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moiuk

Water pump every 10mins and full bilge

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My water pump has been operating every 10 mins or so even when no taps are on.  Can't find any obvious leaks and the leaky kitchen tap is just a drip so not that. 

 

Took a closer look in the stern bilge and far too much water there. Put a bowl under the stern gland and water not coming from there.  Tucked up behind the engine though there is the hot water flow and return from the engine to the calorifier and another outlet hole which is pushing out hot water.

 

So, it looks like hot water is coming out of the calorifier and into my bilge (and a lot of it).  

 

Any great ideas for what is causing this?

 

Thanks.

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Could be the pressure relief valve stuck in the open position. It will be on the output of the calorifier and will have a red knob on the end that turns to clear scale. Give it a few turns and it may clear.

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3 minutes ago, mrsmelly said:

Is the prv valve being triggered or failing?

I turned it to see if it was working, and it made a gushing noise for water flowing through it. But can't tell if water is coming out of there. Guess it has to be if there is only one flow into the bilge from the calorifier?

Edited by moiuk

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3 minutes ago, moiuk said:

I turned it to see if it was working, and it made a gushing noise for water flowing through it. But can't tell if water is coming out of there. Guess it has to be if there is only one flow into the bilge from the calorifier?

Can you not see it? is it obscured? Its usualy the culprit but may not be faulty, your water system may be over pressurising due to a fault in the Pump?? Easy enough and cheap to change though if you can get at it?

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3 minutes ago, mrsmelly said:

Can you not see it? is it obscured? Its usualy the culprit but may not be faulty, your water system may be over pressurising due to a fault in the Pump?? Easy enough and cheap to change though if you can get at it?

It's under the bed with easy access.

 

The water pump looks newish as well. Could they have installed a water pump that is a higher pressure than the one they replaced? Or is there a way to check the correct pressure to see if it's the water pump overpressurising or a faulty prv?

Edited by moiuk

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1 minute ago, moiuk said:

It's under the bed with easy access.

 

The water pump looks newish as well. Could they have installed a water pump that is a higher pressure than the one they replaced? Or isn there a way to check the correct pressure to see if it's the water pump overpressurising or a faulty prv?

Yes they could have installed the wrong pump. What does it say on the pump? Is there an accumulater anywhere? Is there a seperate or integral pressure valve on the water pump?

Dont be tempted to by pass the tanks prv or you could burst the cauliflower.

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4 minutes ago, mrsmelly said:

Yes they could have installed the wrong pump. What does it say on the pump? Is there an accumulater anywhere? Is there a seperate or integral pressure valve on the water pump?

Yes there is an accumulator next to the water pump.

 

I will check if the pump has any labelling and if it has its own pressure valve.

 

Is there a standard setting for the prv at which it releases pressure ?

 

 

Edited by moiuk

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1 minute ago, moiuk said:

Yes there is an accumulator next to the water pump.

I am no expert but have lived on many boats. If it were me I would find out what pump type and pressure is fitted. Some will deffo over power the prv on the cauliflower if it is higher than it should be. It is possible to bugger a cauliflower, dont ask me how I know this to be a fact. Is it a shurflo, whale or jabsco par max type pump?

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It sounds to me as if the water is getting passed the prv ( the knob you turned to get the water whooshing noise). The overflow pipe from this connection will come out of the t section of the pipe and almost always empty into the bulge area. Look in your engine  area for a plastic hose type pipe that has no other connecting points attached. Lift it out of the standing water and see if it is dripping, give it a couple of minutes if you've raised it up a bit.

If water comes out of it, that's your cause the "prv", dont worry it can easily be changed. But before you change it try lifting the valve a good 5 or 6 times and let the rubber washer try to reseat itself by closing the valve again. You do get limescale/ crud build up under the washer seat of the valve which causes the symptoms you have. I would recommend doing this anyway every 3 or 4 months to make sure it seals well in the future. Make it part of your routine maintenance is a good idea.

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When did it start doing this? After a new pump was fitted?

Pressure on most common pumps like shurflo is adjustable by the screw in the end.

Check accumulator has about half the pump rated pressure inside when pump off and a tap open.  pump up with a bike pump on the valve in the end (maybe under the cap)

 

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Before doing that, (assuming accumulator is working), stick a tyre pressure gauge on it to establish pump cut out pressure . This can be perilously close to PRV opening pressure. (Which should be printed on the PRV)

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46 minutes ago, mrsmelly said:

I am no expert but have lived on many boats. If it were me I would find out what pump type and pressure is fitted. Some will deffo over power the prv on the cauliflower if it is higher than it should be. It is possible to bugger a cauliflower, dont ask me how I know this to be a fact. Is it a shurflo, whale or jabsco par max type pump?

This is the water pump.

20190618_203752.jpg

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13 minutes ago, moiuk said:

This is the water pump.

20190618_203752.jpg

Looks like its mounted with the adjusting screw pointing down into the plastic container? The pump size is fine for your purpose. Can u get to the adjusting screw and drop the cut out pressure a little?

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25 minutes ago, mrsmelly said:

Looks like its mounted with the adjusting screw pointing down into the plastic container? The pump size is fine for your purpose. Can u get to the adjusting screw and drop the cut out pressure a little?

Not easy to get to it. I'll look up where the screw is online and see if I can find a way of getting to it.

 

I have turned the water pump on whilst watching the outlet in the bilge, and it starts to seep just as the water pump gets up to its cutout.

 

Seems that it's either a faulty prv or the water pump cut out is too high.  Any other possibilities?

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Prv should be 43psi

 

Water pump should be 30psi ish.

 

Not sure adjusting the water pump is going to make much difference?  

 

It's looking like a faulty prv ?

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So, the pump is 2 bar and the prv is 3 bar .

Where does the white pipe out of the prv go?

If the pipe leads into bilge is thre any water coming ot of it?

If yes then it,s the prv. 

If no then you've got a leak.

If it,s the prv try rotating it , twist the red cap, afew times. It may clear the problem . If not replace it.

If it isn't the prv the fun starts finding the leak 

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8 minutes ago, moiuk said:

Prv should be 43psi

 

Water pump should be 30psi ish.

 

Not sure adjusting the water pump is going to make much difference?  

 

It's looking like a faulty prv ?

Yep, its prob the prv. Thats easy to get at, they are very cheap so just change it and see how you go.

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24 minutes ago, mrsmelly said:

Yep, its prob the prv. Thats easy to get at, they are very cheap so just change it and see how you go.

Anything I need to know about changing it?

 

Do I need to empty the tank?  I assume I need to make sure the pressure is released from the system at least ?

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36 minutes ago, moiuk said:

Anything I need to know about changing it?

 

Do I need to empty the tank?  I assume I need to make sure the pressure is released from the system at least ?

We had a prv that continually dripped,  fortunately it was piped to a skin fitting. No amount of twiddling the red knob fixed it. Replaced with new, the old one did have a scoured brass seat. The drip though was then  replaced by a gush every time a tap was opened. I thought I was in for a new pump especially as when I was in a chandlers some one was buying a new flo jet pump because his new shur flo  was exhibiting exactly the same symptoms. Fortunately an ABC mechanic showed me the unmarked and undocumented pressure adjustment screw on the end of the pump. Turn it one way the gush was continuous, the other, the bursts disappeared and the new prv was tight. Every thing was still working four years later.

Lessons:

PRVs have a life. 

The release pressure of PRVs is fixed, but is not precisely it's rated release pressure,, our new one was softer then the original. Once installed though it maintained it's set pressure.

The pump may need it's operating pressure readjusting to match the new prv. Once you have found the adjusting screw under the pump end cap it is not difficult.

This is a lot cheaper then buying a new pump, and hoping the new pump is adjusted to match the prv pressure.

Piping the PRV to a skin fitting is desirable because it is visable, when it showed signs of a runny nose time to tweak it's red knob.

 

Edited by DandV
  • Greenie 1

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8 hours ago, moiuk said:

This is the water pump.

20190618_203752.jpg

Who fits a water pump directly to rigid pipe?

 

Rank amateurs...

Edited by blackrose

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6 hours ago, moiuk said:

Anything I need to know about changing it?

 

Do I need to empty the tank?  I assume I need to make sure the pressure is released from the system at least ?

Switch off the pump. Open a couple of taps. Empty a bit of water out the calorifier. Have an old towel handy. Unscrew the existing prv. Get yourself a roll of gas PTFE tape in the yellow pack (about 50p from screwfix or toolstation). Wrap a bit of PTFE up the thread of your new prv and install. Before messing about with the pump pressure set your accumulator to a few psi below the pump's cut in pressure with a tyre pressure gauge and a bike pump if required. I think 30 psi is your pump's cut out pressure and the cut in pressure would be about 25 psi, so set the accumulator to say 15 -18psi.

 

Make sure you've got everything back together, close the taps and switch the pump back on. If the new prv hasn't sorted out the problem then reduce the pump pressure with the adjustment screw on the head of the pump. If you reduce pump pressure significantly you might then need to reduce the accumulator pressure a bit more too (with pump switched off and tap open).

Edited by blackrose
  • Greenie 1

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26 minutes ago, blackrose said:

Who fits a water pump directly to rigid pipe?

 

Amateurs...

It worked on our boat for years without problems. Did have adjacent dog legs on both intake and discharge. Only ever had one minor leak when the pump came unscrewed from the base so the intake connection became misaligned. 

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4 hours ago, blackrose said:

Who fits a water pump directly to rigid pipe?

 

Rank amateurs...

I don't think it is a problem in itself, but it can transmit more noise by the vibration being transmitted through the rigid pipe.

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