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Discuss Two boiler install:- PRV location. (Pictures) in the Plumbing Jobs | The Job-board area at PlumbersForums.net

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harrygashull

Gas Engineer
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Hi,
Iv been installing a two boiler system with tank etc, Im just at the point where the sealed system kit is going in tomorrow. Now the way iv designed it means that if certain isolation valves are turned off then the boilers will be cut off from the PRV.

Now at the back of my head is something telling me that I'm sure that the PRV should no matter what be in a position where it can't be isolated from the heat source (i.e. the two boilers)

The location for the system fill, expansion and prv is going to be the 15mm copper tube at the bottom left just above the skirting board.

Am I being mad or am I right to be concerned.

Id also appreciate any kind feedback as to the design of the system and any improvements you would make. (please be kind)

Thanks !

Pictures are here :-

https://www.************/MCSHeating/photos/pcb.1313937292012781/1313933075346536/?type=3&theater

Picture 2

https://www.************/MCSHeating/photos/pcb.1313937292012781/1313933078679869/?type=3&theater
 
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wheres the expansion vessel for the heating? and are you g3 qualified?
 
As I said, thats all going in tomorrow. And I'm not personally but one of our other lads is and he is coming to commission it when ready (its not connected to mains yet and system is still empty.)
 
wheres the expansion vessel going then? as dont see a tapping by the boiler
 
I'd put expansion next to boiler and as the returns are not isolated separately the pro with that.

Me personally wouldn't of fit wheel head valve you can guarantee next time you use them they won't work, quarter turn valves all the way for me.
 
At the bottom of the first picture, there are 3 gate valves and then a 28mmT reducing down into 15mm which then goes towards the boilers.(along the skirting)

This 15mm was what I was planning on using for the system fill, expansion and to which the prv would also be connected to the system. However if you follow the succession of pipework, the magna clean is isolatable as is both flows from the boilers hence the PRV can be isolated in a way.

Best way would be to T in between the boilers and use that as expansion/prv feed?
 
Iv had trouble with the full bore quarter turn valves leaking in the past though...

I do agree that might be the best way around it, to fit the PRV between the boilers return and magna clean.
 
Iv had trouble with the full bore quarter turn valves leaking in the past though...

I do agree that might be the best way around it, to fit the PRV between the boilers return and magna clean.

not had a one tbh and as you have said t between the two boilers on the return, but really when you were planning it you should of put a t instead of an eblow on the manga
 
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if you want to be able to isolate the boilers seperately your going to need two PV's or some three way valves that dump the water from one port when the boiler is isolated then just one upstream pv
 
@stevetheplumber

Im not that fussed about isolating them separately, as long as they can be both isolated then the boilers have in built drain offs so if work needs to be done then they can be drained easily.

Not sure what you mean about the three ports and PVs?
 
@ShaunCorbs

I know.. kicking myself a bit now, tbf won't be much work to sweat it off and swap it for a T.

no but you would need to change pipe work as nominally expansion vessel right by the boiler
 
on commercial work where there is a number of boiler they some times use a three way valve to isolate the boilers when it is closed from the expansion pipework it automatically drains the boiler leaving an end open
 
arnt the heating zones going that way?

yes- will be reducing down to 22mm and bending to go through the channel I made which the flow passes through to the pump.

should mean that there is enough room for the expansion.

If not then ill move expansion to the side of the boilers.
 
yes- will be reducing down to 22mm and bending to go through the channel I made which the flow passes through to the pump.

should mean that there is enough room for the expansion.

If not then ill move expansion to the side of the boilers.

move it to side of boilers
 
on commercial work where there is a number of boiler they some times use a three way valve to isolate the boilers when it is closed from the expansion pipework it automatically drains the boiler leaving an end open


Oh right, that sounds an interesting method. If the system drains itself then I assume that either an automatic filler or open vented setup is used?

and what happens when the three way valve starts passing?
 
12313653_1313933075346536_303062842697533079_n.jpg
 
do the red lines signify Isolations?

no cuts as the pipework would have to be moved up on the boilers and shortened on the one but the magna

get what i mean ?
 
Could be the scale of the drawing D1 looks > 600mm
 
Thanx, thought it was the scale; Out of interest why did you increase the D2 to 28mm?
 
how did you get on today harry?
 
how did you get on today harry?

Not bad thanks Shaun - not as far as id have liked but hey ho...

managed to get most of it wired up.

condensate is done with the exception of a reducing bung.

expansion, prv and filling link are all in place but need connecting. (I followed your advice about the expansion and I think its paid off.

Tomorrow ill be finishing off the conduit and pipework and hopefully the flues.

Picture from today:

https://www.************/MCSHeating...088078497709/1315035975236246/?type=3&theater
 
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Looking good... I normally drill the flue holes first tho, gonna get it all covered in dust now :p
 
looks ok harry, need a bit of work on the wiring tho (clips) :) but thats me being picky :D
 
Looking good... I normally drill the flue holes first tho, gonna get it all covered in dust now :p

+1 and normally boilers in the way else, unless there going straight up
 
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