Water Pump problems? any suggestions please

[Bettie Boo]

Hi all you plumer type folk

 

Here's the issue...

 

Since we've had the boat (2 & 1/2 years), the water pump has come on a few times each day for a few seconds without any taps or anything being turned on. I questioned this when we first moved on board and you kind lads said it wasn't anything to really worry about as it was just regaining lost pressure. Everything was fine till a couple of days ago.

 

I noticed it seemed to be running for longer and longer periods of time, I mentioned this to Dave who assumed I was exaggerating till a couple of days ago when he noticed it himself, the following day it started running much more frequently and for longer. To the point of approx 4 times per hour for up to a little over 1 minute each time. He looked into the cabin bilge inspection hatch and sure enough there was a fair amount of water there and the carpet was wet in one corner of the bedroom.

 

It seems that the pressure relief valve on the calorifier is tripped on permanently and he's checked the value which has a pressure gauge and when the pump is switched on the pressure raises above the 3 bar limit which trips the relief valve open. The water pump is now operating permanently unless switched off at the power source, but when turned back on the water pump doesn't come on till we turn on one of the taps then it just keeps running until switched off at the power source. Dave's assuming now that it's the water pump that's at fault, it's not switching off, driving the water pressure up above the 3 bar limit. It's a SHURFLO pump 3901-0213 he can't find any manuals either in the "boat book of manuals" that came with the boat nor online. The pump is rated at 2 bar but seems to be pushing the water pressure above 3 bar tripping the relieve valve because of it continually running. He can't find any obvious means of adjusting the water pump output pressure to keep it below the 3 bar relieve bar pressure and he's heard that this can be a common problem due to a micro switch failure. Does this sound right to you guys? Should we be looking at a replacement or a service kit?

 

The leak into the bilge has been traced back to a leak on the out put side of the relief valve which has been repaired.

 

Help please - the dishes are piling up and the loo needs to be flushed

[Martin Megson]

Here's a link to the spec sheet for that pump - hope it helps.

 

http://www.hydromarket.fi/files/PDF/70-S3901-0203-3901-0213.pdf

[Bettie Boo]

Hi Martin,

 

Thanks for the link - that's way more than I was able to find online.

Edited June 24, 2016 by Bettie Boo

[bizzard]

The calorifiers pressure relief valve should have its overflow pipe leading overboard, not just overflowing into the boat.

That water pump has an adjustment on the back of its faired in cut out switch. On the end and between where the two inlet and outlet water pipes are is the switch. 5 crosshead screws on it. The screw in the centre of these is the adjustment screw.

[Bettie Boo]

The calorifiers pressure relief valve should have its overflow pipe leading overboard, not just overflowing into the boat.

That water pump has an adjustment on the back of its faired in cut out switch. On the end and between where the two inlet and outlet water pipes are is the switch. 5 crosshead screws on it. The screw in the centre of these is the adjustment screw.

 

Bizzard - Your a STAR!! Dave thought that was what he was meant to be turning based on the diagram / info sheet that Martain supplied but wasn't 100%, thanks for confirming. He's turned it as far as it will go in one direction and nothing has changed so he'll now try it in the other direction.

 

Our calorifier pressure relief valve does have the overflow pipe leading overboard, but it was something to do with the plumbing being set up incorrectly and/or there was a leak between the relief valve and the outside. Dave's fixed that part already

 

Nope - he's turned the adjustment screw as far as it will go in both directions and no change. The pump just runs continuously

 

Any suggestions?

Edited June 24, 2016 by Bettie Boo

[bizzard]

 

Bizzard - Your a STAR!! Dave thought that was what he was meant to be turning based on the diagram / info sheet that Martain supplied but wasn't 100%, thanks for confirming. He's turned it as far as it will go in one direction and nothing has changed so he'll now try it in the other direction.

 

Our calorifier pressure relief valve does have the overflow pipe leading overboard, but it was something to do with the plumbing being set up incorrectly and/or there was a leak between the relief valve and the outside. Dave's fixed that part already

You should really have counted the turns on the screw so that it can be set back to its factory setting, but still not to worry. If the screw doesn't do anything the switch may need to come off by removing the four other screws to clean the little diaphram inside, if still no good, renew the switch.

[Bettie Boo]

You should really have counted the turns on the screw so that it can be set back to its factory setting, but still not to worry. If the screw doesn't do anything the switch may need to come off by removing the four other screws to clean the little diaphram inside, if still no good, renew the switch.

 

Thanks again bizzard, I think he's given up for tonight, he'll be home tomorrow early afternoon, so will take it apart then and do as you've suggested above.

 

Ta

 

B~

[bizzard]

 

Thanks again bizzard, I think he's given up for tonight, he'll be home tomorrow early afternoon, so will take it apart then and do as you've suggested above.

 

Ta

 

B~

Also, I expect Dave has already done it. The calorifiers PRV probably has the red knob specially on it to pull up and twiddle about to clean the valve seatings which is often the reason for them popping off and overflowing. I've found that once they do this they're days are numbered and will need renewing in the near future, about £7.

[ditchcrawler]

There is a tiny hole in some pumps that allows the water pressure onto the diaphragm, this sometimes get blocked up so the diaphragm doesn't see the pressure rise

[bizzard]

There is a tiny hole in some pumps that allows the water pressure onto the diaphragm, this sometimes get blocked up so the diaphragm doesn't see the pressure rise

That's it, behind the cut out switch.

[Bettie Boo]

Also, I expect Dave has already done it. The calorifiers PRV probably has the red knob specially on it to pull up and twiddle about to clean the valve seatings which is often the reason for them popping off and overflowing. I've found that once they do this they're days are numbered and will need renewing in the near future, about £7.

 

Yup, he's done that bizzard, but thanks for the heads up about it being a sign of an upcoming renewal. Will get that part as soon as we are near a chandlers or plumbing shop.

There is a tiny hole in some pumps that allows the water pressure onto the diaphragm, this sometimes get blocked up so the diaphragm doesn't see the pressure rise

 

 

That's it, behind the cut out switch.

 

Thanks both, I've read him the above posts and he'll have a look at it tomorrow when he gets home (fingers crossed that will fix it)

 

Ta for the help - I'll let you know how he gets on tomorrow afternoon

 

B~

[Iain_S]

The "tiny hole" is a likely cause, as is a failed microswitch on the pressure switch.

 

Do you have an accumulator in the system? I had a case where an accumulator wasn't fitted, and the pump would overshoot its cut out pressure, opening the PRV, which would let out a jet of water, reducing the system pressure, and allowing the pump to start again, with the same result.

[Bettie Boo]

Hi Guys,

 

Firstly thank you all for your imput and advice, and the fact sheet.

 

Dave came home today took the pump apart, or at least took out the diaphrame and cleaned off what looked like a wet layer of lime scale build up on the back of diaphragm with some Q-tips, put everything back together and VOULA it works perfect, (and much quieter than before as well).

 

Again, thank you all.

 

Saved us the cost of buying a new water pump

 

.