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Maximum water pressure?

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davebullock

Hi guys,

Can anyone tell me if there is a maximum cold water supply pressure for domestic and / or commercial premises please?

We have an electric water heater below our works kitchen sink which is protected by a 6 Bar PRV.
Having worked for years suddenly the PRV began 'venting to waste' so I checked the type, fitting and pressure marking with a view to replacing it.
It was marked 6 Bar and so I bought a direct replacement and fitted it.
After fitting I immediately noticed that when using the cold water tap on the sink, whenever I closed the tap, the PRV would vent momentarily.
After only one week the valve is venting to waste again. ( and maybe wasting water at night when the demand is low?)
I have actually now tried two new PRV's and both suffer the same problem.
So.....
As I can't find a PRV with a higher rating, and that the heater may have to be limited to 6 Bar can anyone tell me:-

1). Is there a maximum water pressure that the supplier has to abide by?

2). Are City centre (Nottingham) commercial premises supplied at a higher pressure and maybe have some sort of pressure reduction valve (a bit like a gas main regulator) that might have gone faulty?

Expert advice please.
Thanks
Dave
 
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Hi,
Sorry for the confusion it's a Pressure Relief Valve.
I replaced the first one myself as it's not rocket science! Then a 'professional' plumber fitted a second as I thought it might be rocket science after all.
Both failed miserably after a few days so it's just physics like two faulty replacements or incoming pressure too high.
But why has this suddenly changed?
I suspect that there might be a pressure regulating valve somewhere (that might have started to fail) feeding the building as we have had no problems for years. The 'professional plumber' didn't know.
I said surely the pressure should be regulated as it enters the building as there must be a safe working pressure for our heater (hence the 6 Bar PRV being originally fitted?)
The next failure might be the boiler exploding!
If the water can really be up to 10 Bar that's a real worry

Thanks
Dave
 
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It's not rocket science at all.

Lift the phone.

Call in a professional plumber who is qualified in unvented systems and stop pillocking about with it yourself.

UNVENTED WATER HEATERS DO NOT MESS YOU ABOUT! THEY WILL SUDDENLY BITE YOU AND KILL YOU.
 
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Hi Guys
Thanks for the replies.

The pressure relief valve is indicative of another issue. What size is the water heater (in litres)?
Don't think it's a heater issue as even with the heater turned off the Pressure Relief Valve still vents merrily.

It is up to whoever fitted it to do it properly.
Definitely no rocket science involved.
I agree and the plumber was a pukka guy who replaced the second valve and it worked fine for a few days.

If two separate 6 Bar valves from two different manufacturers start to vent then really there is only one issue . ... too much incoming pressure.

What I was after at the start of all this was is there a maximum legal limit that water companies are allowed to supply.
Seems nobody knows if there is one!

Ta,
Dave
 
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Didn't say it was the heater. Did say it was an indication of another issue and asked what size in litres. Pretty simple question, not rocket science to answer.

So far you've replaced two prv's for potentially no reason.

No maximum legal limit, it's upto the homeowner to ensure measures are taken for satisfactory pressure for fittings in house. I had one at over 12 bar.
 
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you need to fit or replace if its already there a pressure reducing valve to the incoming main a pressure relief valve only protects the heater by releasing water where as a reducer drops the pressure in the whole system if it is venting with the heater off then its the incoming preasure thats to high if the water heater is bigger than 15 litres youi need a plumber with an unvented ticket
 
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stevetheplumber said:
you need to fit or replace if its already there a pressure reducing valve to the incoming main a pressure relief valve only protects the heater by releasing water where as a reducer drops the pressure in the whole system if it is venting with the heater off then its the incoming preasure thats to high if the water heater is bigger than 15 litres youi need a plumber with an unvented ticket
Click to expand...
No 15 Litre demarcation now steve (well only for notification), all hot water systems are now covered by Part G & both vented & un-vented not quite sure how it is policed but that is what changed in 2010.
 
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It's not rocket science but I don't have a clue.

I'll call in severn water rather than the plumber with g3 that I have been advised to call.

I'm really in the mood for a thread where the op ignores every bit of advice given because he's decided it's not rocket science.

There's a component missing from your installation. It's not rocket science if you know what you're doing.

You clearly haven't an unvented ticket. Call in someone who has.

Now that's rocket science.....
 
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Thanks for the advice Croppie.
I'll send for a rocket scientist then instead of sarcastic plumbers who think they know it all eh?
Thankyou to all the respondents who offered sensible advice
This thread is now closed.
Dave
 
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When you all come here and dont hear what you want to hear then WE are no good , or we dont know our job or we have been sarcastic .....
Did you ask your self first and took 5min of your time why did you get this sort of response to your questions ?????I am sure you did not .....
 
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davebullock said:
Thanks for the advice Croppie.
I'll send for a rocket scientist then instead of sarcastic plumbers who think they know it all eh?
Thankyou to all the respondents who offered sensible advice
This thread is now closed.
Dave
Click to expand...

You don't have the power.

I do. And I'm not going to.

You come on here, telling us it's not rocket science sorting out the problem yet can't yourself, then when you're given advice you refuse to accept we're being sarcastic?

You deserve everything that's coming to you pal!
 
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Most City centres have fluctuating mains water pressure when measured over 24 hours and 7 days owing to usage. (High population during working days) When large quantities are used the system pressure will be lower in the area (Hydraulic graidiant), however say Saturday evening and Sunday low usage higher pressure. Simple PRV's reduce pressure by a percentage of upstream pressure. On occasions two inline could be used when one will not reduce enough. But they work with washers just like taps so wear and bits of debris are the threat. If you are wasting water from a pressure relief valve and on a meter it could work out costly?
A pressure increase may also be work by utilities replacing leaking mains systems. If it persists perhaps its time to seek an alternative unit that is not reliant on pressure reduction. Good Luck
 
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justlead1 said:
Most City centres have fluctuating mains water pressure when measured over 24 hours and 7 days owing to usage. (High population during working days) When large quantities are used the system pressure will be lower in the area (Hydraulic graidiant), however say Saturday evening and Sunday low usage higher pressure. Simple PRV's reduce pressure by a percentage of upstream pressure. On occasions two inline could be used when one will not reduce enough. But they work with washers just like taps so wear and bits of debris are the threat. If you are wasting water from a pressure relief valve and on a meter it could work out costly?
A pressure increase may also be work by utilities replacing leaking mains systems. If it persists perhaps its time to seek an alternative unit that is not reliant on pressure reduction. Good Luck
Click to expand...

Justlead+1, are you the justlead of long ago?
 
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