Cap internal blow off (prv) and fit on pipe work instead?

[Jones82]

Hi

I'm Gsr by the way and should get around to sending in my card details.

I'm working on a system boiler and central heating system and the prv/vessel has recently failed, I'm finding it difficult to source the prv short notice, I'm thinking of capping the Prv inside the boiler or the existing discharge pipe work then fitting a new one on the return pipe work close to the boiler, I'm already fitting a replacement external expansion vessel and filling loop so perfect time to do it.

The existing internal vessel has split and is undersized.

Thanks

 

[ShaunCorbs]

Sorry to say no no no and you can't cap the boiler one as it's protecting the boiler and the system

 

[Jones82]

If it was a combi then I wouldn’t even think about it, as someone could isolate the heating and run hot water but it’s a system boiler, if you isolate the heating then the boiler wouldn’t work at all. The by pass and vessel are external, why not the prv? Its common practice on heat only boilers?

 

[ShaunCorbs]

Does the boiler have valves if yes then it's still a no

What boiler is it ?

 

[Jones82]

Remeha advanta plus and it has the usual isolators on the flow return and Gas as they enter the boiler. But if you shut these on a system boiler or even a modern heat only boiler then the flow switch won’t allow the boiler to fire ?

 

[ShaunCorbs]

Still doesn't matter what happens if the flow switch sticks etc if it has valves you can prv needs to be in the same place

And no you can't put one / a new one after the old prv

 

[Jones82]

Yes I guess your right it would also be against the manufacturers instructions.

Thanks

 

[tolly]

I thought some manus allowed remote prv as long as you tee the boiler PRV into the return after the iso's.

No idea if remeha allow this though

 

[ShaunCorbs]

I thought some manus allowed remote prv as long as you tee the boiler PRV into the return after the iso's.

No idea if remeha allow this though

This requires the boiler prv to be new tho

Or a manufacturer link kit/ remote kit

 

[firemant]

Can't do link Adobe mobile. But I fitted a Baci system on my own home and was awkward for PRV. Followed their instructions but did not buy their kit. Plumb BLR PRV into return (?) . Fit remote PRV but had to be the highest point IIRC. Can't remember but the instructions are available online

 

[Gasmk1]

it is against gas safety regs as you are altering the design of the boiler

 

[Last Plumber]

If it has isolation valves beneath the Boiler I would say no. You do not want a situation where the boiler can be isolated without any form of relief.
If you permanently removed the isolation valves then it would be safe.

 

[Chalked]

Another problem with h doing it that way, is that the valve would be open and the valves are not designed to hold pressure on the outlet side of the valve.

 

[tolly]

Remeha advanta plus and it has the usual isolators on the flow return and Gas as they enter the boiler. But if you shut these on a system boiler or even a modern heat only boiler then the flow switch won’t allow the boiler to fire ?

Ive never come accross a heat only with isos underneath or on top?

 

[ShaunCorbs]

Ive never come accross a heat only with isos underneath or on top?

System boiler

 

[tolly]

System boiler yes. But he said "modern heat only boiler"

 

[tolly]

I dont call system boilers heat onlys.

 

[ShaunCorbs]

Heat onlys don't have prvs

 

[tolly]

Heat onlys don't have prvs

I know, read the message i quoted bud. He wrote about closing iso's on heat onlys...thats why i said ive never come accross a heat only with iso's. Incase it goes kaboom with no prv.

 

[ShaunCorbs]

I know, read the message i quoted bud. He wrote about closing iso's on heat onlys...thats why i said ive never come accross a heat only with iso's. Incase it goes kaboom with no prv.

40cdi has ISO valves and no prv there out there

 

[tolly]

You sure? Was at a 40cdi conventional last week.

 

[ShaunCorbs]

You sure? Was at a 40cdi conventional last week.

TBH not 100% sure as I installed it 2 years ago

 

[Jones82]

Your right my mistake, modern heat only's I've fitted don't have iso's and now I know why!

 

[Ric2013]

I've worked on a heat-only installation that had restrictive quarter turn isolators on a heat-only boiler. I removed the isolators for obvious reasons.

 

[richard978]

Hi

I'm Gsr by the way and should get around to sending in my card details.

I'm working on a system boiler and central heating system and the prv/vessel has recently failed, I'm finding it difficult to source the prv short notice, I'm thinking of capping the Prv inside the boiler or the existing discharge pipe work then fitting a new one on the return pipe work close to the boiler, I'm already fitting a replacement external expansion vessel and filling loop so perfect time to do it.

The existing internal vessel has split and is undersized.

Thanks

Don't be silly, if you have your CCN1 and CENWAT then you should know why.

The Avanta is actually made by BAXI and the parts are easy to come by. The issue is replacing them as with most expansion vessels changing them is labour intensive and rear flues often obstruct the vessel.

I can tell you the HYDRO blocks on those are evil to change, I did one last year and it had me sweating.

Maybe its time for a new boiler, its probably 10 years old/

 

[dan_the_plumber]

I would say speak to manafacturer. See if they do a specific ‘remote PRV set’. If not then don’t do it 🙂)