Pressure relief valve off CH pipe

[Biggles..]

If you search vaillant p/n 0020094185
You'll see what you get, note the modified return valve

 

[Onetap]

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.

The arrangement that has been described on here is wrong and both you and LeeC have evaded the relevant question.

If you're going to discharge the boiler PRV into a CH pipe, then how can you, as the installer, guarantee that CH pipe is not, or will not become, obstructed with sludge, the products of corrosion from the CH system?

The relevant BS for sealed system domestic boilers contained a requirement for a PRV on the boiler ( or it did the last time I looked at it some years back); not some metres away on the end of a bit of dodgy dual-purpose pipe. That is not a requirement that needs explanation and it is not something that could be amended, by the installer or the manufacturer.

I very much doubt vaillant are going to withdraw it!

They might, if it kills someone.

 

[Biggles..]

I'm confused....if the boiler prv operates at 3bar what do you think will already have happened when using the remote kit at that pressure.

How can ensure that the face of a standard boiler prv will not be blocked with sludge, obstructed, corrosion etc even If you don't use a remote kit?

Don't forget, British standards actually carry no weight, the manufacturer can adopted any practice the like, have it tested and certified.

 

[Onetap]

How can ensure that the face of a standard boiler prv will not be blocked with sludge, obstructed, corrosion etc even If you don't use a remote kit?

It shouldn't open at all until it functions. Then the discharge pipe should be unused and clear, allowing the unimpeded discharge of steam and water to the atmosphere.

You can't guarantee that the innards won't get blocked, but sludge would most probably block and perforate the heat exchanger, rather than settle in the PRV.

So if you use part of the CH pipework as a discharge pipe, how do you ensure it is unobstructed? In this context, I'm thinking of 15mm pipes I've seen closed up to about 8mm.


I don't think I understand the first part of your post. If it means what I think, then the short answer is; frozen. That has happened in the UK and that is why you have a PRV on the boiler and do not rely on the operation of a remote device.

 

[Biggles..]

We can go round and round all day, I've seen PRVs that fail to open, completely blocked.

By your own boiler posting where it tells you a kit is available when the discharge is in a basement or cellar... How do you comply with the other bits your banging on about, you know terminated in a safe place, open to atmosphere, outside the building...isn't the bit that ruins your party the statement about continuous fall.

Like it, or not, these kits are here, the instructions that as yet you haven't got tell you how to fit it, prv back into the heating return, remote valve located to meet the original above ground conditions.
Each of the big manufacturers now offer them, all with their own twist, like I said back on page 1, consult your manufacturer they'll tell you if and how to use their kit if they do one.

If your not happy, then I don't care, it's not wrong, the manufacturers say so, their boiler, their blow off kit, their liability.

 

[Onetap]

We can go round and round all day, I've seen PRVs that fail to open, completely blocked.

By your own boiler posting where it tells you a kit is available when the discharge is in a basement or cellar... How do you comply with the other bits your banging on about, you know terminated in a safe place, open to atmosphere, outside the building...isn't the bit that ruins your party the statement about continuous fall.

Like it, or not, these kits are here, the instructions that as yet you haven't got tell you how to fit it, prv back into the heating return, remote valve located to meet the original above ground conditions.
Each of the big manufacturers now offer them, all with their own twist, like I said back on page 1, consult your manufacturer they'll tell you if and how to use their kit if they do one.

If your not happy, then I don't care, it's not wrong, the manufacturers say so, their boiler, their blow off kit, their liability.

You're not going to answer the question then. There's a flaw in the concept.

Continuous fall; ensures the discharge pipe isn't full of water. The last PRV I saw in a basement had a drain capilliary run to the floor. It would make the floor wet, but the discharge pipe (about 2" ISTR) was routed to the outside.

 

[Biggles..]

Apart from plant rooms I ain't seen a basement with a drain, ever!

If you have any questions over concept, maybe try the manufacturer....for a guy that's not seen a remote kit, fitted a remote kit or read the instructions, you do protest too much!

 

[Onetap]

As a guy that wouldn't fit a remote kit, for the reasons stated, I doth protest too little methinks.

 

[Dan Robinson]

Apart from plant rooms I ain't seen a basement with a drain, ever!

Will show you one on the 19th.


Oh, hang on. That counts as a plant room . Still can think of a few in Laaaandan.

 

[Biggles..]

Better send me another invite then Calander boy.

 

[TCCHeating]

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.

The arrangement that has been described on here is wrong and both you and LeeC have evaded the relevant question.

If you're going to discharge the boiler PRV into a CH pipe, then how can you, as the installer, guarantee that CH pipe is not, or will not become, obstructed with sludge, the products of corrosion from the CH system?

The relevant BS for sealed system domestic boilers contained a requirement for a PRV on the boiler ( or it did the last time I looked at it some years back); not some metres away on the end of a bit of dodgy dual-purpose pipe. That is not a requirement that needs explanation and it is not something that could be amended, by the installer or the manufacturer.

I very much doubt vaillant are going to withdraw it!

They might, if it kills someone.

Hang on a minute!

I never expressed any opinion on what the op suggested regarding the external prv and teeing the boiler prv into the return pipe.

I just simply posted that vaillant do a kit. I have used this kit before. And if vaillant are happy, then I 'm happy

Couldn't care less what BS say's. I was always taught that what the mi's say is final. So if the mi's told me i can only fit the boiler upside down, that is what I would do

Ps. I agree with you onetap. What the op suggested is wrong imho. And i would never do what he is suggesting unless the boiler manufacturer specifically stated that it was allowed.

 

[JohnHarrison]

Ps. I agree with you onetap. What the op suggested is wrong imho. And i would never do what he is suggesting unless the boiler manufacturer specifically stated that it was allowed.

Would you seal off the combi PRV and just have a 2.5 bar remote PRV? Many makers do not have these kits, so what I stated, keep one at the combi and another to atmosphere satisfies all.

 

[TCCHeating]

No! Of course not!

You're missing the point mate.

I wouldn't do anything that was not allowed by the manufacturers.

As far as I can see. You never stated the boiler make or model.

It could be that what you are suggesting is allowed by your boiler manufacturer.

Best thing to do is ring them and ask.

If they say no. Then don't do it.

Simples!

 

[JohnHarrison]

You're missing the point mate.

I wouldn't do anything that was not allowed by the manufacturers.

As far as I can see. You never stated the boiler make or model.

It could be that what you are suggesting is allowed by your boiler manufacturer.

Best thing to do is ring them and ask.

If they say no. Then don't do it.

Simples!

Combi will be either: Vokera SE, Intergas or an ATG. I will check it out with the makers once the boiler make is pinned down.

 

[Biggles..]

Without dragging this thread on and on.

I'd be interested to read this so call BS for boilers, as it seems that the 3 boiler john is looking at all have a different take on it and will no doubt make their own decision on what they can do remotely.
So vokera use a standard PRV arrangement, ATAG use a combined PRV/Condensate arrangement utilising a tundish and 11/4waste directly to the boiler this connection to the return is unlikely, intergas added a prv as an afterthought for the UK, this is positioned on the flow pipe after the valve by a standard 22-1/2 tee arrangement.

Most documents I've read actually refer to a sealed system requiring a means for The pressure to be relieved, appliance manufacturers could just simply chuck a prv in the box and tell you to fit it, but they don't, they incorporate it to ensure its done.
If the so called boiler BS stipulated that all appliances should have a prv fitted within, what happens with heat onlys, the manufacturer is quite happy for you to install them in a sealed system, they don't sell a kit that means you can retrofit a prv into the boiler, they assume you'll fit a robokit again with no advice on where to put it.
They're not interested where, just that the system has a means of relief once sealed.

Simplest solution for this is to ask the manufacturer.