Is a PRV needed on combi conversion wtih 6bar mains?

[SarahBee33]

Opinions much appreciated...

We've had a combi conversion done on the 4 bed house we recently moved into. We have had 5 seperate leaks and have a really loud noise in the property that sounds like water being restricted in a specific part of the piping.

The noise is a bit more complex... but we've been told by a few non-plumbers that we should have had a PRV fitted while the system was installed given the mains pressure is 6 bar. The pressure was excessive - turning on the taps even half way made water spray out of the wash basins... (there are now 2 PRVs but this is a bit of a long story... happy to provide more details for anyone interested!).

Our concern is that this may have been a vital part of the install that was overlooked by our plumber and perhaps we could have avoided the leaks and associated damage from this massive mains pressure blasting through a house with old piping and fittings.

So, I'm looking for a consensus from actual plumbers on whether this was just unfortunate or completely avoidable if a standard and vital part of the install - i.e. fitting a PRV - had been properly done. Need to know what is industry standard and if we should be taking this up with the plumber.

Thanks very much.

 

[twgas]

If you mean a pressure reducing valve, I am not aware of any regs saying you should have one.

 

[SarahBee33]

Thank you twgas.

Yes, I mean a pressure reducing valve.

 

[doitall]

Most boilers will state the maximum pressure in the manual, around 3 bar normally so yes you may need one.

Has anyone checked the installers are registered.

 

[hazetimesfive]

6 bar is quite a bit. I would imagine you would get some noises depending on the layout of the plumbing.

which boiler do you now have?

 

[Dan Robinson]

Just one after the main stop cock should be plenty. Probably with a small potable expansion vessel somewhere nearby too.

 

[SarahBee33]

Most boilers will state the maximum pressure in the manual, around 3 bar normally so yes you may need one.

Has anyone checked the installers are registered.

Do you mean gas safe registered? If so yes, also a member of the Chartered Institute of Plumbing and Heating Engineering.

The new boiler is a Worcester Greenstar Highflow 550cdi (floor standing), manual says max mains fed water pressure 10 bar.

I don't imagine there are any specific regulations about this, or that it invalidates the boiler etc, more trying to gauge best practise / accepted standards.

 

[SarahBee33]

6 bar is quite a bit. I would imagine you would get some noises depending on the layout of the plumbing.

which boiler do you now have?

Just posted the boiler details above. The noise is like a jet engine and in just one 10-12ft section of piping upstairs - but only kicks in when kitchen tap downstairs and one bathroom mixer taps are turned on, these are the outlets after this part of the pipe.

 

[doitall]

That answer your question then doesn't it.

6bar is fine so you're down to the install and installer question.

At 6bar pipes need well fixing or they are going to snake all over the place.

Is the 5 leaks on new or existing pipes and what material.

In my opinion 3bar is plenty for most domestic properties.

 

[SarahBee33]

Just one after the main stop cock should be plenty. Probably with a small potable expansion vessel somewhere nearby too.

Thanks Dan,

Several weeks after install they fitted two PRVs in an attempt to address the noise (didn't work). These were installed on the rising cold and rising hot pipes but the cold had already teed off after the mains before the position of the PRV... I've heard and read since that this would render the ineffective??

Do you think this was needed or just a nice to have? - this is the subtle distinction I'm trying to work out.

 

[Dan Robinson]

If its a Worcester it definitely needs one.

Set to around 3 with the aforementioned expansion vessel.

Your installer should have known this. So much for these money grabbing BS organisations!

 

[hazetimesfive]

prv on the rising hot? rising....from the boiler??

wut

 

[SarahBee33]

prv on the rising hot? rising....from the boiler??

wut

I'm kinda quoting what he said so not sure if that's the right way of putting it but yes he put one on a hot pipe - just after it comes out of the boiler before going upstairs... Have had someone who we got in for a second opinion say this is pointless (or maybe it's worse than pointless?) as there should be just one before the boiler and so should not ever be one on a hot pipe... is this right?

 

[hazetimesfive]

its just plain odd...

simply put I would reduce the mains just after the stop cock to 3 bar, with an expansion vessel and be done with it.

by having two separate valves you will end up with unbalanced hot and cold, and this will most likely cause you some problems.

 

[doitall]

The PRV should go on the incoming mains just after the stopcock, and as Dan said a shock absorber just after that.