Two boiler install:- PRV location. (Pictures)

[harrygashull]

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

 

[ShaunCorbs]

wheres the expansion vessel for the heating? and are you g3 qualified?

 

[harrygashull]

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.)

 

[ShaunCorbs]

wheres the expansion vessel going then? as dont see a tapping by the boiler

 

[Millsy 82]

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.

 

[harrygashull]

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?

 

[harrygashull]

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.

 

[ShaunCorbs]

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

 

[stevetheplumber]

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

 

[harrygashull]

@ShaunCorbs

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

 

[harrygashull]

@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]

@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

 

[harrygashull]

no but you would need to change pipe work as nominally expansion vessel right by the boiler

I know, the expansion will be directly beneath the boilers?

 

[ShaunCorbs]

I know, the expansion will be directly beneath the boilers?

arnt the heating zones going that way?

 

[stevetheplumber]

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

 

[Unregistered]

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.

 

[ShaunCorbs]

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

 

[Unregistered]

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?

 

[Unregistered]

move it to side of boilers

You reckon il be better off taking ch flows over and using standoffs?

then T the expansion just under the right hand side blr?

 

[ShaunCorbs]

 

[harrygashull]

View attachment 24107

do the red lines signify Isolations?

 

[ShaunCorbs]

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 ?

 

[harrygashull]

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 ?

yes, will be easy enough to do.

annoyed I didn't do it in the first place..

 

[Worcester]

Could be the scale of the drawing D1 looks > 600mm

 

[ShaunCorbs]

Could be the scale of the drawing D1 looks > 600mm

it is also d2 looks like 15mm but then he is g3 certified