggest calorifier you can get (80litres?). Obviously then the hot comes back round to all the same places.

 

Leaks, I've had a few, but then again... not anything actually on the pressurised side of things. I had water coming out of the air admittance valve on the tank - when I may have put the cap back on too promptly after filling. Leaks in various parts of the bath waste, but all that's history now anyway.

 

My previous pump used to do this too - until it failed at 3 months old. I blame that on crap in the new tank and no filter before the pump. When I fitted the new pump, it didn't "go off" for a while. The symptom can occur anytime really.

 

So, maybe just in the nature of this particular system? I hired a boat once, and that used to do it to! Just lucky I guess.

[blackrose]

Could also be the water cooling in the calorifier thus reducing in volume. Or as suggested previously water going back through the pump to the tank. You could try turning the supply off at the tank, assuming a suitable valve, but leave the pump on. That might eliminate one possible cause.

I don't see how it would eliminate anything? If you isolate the tank, water can still flow back through a leaking valve in the pump from the pressurised to non-pressurised sides of the system and then at some point the pump will cycle (and that's likely to happen before both sides of the system are at the same pressure). Because the water supply has been isolated if the pump cycles it won't stop cycling. Certainly don't ever leave a boat with the tank isolated and pump left switched on because you might come back to a burned out pump (or worse). Backflow through the pump is a difficult one to diagnose.

 

For the OP's problem I'd start by wanting to know if the pump also cycles when the calorifier is being heated (assuming there is a calorifier) or does it only happen when it's cooling? If it's the former then I'd look at the calorifier PRV as they often scale up and leak. Have a look at where ever it discharges to - be that a skin fitting on the outside of the hull or a pipe to the bilges and see if it's dribbling. If so twist the PRV a few times to try to dislodge any crap. If that doesn't stop the leak then it may be a case of fitting a new PRV which is a simple job on a vertical calorifier.

 

On the other hand if it's not the calorifier cooling or the PRV which is leaking then I'm afraid you have no other option but to go though the entire freshwater system and check all joints for leaks. If you can't find any leaks, only then should you assume backflow through the pump is the cause.

 

Edit: Also check the pump itself for leaks as that's quite common.

Edited November 29, 2016 by blackrose

[rusty69]

I don't see how it would eliminate anything? If you isolate the tank, water can still flow back through a leaking valve in the pump from the pressurised to non-pressurised sides of the system and then at some point the pump will cycle (and that's likely to happen before both sides of the system are at the same pressure). Because the water supply has been isolated if the pump cycles it won't stop cycling. Certainly don't ever leave a boat with the tank isolated and pump left switched on because you might come back to a burned out pump (or worse). Backflow through the pump is a difficult one to diagnose.

 

For the OP's problem I'd start by wanting to know if the pump also cycles when the calorifier is being heated (assuming there is a calorifier) or does it only happen when it's cooling? If it's the former then I'd look at the calorifier PRV as they often scale up and leak. Have a look at where ever it discharges to - be that a skin fitting on the outside of the hull or a pipe to the bilges and see if it's dribbling. If so twist the PRV a few times to try to dislodge any crap. If that doesn't stop the leak then it may be a case of fitting a new PRV which is a simple job on a vertical calorifier.

 

On the other hand if it's not the calorifier cooling or the PRV which is leaking then I'm afraid you have no other option but to go though the entire freshwater system and check all joints for leaks. If you can't find any leaks, only then should you assume backflow through the pump is the cause.

"No leaks anywhere... at the moment. AFAIK"

 

"the calorifier portside in the rear of the cabin - it's the biggest calorifier you can get (80litres?"

[Slim]

I don't see how it would eliminate anything? If you isolate the tank, water can still flow back through a leaking valve in the pump from the pressurised to non-pressurised sides of the system and then at some point the pump will cycle (and that's likely to happen before both sides of the system are at the same pressure). Because the water supply has been isolated if the pump cycles it won't stop cycling. Certainly don't ever leave a boat with the tank isolated and pump left switched on because you might come back to a burned out pump (or worse). Backflow through the pump is a difficult one to diagnose.

 

For the OP's problem I'd start by wanting to know if the pump also cycles when the calorifier is being heated (assuming there is a calorifier) or does it only happen when it's cooling? If it's the former then I'd look at the calorifier PRV as they often scale up and leak. Have a look at where ever it discharges to - be that a skin fitting on the outside of the hull or a pipe to the bilges and see if it's dribbling. If so twist the PRV a few times to try to dislodge any crap. If that doesn't stop the leak then it may be a case of fitting a new PRV which is a simple job on a vertical calorifier.

 

On the other hand if it's not the calorifier cooling or the PRV which is leaking then I'm afraid you have no other option but to go though the entire freshwater system and check all joints for leaks. If you can't find any leaks, only then should you assume backflow through the pump is the cause.

 

Edit: Also check the pump itself for leaks as that's quite common.

 

Blackrose,

 

I may be dense (I wouldn't argue that point) but as I see it and I repeat I may be dense,:-

The whole system is pressured with pump static. At some time the system loses pressure. The lost water (volume) must go somewhere be it back to the tank, reduced volume in the calorifier as a result of cooling or out of the system via a leak. Have I missed something?

 

Regarding leaving the pump on with the water off the OP implied that a quick burst of the pump was waking him/she/them up. If so in reality they would hear it. I accept fully you don't allow a dry pump to run

[Geo]

Hi Geo,

 

I've got a Jabsco water pump (the on or off type, would like to replace it with a variable when I get the chance). There is no accumulator, and no filter before the pump - though Jabsco recommend one. The pipe runs down the side of the boat (starboard) passing the kitchen take off point (no sink as yet!) then the bathroom where there is a bath mixer and thermostatic shower mixer (two separate items) then the pipe carries on to the wc where it feeds the Vetus toilet as well as the basin. It carries on around the stern to the calorifier portside in the rear of the cabin - it's the biggest calorifier you can get (80litres?). Obviously then the hot comes back round to all the same places.

 

Leaks, I've had a few, but then again... not anything actually on the pressurised side of things. I had water coming out of the air admittance valve on the tank - when I may have put the cap back on too promptly after filling. Leaks in various parts of the bath waste, but all that's history now anyway.

 

My previous pump used to do this too - until it failed at 3 months old. I blame that on crap in the new tank and no filter before the pump. When I fitted the new pump, it didn't "go off" for a while. The symptom can occur anytime really.

 

So, maybe just in the nature of this particular system? I hired a boat once, and that used to do it to! Just lucky I guess.

 

OK Johny, many thanks. My thoughts. Lets start at the water inlet to the pump and work our way round with the possibilities ignoring leaks as I am assuming that you seem to have enough knowledge to have checked for them.

 

1. You mention no filter and muck out of the new tank. That suggests there could be muck that could get into the pump and give a leak back to the tank. So two things fit a filter before the pump and strip and clean the pump, washing the parts in clean water only.

 

2. Galley and bathroom, just make sure there are no taps that have even the slightest drip. I doubt they do but check. Turn the taps off and wipe the tap outlets with kitchen roll or even toilet paper, dry the basin etc and lay a piece of kitchen roll under each of the taps where it would catch any drips. leave it for a few hours and check for a damp patch on the kitchen roll. If there is answer found.

 

3. Calorifier. No mention of and expansion tank. If there is not one where does the water go when the water is heated and expands. Probably out of the safety pressure relief valve. They are not designed for that and it is a waste of hot water. Check that the pressure relief valve is not weeping, same as for taps.

 

4. If there is no expansion tank fit one.

 

5. Other possible causes simple the cold weather, as the calorifier cools the pressure in the tank calorifier drops and when it gets below the pressure of the cold water feed the calorifier takes in more water. That reduces the pressure in the cold water supply and when that drops below the pump start up pressure the pump runs, normally a second or so. Now as to whether it is this depends on how you heat the water in the calorifier and how often, but there is no cure. It is just part of the normal physics of heating water in an enclosed container and it cooling. Well there is a way of stopping the pump running if it is this fit an accumulator and insulate all the pipework in the boat.

 

6. If you have not checked every pipe joint for weeping check it, hot and cold side. Make sure it is dry and wrap a piece of kitchen roll around the joint leave for a few hour and check for damp.

 

That exhaust my brain for the moment let us know what if anything you find

 

ETA no 6

Edited November 29, 2016 by Geo

[WotEver]

There is no accumulator, and no filter before the pump - though Jabsco recommend one.

 

<snip>

 

My previous pump used to do this too - until it failed at 3 months old. I blame that on crap in the new tank and no filter before the pump. When I fitted the new pump, it didn't "go off" for a while.

Putting those two paragraphs together I'd say the odds are strongly in favour of the fact that a bit of muck has entered the pump, partially blocked the non-return valve, and is allowing the pressure to leak back through the pump.

 

Tony

 

ETA That's why Jabsco recommend a filter - a bit more muck could easily destroy this new pump. A filter is cheaper than a pump.

Edited November 29, 2016 by WotEver

[blackrose]

 

Blackrose,

 

I may be dense (I wouldn't argue that point) but as I see it and I repeat I may be dense,:-

The whole system is pressured with pump static. At some time the system loses pressure. The lost water (volume) must go somewhere be it back to the tank, reduced volume in the calorifier as a result of cooling or out of the system via a leak. Have I missed something?

 

 

Only that I can't see how this:

 

"You could try turning the supply off at the tank, assuming a suitable valve, but leave the pump on. That might eliminate one possible cause."

 

...would really help to eliminate (or diagnose) any potential cause? But perhaps it's me being dense.

Edited November 30, 2016 by blackrose

[Geo]

 

Only that I can't see how this:

 

"You could try turning the supply off at the tank, assuming a suitable valve, but leave the pump on. That might eliminate one possible cause."

 

...would really help to eliminate (or diagnose) any potential cause? But perhaps it's me being dense.

 

No you are not dense just missing that there are two systems joined at a non-return valve (NRV), which will only pass water from the cold to the hot. Thus the pump pressurises both the cold-water side and the hot water to say 1 Atm. The water is heated and the hot water side pressure rises to 2 Atm, the water expands let us say into an expansion vessel the heater is now turned off.

 

Now if NO water is drawn off and the water cools down to exactly the same temperature that it was before being heated the pressure of the two systems will be the same. However if someone draws some hot water off, and the pressure in the hot side drops below that of the cold water side the NRV will allow cold water into the hot side to replenish what has been used and the pressure of the two sides is the same and there is still some hot water left in the hot side. Now the water is left to cool, the pressure in the hot side drops as it cools allowing cold water into the hot side via the NRV. The result is cold water side pressure drops pump runs etc etc. May that make sense.

And then I may have misread blackroses post

If the pump is leaking back to the water tank, turning the tank output valve off will gradually stop the pump leak back to the water tank as the pressures of the two sides of the pump equalise. So the pump should stop running intermittently.

Edited November 30, 2016 by Geo

[ditchcrawler]

 

Only that I can't see how this:

 

"You could try turning the supply off at the tank, assuming a suitable valve, but leave the pump on. That might eliminate one possible cause."

 

...would really help to eliminate (or diagnose) any potential cause? But perhaps it's me being dense.

By at the tank do you mean cold storage tank, ie. between the pump suction and the storage tank. Or do you mean the hot water tank ie. calorifer

 

No you are not dense just missing that there are two systems joined at a non-return valve (NRV),

 

Not all boats have non return valves.

[Geo]

By at the tank do you mean cold storage tank, ie. between the pump suction and the storage tank. Or do you mean the hot water tank ie. calorifer

Not all boats have non return valves.

 

Tank = the normal cold tank

 

Well if they have a calorifier which is being heated to 85C or similar that is going to push hot water back into the cold systen when the cold tap is opened until the pressures equalise then drop below the pump turn on pressure. Personally I would not like such a system and I believe most calorifiers made today have an internally fitted non-return-valve. So yes there could be some but I suspect, without sitting down and working it out, the problems would still be similar if not the same.

[WotEver]

You could try turning the supply off at the tank, assuming a suitable valve, but leave the pump on. That might eliminate one possible cause. Mind you, that would require you to get up in the middle of the night if the pump kicks off. Me, I'd live with turning the pump off overnight at least until it gets warmer

As others have said, I don't get this at all. What would it eliminate and how?

[ditchcrawler]

As others have said, I don't get this at all. What would it eliminate and how?

I think he is saying that it would stop water flowing back through the pump to the tank.

[WotEver]

I think he is saying that it would stop water flowing back through the pump to the tank.

Well, I guess it would stop it flowing all the way back into the tank but it would still flow back until the pressure equalised both sides of the pump, surely?

[Geo]

As others have said, I don't get this at all. What would it eliminate and how?

 

 

Well, I guess it would stop it flowing all the way back into the tank but it would still flow back until the pressure equalised both sides of the pump, surely?

 

I think this was dealt with in post #12. Could plagiarism be a foot .

[WotEver]

 

I think this was dealt with in post #12. Could plagiarism be a foot .

I'm sorry, I don't get your point? Who are you plagiarising?

 

ETA - oh, I see that you've edited one of your lengthy posts to make the same point. I completely missed that you'd added yet more.

Edited November 30, 2016 by WotEver

[Geo]

I'm sorry, I don't get your point? Who are you plagiarising?

 

I am not but the quote could well be

[WotEver]

 

I am not but the quote could well be

Yes, reading the thread again (I must admit I only skimmed it) it does indeed appear that the edited extra in post #12 plagiarises post #6.

 

And then I plagiarised it again!

 

Easy to miss points in long posts.

 

Obviously nobody's plagiarising anybody in reality, we've just all come to a similar conclusion.

Edited November 30, 2016 by WotEver

[Johny London]

Thank you everyone for the useful advice - having found no leaks anywhere I'm going to investigate around the calorifier - but I've a feeling it might be muck in the pump again - the last pump only lasted three months and I think this one is starting to get a bit jittery too - the boat builder replaced the pump last time and said they never fit filters before the pump - the pump manufacturer insist one should be fitted.#

I'm afraid I just haven't had time to tackle all the urgent jobs at once.

[Geo]

Thank you everyone for the useful advice - having found no leaks anywhere I'm going to investigate around the calorifier - but I've a feeling it might be muck in the pump again - the last pump only lasted three months and I think this one is starting to get a bit jittery too - the boat builder replaced the pump last time and said they never fit filters before the pump - the pump manufacturer insist one should be fitted.#

I'm afraid I just haven't had time to tackle all the urgent jobs at once.

 

Unfortunately boats are like that always something needs doing. If you don't want to argue with the builder I would buy and fit a filter, strip and clean the pump. Now I don't know what jobs are on the list that would be on my priority list as it could say a pump and its cost.