Incoming water pressure 5.5bar

[vala]

Had an ASHP survey last week and engineer tested the pressure and flow from the mains.

incoming pressure is 5.5bar so he noted a PRV should be installed.

I'm happy to install one straight after the mains stop cock, however should I install a strainer before the PRV? 

[Conor]

Maybe.

 

Pro: longer PRV life

Con: likely to get clogged and reduce flow over time. Regular cleaning needed.

 

In water networks, strainers cause more issues and cost than they save. Primarily because once they are fitted, they are forgotten about. Hidden. Don't provide a day to day function, and no telemetry giving any idea of condition or functional performance. If you do fit one, set a reminder on your calender to clean it every 6 months.

[John Carroll]

I think most of these PRVs incorporate a strainer which, from what I read, can be almost impossible to remove for cleaning, so maybe install a upstream strainer.

[Nickfromwales]

On 26/07/2026 at 07:38, vala said:

Had an ASHP survey last week and engineer tested the pressure and flow from the mains.

incoming pressure is 5.5bar so he noted a PRV should be installed.

I'm happy to install one straight after the mains stop cock, however should I install a strainer before the PRV? 

Why?  
 

The new UVC will have a PRedV on the control group, therefore all your cold feeds will become balanced at 3bar by default.

 

I’d keep the 5.5 and tee off it for all the WC’s, the washing machine, dishwasher, outside tap (anything significant which just takes a solo cold feed), and then let the PRedV at the UVC do everything else for all the mixing outlets which require balanced supplies. 
 

This is what I am doing atm for a client, with an accumulator on the mains immediately prior to the control group. 

 

Sounds like you found a muppet here tbh, as there’s absolutely zero need to put a PRedV inline immediately before another one?!? . If you do as I suggest above then showers will be as least affected as possible; eg they can take from the full bore mains so these cold feed items won’t then be robbing pressure from the post 3bar side when you least want them to. 

[Nickfromwales]

1 minute ago, John Carroll said:

I think most of these PRVs incorporate a strainer which, from what I read, can be almost impossible to remove for cleaning, so maybe install a upstream strainer.

Standard PRedV on the control group will come with a stainless gauze filter.

 

I always try to put these at eye level and easily accessible so the maintenance is a doddle.

[-rick-]

1 hour ago, Nickfromwales said:

Why?  

 

Is there a water softener?

 

1 hour ago, Nickfromwales said:

I’d keep the 5.5 and tee off it for all the WC’s, the washing machine, dishwasher, outside tap (anything significant which just takes a solo cold feed), and then let the PRedV at the UVC do everything else for all the mixing outlets which require balanced supplies. 

 

Not sure I'd trust modern appliances (or the flexible piping/connections) to be robust (long term) against 5.5 bar. At least check the manual of them.

Edited 8 hours ago by -rick-

[vala]

Thanks for all the replies.

 

@Nickfromwales I'll strike him off the list for our ashp then!

I'll make sure to have it tee'd off before the control group for the ground floor appliances as checked and they can all take in excess of 5.5bar according to their respective manuals. First floor I have a hot and cold water manifold so will leave these as balanced coming off the control group as most are mixers.