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Pressure Reducing Valve ( PRV ) Position


Onoff

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45 minutes ago, PeterW said:

On that last 22-15 reducer, if you use a 22mm compression coupler with a reducing set in it you won't have to do any rework to it when you move up to 22mm throughout ...

 

.....and then leave the 22mm coupler in situ you mean?

 

Or.....how about replacing the solder T where the drain cock is with a 22/15/22 compression T?

Edited by Onoff
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So.....

 

50mm Starrett hole in the corner of the wc:

 

20160824_131844

 

12 then 16 then 25mm 1m SDS thru to until I hit "mud":

 

20160824_132351

 

No way, even with "wiggling" would the 25mm MDPE go through. So BiL's drill with a 32mm bit:

 

20160824_152616

 

A bit of thick wall, st/st, 50mm OD tube, cut at a slight angle, to guard against the tunnel bunnies under the floor:

 

20160824_165123

 

Where it comes in under the footings:

 

20160824_170636

 

20160824_170553

 

And inside:

 

20160824_165250

 

 

 

 

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54 minutes ago, Nickfromwales said:

The jobs yours ;)

 

54 minutes ago, Nickfromwales said:

Note : When you 'call' a tee fitting you say the straight ends first then the centre :)

Eg a tee that sits in 22mm vertically rising pipe work that has a 15mn spur coming out horizontally would be a 22x22x15 tee

Just saying :P:P:P

 

Ta, but don't want the job! xD

 

I found that out about the tee thing at S'fix and had to do a refund / exchange for the difference of 10p when I ordered the wrong compression tee. I noticed that when they gave me the box of bits at the trade counter. Tbh I think I knew but plumb so rarely etc.

 

What I DIDN'T notice until now that they forgot the bib tap back plate to go on the wall outside. Not too late to go and change it but I've had a beer!

 

Where's  best to position all this does the collective think? Below the cistern level or above for easy access / reading of the gauge? Below I reckon.

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On 24/08/2016 at 21:51, Nickfromwales said:

This one?

Does away with exposed pipe work aka no freeze risk ;)

 

Just because there's no exposed pipework shouldn't you still cover the tap in winter with one of those insulated jacket things? I'd obviously sleeve the 15mm copper where it passes thru the wall. Would it be advantageous to run in an over size sleeve and insulate around the pipe?

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Reading the PRV instructions it says:

 

"For residential applications where maximum protection against dirt is required, install a fine filter upstream of the pressure reducing valve".

 

Is this really necessary?

 

(In the words of Arthur Daley, "Stick it on the ta..." xD)

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10 hours ago, Onoff said:

 

Just because there's no exposed pipework shouldn't you still cover the tap in winter with one of those insulated jacket things? I'd obviously sleeve the 15mm copper where it passes thru the wall. Would it be advantageous to run in an over size sleeve and insulate around the pipe?

Drill an 18mm hole and just wrap it with insulation tape. If you make the hole too big you'll stuff yourself when you come to drill and fix it. The fixing holes are quite tight to the pipe so don't take away the brickwork that you'll need to drill, plug and screw into ;)  

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43 minutes ago, Onoff said:

Reading the PRV instructions it says:

 

"For residential applications where maximum protection against dirt is required, install a fine filter upstream of the pressure reducing valve".

 

All the PRV's I've seen ( on the multiblocks ) have had an integral stainless gauze filter. I can't recall if a regular / stand alone PRV has one or not. Do you have the link to your one? If your reading the instructions I assume you've bought one already? 

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  • 4 years later...
On 23/08/2016 at 22:34, Nickfromwales said:

If this is a G3 certifiable UVC install then there's far more to it ;)  

Options are....

1) new install.

2) retro fit. 

 

1)....

Stopcock.

NRV.

Drain-off cock.

NOTE: This is where you should now tee off for the outside tap so it is not affected by the pressure relief valve. Ensure that the outside tap has an integral non-return valve. 

Pipework to UVC location.

Cold feed to multi-block with a local isolation immediately prior to. ( 22mm 1/4 turn lever valve ).

Multi-block located within 500mm of the UVC it serves ( G3 / manufacturer requirement ).

Balanced cold feeds all to be fed from the balanced output of the multi-block ( mixer taps / shower valves / thermostatic devices etc ). 

Therefore no requirement for non-return valves on any mixed feed outlets as all mixers will be at the same potential, regardless of static or dynamic fluctuation. 

 

2)....

Stopcock.

NRV.

Drain-off cock. 

Secondary Pressure Reducing Valve ( in addition to the manufacturer supplied one which has to be mounted at the UVC position as stated above ( so no, you can't nick it and fit it here ;) )). 

Pipework to UVC location.

Cold feed to multi-block with a local isolation immediately prior to. ( 22mm 1/4 turn lever valve ).

All house water pressure is governed by the secondary PRV so the cold feeds can be tapped into anywhere in the house without causing pressure differential issues between hot and cold whatsoever. 

Hot outlet of UVC MUST have a single check non-return valve in line with flow. This is a final failsafe for instances where the secondary PRV fails and mixer taps then can back feed the UVC and over pressurise it to the point of failure. Retro fit only. 

 

Failure to adhere to these particulars is what keeps me in a job ;).

 

 

 

Hi @Nickfromwales

 

I have a similar situation to this comment you made. Our stopcock is in our downstairs toilet next to the utility room, and I'm hoping to get an unvented cylinder installed in our airing cupboard upstairs.

 

I'm planning to run a 22mm feed up the soil pipe boxing, through the loft and back down to the unvented cylinder. Probably in plastic up the soil pipe, and copper across the loft. To save me running an identical feed all the way back to the downstairs toilet and utility room, can I just install a pressure reducing valve right after the stopcock, and tee off my new supply line to the UVC straight away?

 

It would go:

- 25mm main in

- Stopcock

- Pressure reducing valve

- Tee with drain valve

- Tee off to toilet/utility room. We will install a shower in the downstairs toilet, I don't know if this will change anything

- Supply through loft to UVC

- UVC's pressure release valve

- Balanced supply to rest of house (upstairs bathrooms and kitchen)

 

 

I guess it would even be worth sticking a tee before the pressure reducing valve to the outside tap. 

Edited by willmo
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10 minutes ago, willmo said:

 

Hi @Nickfromwales

 

I have a similar situation to this comment you made. Our stopcock is in our downstairs toilet next to the utility room, and I'm hoping to get an unvented cylinder installed in our airing cupboard upstairs.

 

I'm planning to run a 22mm feed up the soil pipe boxing, through the loft and back down to the unvented cylinder. Probably in plastic up the soil pipe, and copper across the loft. To save me running an identical feed all the way back to the downstairs toilet and utility room, can I just install a pressure reducing valve right after the stopcock, and tee off my new supply line to the UVC straight away?

 

It would go:

- 25mm main in

- Stopcock

- Pressure release valve

- Tee off to toilet/utility room. We will install a shower in the downstairs toilet, I don't know if this will change anything

- Supply through loft to UVC

- UVC's pressure release valve

- Balanced supply to rest of house (upstairs bathrooms and kitchen)

Completely new installation, or existing conversion / retro fit onto existing house plumbing? 

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22 hours ago, Nickfromwales said:

Completely new installation, or existing conversion / retro fit onto existing house plumbing? 

 

It's a retrofit in to our existing house with chipboard floors upstairs so I'm trying to keep them down for now. 

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Ok, if retro then scenario 2 for you. With the secondary pressure REDUCING valve at the stopcock location, and the single check NRV on the hot outlet of the UVC you are then fully balanced without using the balanced draw off on the multi block. Chop hot and colds in wherever you like them ?

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33 minutes ago, Nickfromwales said:

Ok, if retro then scenario 2 for you. With the secondary pressure REDUCING valve at the stopcock location, and the single check NRV on the hot outlet of the UVC you are then fully balanced without using the balanced draw off on the multi block. Chop hot and colds in wherever you like them ?

 

Lovely stuff! Thanks @Nickfromwales that's helped settle my mind. I'll set it up like that.

 

26 minutes ago, Onoff said:

As far as I can remember I should have fitted my prv on a horizontal section of pipework according to the manufacturer's instructions...which I never read. 

 

@Onoff very interesting! Thanks for that as I was certainly going to mount it vertically. I'll either change my design or look for one that doesn't have to be horizontal. Surely it can't be due to the very slight pressure difference due to the change in height on a vertical set up

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25 minutes ago, willmo said:

 

@Onoff very interesting! Thanks for that as I was certainly going to mount it vertically. I'll either change my design or look for one that doesn't have to be horizontal. Surely it can't be due to the very slight pressure difference due to the change in height on a vertical set up

 

I half wondered if it was to do with it clogging up. Easy enough to isolate and remove/clean the gauze screen. 

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