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Pressure release valve


Timx
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Hi, when running a tap, for long enough to make the water pump , start pumping, as soon as the tap is turned off and then the water pump stops. Water is spurted out of the p r v into the canal for a few seconds. This used to happen occasionally, but now it has started happening every time I turn on the tap for a few seconds. Is there a problem ? I am not very practical minded in DIY so wondered if I need to get someone to look at it for me. Thanks in advance for any advice.

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Its probably the column of moving water hitting the closed tap so the pressure on the PRV rises until l the pressure pulse "bounces£ back down the system. A bit like water hammer. Turning the pump cut out pressure down a little may very well stop it. The pressure adjustment is usually a screw in the non-cylindrical end of the pump.

 

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I will look at the pump as it is fitted behind a screwed in panel at front I have never looked at it, and try to find the screw mentioned thank you. If I left it doing what it’s doing will it cause a problem ?

CA6BD084-FDD7-4AC0-87BA-0809F82DE45A.jpeg

9793BBCC-4FEA-4CE1-AD33-7FB662184E79.jpeg

Does that white header tank ever need some attention ?

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31 minutes ago, Timx said:

I will look at the pump as it is fitted behind a screwed in panel at front I have never looked at it, and try to find the screw mentioned thank you. If I left it doing what it’s doing will it cause a problem ?

CA6BD084-FDD7-4AC0-87BA-0809F82DE45A.jpeg

9793BBCC-4FEA-4CE1-AD33-7FB662184E79.jpeg

Does that white header tank ever need some attention ?

No more than a glance from time to time just to check it has water in it at an appropriate level.

Phil 

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Does the pump stop almost immediately when you shut the tap? It ought to run on for a few seconds to fully recompress the bag of air in the accumulator and will sound like it's working harder as it does. Also, when you turn a tap on, it should run for a bit (maybe half a litre depending on accumulator size) before your pump kicks in. If it doesn't do those things, I'd suggest the accumulator either needs recharging, is pumped up to such a high pressure it may as well be solid, or else it's duff and needs replacing.

You can use a car type pressure gauge to check it - there'll be a schraeder valve (just like on a car tyre) on the opposite end to the pipework. With the pump switched off and a tap open, the pressure should be a bit less than the pump cut out pressure, but just to make things complicated what it says on the pump and the actual cut out pressure is a bit arbitrary!  As a very rough guide, if it's somewhere between 10 and 20 psi it's probably about right - if it's zero or 40 adjust it if you can. I use a car foot pump. That info should get you out of trouble if it's an accumulator pressure issue. If it is, or if you have to replace the accumulator, do a search for how to set your accumulator pressure properly - there'll be plenty to read.

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I can't see any evidence of an accumulator or expansion vessel n the photos so the OP may not have either. We can't just assume he has one.

2 hours ago, Timx said:

I will look at the pump as it is fitted behind a screwed in panel at front I have never looked at it, and try to find the screw mentioned thank you. If I left it doing what it’s doing will it cause a problem ?

 

 

Does that white header tank ever need some attention ?

1. Look all round the boat for a metal thing roughly shaped like a rugby ball or sphere, post a photo and try to tell us where its plumbed into the system.

2. The white tank is usually the central heating header tank so as long a sit has a little water in when cold its fine.

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7 minutes ago, Tony Brooks said:

I can't see any evidence of an accumulator or expansion vessel n the photos so the OP may not have either. We can't just assume he has one.

I take your point Tony, but there's no pump in the photos either! :D  You're right though, it's not a given that there is one.  I suspect there are few fans here of systems without an accumulator however, even if Jabsco say one isn't needed in some of their advertising blurb for their Par Max pumps.

He said his pump was at the front behind a panel so, if he does have an accumulator, it might likely enough be alongside it.  A quick check at the taps will show whether it's working as expected or not before even looking for it though, so I'd start there. 

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1 hour ago, Sea Dog said:

Does the pump stop almost immediately when you shut the tap? It ought to run on for a few seconds to fully recompress the bag of air in the accumulator and will sound like it's working harder as it does. Also, when you turn a tap on, it should run for a bit (maybe half a litre depending on accumulator size) before your pump kicks in. If it doesn't do those things, I'd suggest the accumulator either needs recharging, is pumped up to such a high pressure it may as well be solid, or else it's duff and needs replacing.

You can use a car type pressure gauge to check it - there'll be a schraeder valve (just like on a car tyre) on the opposite end to the pipework. With the pump switched off and a tap open, the pressure should be a bit less than the pump cut out pressure, but just to make things complicated what it says on the pump and the actual cut out pressure is a bit arbitrary!  As a very rough guide, if it's somewhere between 10 and 20 psi it's probably about right - if it's zero or 40 adjust it if you can. I use a car foot pump. That info should get you out of trouble if it's an accumulator pressure issue. If it is, or if you have to replace the accumulator, do a search for how to set your accumulator pressure properly - there'll be plenty to read.

Thank you, yes the pump does stay on for about ten seconds after tap is shut off,and yes the tap does run for a time before the pump kicks in. I will read what you suggest, but looks like I might need to get someone to look at it.

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1 hour ago, Tony Brooks said:

I can't see any evidence of an accumulator or expansion vessel n the photos so the OP may not have either. We can't just assume he has one.

1. Look all round the boat for a metal thing roughly shaped like a rugby ball or sphere, post a photo and try to tell us where its plumbed into the system.

2. The white tank is usually the central heating header tank so as long a sit has a little water in when cold its fine.

Thank you, I will unscrew the panel at front of boat near the tank tomorrow and report back what I find.i know the pump is in there but not looked.

 

43 minutes ago, Sea Dog said:

I take your point Tony, but there's no pump in the photos either! :D  You're right though, it's not a given that there is one.  I suspect there are few fans here of systems without an accumulator however, even if Jabsco say one isn't needed in some of their advertising blurb for their Par Max pumps.

He said his pump was at the front behind a panel so, if he does have an accumulator, it might likely enough be alongside it.  A quick check at the taps will show whether it's working as expected or not before even looking for it though, so I'd start there. 

Everything works as before, just that the prv is working ninety pc of time as well

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1 minute ago, tomsk said:

I'm no expert but is it seating properly?

Thank you, it has been working fine for the two years I have had it, and the prv has always kicked in occasionally, but now it is working most times after the pump runs.

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26 minutes ago, Timx said:

Thank you, it has been working fine for the two years I have had it, and the prv has always kicked in occasionally, but now it is working most times after the pump runs.

Have you tried rotating it to clean the seat?

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5 minutes ago, Timx said:

Sorry, you mean the prv, I don't think I can get to it

Hmmm... if it needs replacing then you’ll have to, somehow. Rotating it by hand a few times cleans any accumulated scale off the seat (or at least it’s supposed to) which might minimise its little spurts. 

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9 minutes ago, Tony Brooks said:

I think its the thing with a pressure gauge on it in the top photo.

Ah I see, thank you

22 minutes ago, WotEver said:

Hmmm... if it needs replacing then you’ll have to, somehow. Rotating it by hand a few times cleans any accumulated scale off the seat (or at least it’s supposed to) which might minimise its little spurts. 

Thanks I will have a go

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2 hours ago, Sea Dog said:

Does the pump stop almost immediately when you shut the tap? It ought to run on for a few seconds to fully recompress the bag of air in the accumulator and will sound like it's working harder as it does. Also, when you turn a tap on, it should run for a bit (maybe half a litre depending on accumulator size) before your pump kicks in. If it doesn't do those things, I'd suggest the accumulator either needs recharging, is pumped up to such a high pressure it may as well be solid, or else it's duff and needs replacing.

You can use a car type pressure gauge to check it - there'll be a schraeder valve (just like on a car tyre) on the opposite end to the pipework. With the pump switched off and a tap open, the pressure should be a bit less than the pump cut out pressure, but just to make things complicated what it says on the pump and the actual cut out pressure is a bit arbitrary!  As a very rough guide, if it's somewhere between 10 and 20 psi it's probably about right - if it's zero or 40 adjust it if you can. I use a car foot pump. That info should get you out of trouble if it's an accumulator pressure issue. If it is, or if you have to replace the accumulator, do a search for how to set your accumulator pressure properly - there'll be plenty to read.

38569B1D-D865-4DB9-B693-0DF0FF6C0572.jpeg

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1 minute ago, Timx said:

Yeah I twisted it round and released pressure, which has same effect as when pump stops, it raises to over the red 3 on gauge, spits out water then goes down to as shown

Then I’d suggest the same as previous replies, the cut out pressure for your pump is too high. 

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5 minutes ago, WotEver said:

Then I’d suggest the same as previous replies, the cut out pressure for your pump is too high. 

Thanks, I will look at pump mane' and report back. Thanks for replies

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On 09/02/2018 at 18:49, Timx said:

Thank you, it has been working fine for the two years I have had it, and the prv has always kicked in occasionally, but now it is working most times after the pump runs.

 

The PRV is a safety device designed to operate only during a fault condition. This needs fixing.

Worst case scenario is your calorifier will split from repeated over-pressuring and you'll have a £600 repair bill.

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1 minute ago, Mike the Boilerman said:

 

The PRV is a safety device designed to operate only during a fault condition. This needs fixing.

Worst case scenario is your calorifier will split from repeated over-pressuring and you'll have a £600 repair bill.

Thank you, I will look at pump tomorrow, and if twisting the little screw advised does not help I will take it to a boat yard asap 

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