Pressure relief valve off CH pipe

[oldbuffer]

If I'm reading the original post correctly, there is a third problem. If you run the flue through an existing chimney opening, and it is 20 feet (say 6 metres) in length, then it will probably have two joins in it. Under current regulations these need to be accessible for inspection

 

[Onetap]

They call the remote pressure valve the "secondary". As is activates first it must be the primary.

FFS! This has to be a wind up.

The manufacturers have got their terminology wrong now, have they?

It is called a secondary device because it is, secondary to and in addition to, the primary PRV which is on the boiler. The boiler PRV discharge is to be piped as per the instructions, to atmosphere. The secondary PRV does not replace the primary PRV.

It seems likely that you want to install your own boiler and are putting up these clueless ideas because you can't see a problem with them. The task is too technical for you, you need to employ a competent installer who will know the reasons for not doing things as you suggest.

 

[Biggles..]

The instructions that came with the last manufacturer remote kit I did told you that the boiler PRV if unsuitable for discharge is to be tee'd into the boiler return.

 

[denso13]

FFS! This has to be a wind up.

It is

JohnHarrison = WaterSystems, DrDrivel, BigBurner, GeorgeBramwell, RichardHansonGranville.

 

[Onetap]

FFS! This has to be a wind up.

It is

JohnHarrison = WaterSystems, DrDrivel, BigBurner, GeorgeBramwell, RichardHansonGranville.

Oh, it's Drivel!

I've been away, I thought he must be dead by now.

 

[Onetap]

The instructions that came with the last manufacturer remote kit I did told you that the boiler PRV if unsuitable for discharge is to be tee'd into the boiler return.

I looked it up. Baxi do a remote PRV for their Neta-tec combi. The installation instructions say;

"4. A remote relief valve kit is available to enable the boiler to be
installed in cellars or similar locations below outside ground
level (kit no. 5121379).

5. A boiler discharge pump is available, part no. 720648301.
This pump will dispose of both condensate & high temperature
water from the relief valve. It has a maximum head of 5 metres."


I can pretty much guarantee that the installation instructions do not allow for connecting the PRV discharge into a CH pipe. Have you never seen a CH pipe blocked with sludge? Or a boiler operated with both the flow and return IVs closed? That may have become exciting if the thermostat had failed and it had carried on firing.

I'd suspect the primary boiler PRV would remain in place; it should never discharge unless the secondary PRV had failed.

In any event, item 5 above has the approved solution for both problems.

 

[JohnHarrison]

If I'm reading the original post correctly, there is a third problem. If you run the flue through an existing chimney opening, and it is 20 feet (say 6 metres) in length, then it will probably have two joins in it. Under current regulations these need to be accessible for inspection

Thanks for noticing that. I looked that up and they do not need them. Only if it runs through void spaces. A sealed dedicated chimney does not need an inspection plate. The Baxi Bermuda is flexible concentric one-piece flue, but the Baxi is not a combi.

 

[JohnHarrison]

They call the remote pressure valve the "secondary". As is activates first it must be the primary.

FFS! This has to be a wind up.

The manufacturers have got their terminology wrong now, have they?

It is called a secondary device because it is, secondary to and in addition to, the primary PRV which is on the boiler. The boiler PRV discharge is to be piped as per the instructions, to atmosphere. The secondary PRV does not replace the primary PRV.

It seems likely that you want to install your own boiler and are putting up these clueless ideas because you can't see a problem with them. The task is too technical for you, you need to employ a competent installer who will know the reasons for not doing things as you suggest.

This clueless idea is backed by Vailant and Baxi and they provide kits for it. I actually have a new Vokera SE. Nice boiler.

 

[JohnHarrison]

The instructions that came with the last manufacturer remote kit I did told you that the boiler PRV if unsuitable for discharge is to be tee'd into the boiler return.

I looked it up. Baxi do a remote PRV for their Neta-tec combi. The installation instructions say;

"4. A remote relief valve kit is available to enable the boiler to be
installed in cellars or similar locations below outside ground
level (kit no. 5121379).

5. A boiler discharge pump is available, part no. 720648301.
This pump will dispose of both condensate & high temperature
water from the relief valve. It has a maximum head of 5 metres."


I can pretty much guarantee that the installation instructions do not allow for connecting the PRV discharge into a CH pipe. Have you never seen a CH pipe blocked with sludge? Or a boiler operated with both the flow and return IVs closed? That may have become exciting if the thermostat had failed and it had carried on firing.

I'd suspect the primary boiler PRV would remain in place; it should never discharge unless the secondary PRV had failed.

In any event, item 5 above has the approved solution for both problems.

The discharge pump may be a solution after all as one maybe needed if a condensing combi is chosen. So it will do both functions. The flat is exempt and can have a non-condensing boiler, so may not need the pump and then the secondary prv is needed. I prefer the secondary prv as if the pumps is kaput and the prv on the boiler opens the pump will not take the water away and then a flood.

 

[JohnHarrison]

FFS! This has to be a wind up.

It is

JohnHarrison = WaterSystems, DrDrivel, BigBurner, GeorgeBramwell, RichardHansonGranville.

Oh, it's Drivel!

I've been away, I thought he must be dead by now.

That is on another thread. That man is not normal, and you are turning out that way. You do not know what the makers sell for sure...but know all the answers.

 

[TCCHeating]

I have installed the vaillant kit before

The kit comes with a cap for the boiler prv, a 2.5bar prv and a modified return isolation valve.

The modified isolation valve has a connection tee for the new prv pipework before the isolator.

 

[Biggles..]

It certainly does

One of the other brands is a much cheaper version.

Onetap- hows about posing up the kit instructions as they overrule the boiler ones!

 

[Onetap]

Onetap- hows about posing up the kit instructions as they overrule the boiler ones!

I don't have them.

I have installed the vaillant kit before

The kit comes with a cap for the boiler prv, a 2.5bar prv and a modified return isolation valve.

The modified isolation valve has a connection tee for the new prv pipework before the isolator.

Why would they cap the boiler PRV? If the secondary PRV operates at 2.5 bar, then the boiler PRV should never operate, unless the secondary had failed.

If what you say is correct, then I'd suspect it contravenes the relevant BS and I expect Vaillant will withdraw it at some time in the future.

 

[TCCHeating]

It has been available for many years now onetap. I very much doubt vaillant are going to withdraw it! They make the boiler so it is up to them to decide what is and isn't acceptable. And vaillant clearly think that capping the main prv and installing a remote prv is acceptable.

Ps. I think worcester have also just released a remote prv kit as well. Not sure how they implement it though.

 

[Biggles..]

Onetap- then maybe before shouting people down and claiming that it's all wrong, find them.

As TCC says the Vaillant kits been around years, Baxi were the first and use a similar method with adapted return valve, worcester have followed suit and I believe ideal have, the smaller manufacturers that don't make a kit are happy for the existing to go straight into the return but exchange the return valve for a straight through fitting.