Plumbing woes

[denboy]

Morn all having a problem with a brand new prv constantly dripping it only stops when i turn the water pressure down to a trickle and leaks even more when the water heats up suggestions please in fact when turning tap on and off it becomes a jet wash

Edited April 14, 2009 by denboy

[blackrose]

Morn all having a problem with a brand new prv constantly dripping it only stops when i turn the water pressure down to a trickle and leaks even more when the water heats up suggestions please in fact when turning tap on and off it becomes a jet wash

 

Probably a silly question, but have you tried turning the PRV release knob on top? This sometimes dislodges limescale or whatever is causing the leak.

 

I had the same problem and ended up replacing the PRV. Not a difficult job (depending on access).

 

The other thing is, do you have a hot water expansion tank on your system?

[denboy]

Probably a silly question, but have you tried turning the PRV release knob on top? This sometimes dislodges limescale or whatever is causing the leak.

 

I had the same problem and ended up replacing the PRV. Not a difficult job (depending on access).

 

The other thing is, do you have a hot water expansion tank on your system?

yep done the red knob bit brand new prv ,,no expansion tank have never had one fitted just replaced the clarifier as last one went bang faulty prv

[Smelly]

I can probably guess the answers to these questions mate, but I'll ask 'em anyways...

 

Did the valve come with the tank or was it part of a bundle, hence can you depress the system, return to the swindlers with a sweary look and get a new one?

[steelaway]

return to the swindlers with a sweary look and get a new one?

 

 

Definetly!! - and make sure it is one that does not have any holes in the body above the diaphram and the highest pressure (3bar I think)

 

Alex

[denboy]

angry look on face it is tomorrow must be a duff one

[chris w]

Three reasons why PRV's dribble:

 

1. Faulty/sticking PRV

 

2. Faulty water pump (pressure higher than PRV)

 

3. No expansion tank fitted on heating circuit.

 

Chris

[NBMike]

return to the swindlers with a sweary look and get a new one?

 

 

 

Definetly!! - and make sure it is one that does not have any holes in the body above the diaphram and the highest pressure (3bar I think)

 

Alex

6 Bar PRV's are also available

Mike

[denboy]

6 Bar PRV's are also available

Mike

 

excellent were?

[steelaway]

excellent were?

 

 

90 PSI!!!!! Thats air compressor pressure vessel territory.

I would be very worried about my calorifier at that kind of pressure.

 

Alex

[Proper Job]

90 psi is high. But 90 psi hydraulic is not as dangerous as 90 psi pneumatic

 

3 bar/45 psi should be more than enough for boat purposes. At 6 bar, I would expect the cal' will give way before the prv lifts.

 

edited to add:

Don't forget as well, at 6 bar, the boiling point of water (IIRC) is around 160 deg C. I don't know the source of how your water gets hot, but if its say a gas boiler and you had a faulty burner thermostat, that wont be water coming out of your prv

Edited April 15, 2009 by Proper Job

[NBMike]

excellent were?

Aah Yeah! As fitted to unvented storage units (Megaflo)- prob not a good idea on a copper calorifier. Sorry Den - didn't think it through.

[denboy]

Doh

[blackrose]

yep done the red knob bit brand new prv ,,no expansion tank have never had one fitted just replaced the clarifier as last one went bang faulty prv

 

Another good reason to fit an expansion vessel to the hot water system.

 

http://www.screwfix.com/prods/52162/Plumbi...ion-Vessel-8Ltr

 

It should be T-d in either somewhere on the cold water inlet pipe to the calorifier between the non-return valve (assuming you have one) and the calorifier, or on the hot water outlet side of the calorifier. I used a flexible 15mm tap connector for the job.

Edited April 15, 2009 by blackrose

[denboy]

Another good reason to fit an expansion vessel to the hot water system.

 

http://www.screwfix.com/prods/52162/Plumbi...ion-Vessel-8Ltr

 

It should be T-d in either somewhere on the cold water inlet pipe to the calorifier between the non-return valve (assuming you have one) and the calorifier, or on the hot water outlet side of the calorifier. I used a flexible 15mm tap connector for the job.

did you tee into the hotwater outlet ta

[Keeping Up]

You can get way without a hot-water accumulator if you either don't have a non-return valve (I'm beginning to doubt whether you really need one), or else you have your non-return valve fitted on the outlet side of the calorifier (as mine is).

[chris w]

You can get way without a hot-water accumulator if you either don't have a non-return valve (I'm beginning to doubt whether you really need one), or else you have your non-return valve fitted on the outlet side of the calorifier (as mine is).

This is assuming that you have an accumulator and use that to absorb the hot water expansion. The issue here is that a typical accumulator is 2 litres in size and the hot water from a typical 60L calorifier wil expand a little over that amount if heated by the engine. Further, to make the cold water accumulator work properly, its pressure needs to be set just BELOW the pump's cut-in pressure (<20psi typically) whilst an expansion tank on the hot water system needs to be set just ABOVE the pump's cut-out pressure (>30psi) typically.

 

Obviously, if a hot water tap is opened then any expansion pressure in the hot water system is released and an expansion vessel is not needed anyway.

 

Chris

[blackrose]

You can get way without a hot-water accumulator if you either don't have a non-return valve (I'm beginning to doubt whether you really need one), or else you have your non-return valve fitted on the outlet side of the calorifier (as mine is).

 

The trouble with not having a NRV upstream of the calorifier is that you may find you draw warm water from your cold taps (depending on their locations).

 

did you tee into the hotwater outlet ta

Mine is between the NRV and the calorifier

[Keeping Up]

The trouble with not having a NRV upstream of the calorifier is that you may find you draw warm water from your cold taps (depending on their locations).

This has always been the stock answer, but I have come to disbelieve it. The only circumstances under which you could draw any warm water from a cold tap would be if the water pump was turned off AND you opened a cold water tap which was significantly lower than the hot water taps AND at the same time you opened one of the high-level hot water taps to allow air to enter the system. Even then the amount of warm water would be insignificant (just that which was contained in the hot water pipe) unless the cold tap was below the level of the calorifier.

[Tony Brooks]

This has always been the stock answer, but I have come to disbelieve it. The only circumstances under which you could draw any warm water from a cold tap would be if the water pump was turned off AND you opened a cold water tap which was significantly lower than the hot water taps AND at the same time you opened one of the high-level hot water taps to allow air to enter the system. Even then the amount of warm water would be insignificant (just that which was contained in the hot water pipe) unless the cold tap was below the level of the calorifier.

 

I agree, my experience with the NRV between the tank & pump shows no inclination to feed hot water from cold taps. It could if an expansion vessel was used in the hot water circuit, but I simply do not see the need for one. (my PRV is connected across the pump so any expanding water is fed back to the tank.

 

I believe there might be an issue with breeding nasties around the interface between hot & cold water but no-one seems bothered about that with my domestic hot water system.

[blackrose]

That's not been my experience. I was recently helping a friend on his boat and noticed that not only was the cold feed pipe to his calorifier warm, he also had warm water coming out of his cold tap in the bathroom. He has no NRV in his system.

 

Installing a NRV in order to prevent the cold feed pipe heating up and the possibility of drawing warm water out of a cold tap may well be a stock answer, but then it's probably a stock answer for a reason.

 

This guy seems to fit them:

http://www.boatus.com/boattech/casey/16.htm

Edited April 17, 2009 by blackrose

[bottle]

That's not been my experience. I was recently helping a friend on his boat and noticed that not only was the cold feed pipe to his calorifier warm, he also had warm water coming out of his cold tap in the bathroom. He has no NRV in his system.

 

Installing a NRV in order to prevent the cold feed pipe heating up and the possibility of drawing warm water out of a cold tap may well be a stock answer, but then it's probably a stock answer for a reason.

 

This guy seems to fit them:

http://www.boatus.com/boattech/casey/16.htm

 

To be expected, that would be conduction.

 

Also possible if the tap was teed off, very close to where the cold feed connected to the calorifier.

 

 

I get warm water from my bathroom basin (in house) but only when the central heating is on. ........................Pipes run along side each other, touching in places.

[colin stone]

This guy seems to fit them:

http://www.boatus.com/boattech/casey/16.htm

 

He has a check valve, but no obvious expansion vessel, so the PRV is likely to dribble.

 

1. Accumulator + Check valve/NRV + expansion vessel = no dribble.

 

2. Accumulator + No check valve = no dribble.

 

I have 2 and have never had hot/warm water coming back out of cold taps.

[denboy]

ok folks in laws gave me one of these zilmet tanks i think its the right thing from what i can gather on there site its the small 5 ltr one thought s anyone?

http://www.zilmet.com/cataloghi/1hydroproingl_russo.pdf

its a pdf so takes a while to load

Edited April 23, 2009 by denboy

[chris w]

ok folks in laws gave me one of these zilmet tanks i think its the right thing from what i can gather on there site its the small 5 ltr one thought s anyone?

http://www.zilmet.com/cataloghi/1hydroproingl_russo.pdf

its a pdf so takes a while to load

If you have a typical 60 litre calorifier then a 5 litre expansion tank is small. We have done the maths on here before but you really need an 8 litre expansion tank. You need to set the expansion tank pressure just above the cut-out pressure of the water pump (typ > 30psi) in order to maximise the available expansion volume.

 

Chris