PRV off a combi going vertical

[Paul Barker]

Don't forget from the unvented training that all prv's have a second safety which is that the cap on the face of the red part blows off if the prv fails to release the pressure,

First I've heard of that. Are you sure you don't mean the T&PRV? At what pressure is this supposed to happen?

The expansion valve the tprv and the prv all blow apart if their pressure is exceeded. Exceeded by how much I don't know, but certainly this additional safety is built into them. AFAIK it is always built into the cap.

 

[oilman]

................

Unless someone systematically tested the PRV (and who dares to do that when servicing a boiler?) .....

Always

the blockage would remain undiscovered, at least until a critical situation arose. Then system pressure would rise until something else gave way to release the pressure, perhaps a radiator or pipe connection near a child.

Or expansion vessel with no air left, bursts.

 

[Alfredo]

So come on then..less of the titanic scenarios..what would you guys do when presented with an upstairs flat with concrete floors and the only place you can install a boiler is centrally...walk away from it one presumes "can't be done missus". Not so easy if you are on contract.

I'm just waiting to hear you say you'd dig up the concrete floors to keep it low level

Alfredo

 

[Paul Barker]

Actually the first answer which comes to mind is "it isn't safe and I wouldn't do it, no doubt you will get someone to do it for you but not me, goodbye".

Then I thought, ask the manufacturer if they would approve a sump and pump system, if they won't you can't do that either.

The only other safe option is to allow for a flood if it ever goes off, like the guys in Scarborough who fitted all the worcesters in Gibson Court some 20 years ago.

 

[chrishutt]

what would you guys do when presented with an upstairs flat with concrete floors and the only place you can install a boiler is centrally

The best solution is to fit a new PRV on the flow or return pipe at a high enough level to allow for a downward sloping discharge. If the flow/return pipes don't rise to that level an extension pipe could be fitted to a PRV at the appropriate level.

The problem with this approach is that any integral boiler PRV would have to be capped off (unless the extension pipe to the new PRV were to replace it) and any integral isolating valve between boiler and PRV removed (or fixed permanently open). Such modifications would require the manufacturer's approval, which I doubt would be forthcoming.

In some cases one could fit an open system version of a boiler and fit external sealed system components (although I doubt if this option is available for combis). Then the PRV arrangement would not involve any alteration to the boiler as supplied and would simply comply with general sealed system principles.

 

[Paul Barker]

OH why didn't I think of that, brilliant.

PS if you live in Gibson court and you are worried have a look on top of your boiler there is a brass part with a red plastic nurled knob on it, if there isn't a pipe leading outside from this part there should be, you do need to worry. Call someone corgi registered to come and retro fit it.

Your pipesizing is also apaulingly inadequate but you will have to blame the builder for that. Little can now be done apart from running a whole load of 28mm pipes up the outside of your building on the side facing the sea. You need to get together as a community and organise this really. Whether the original builder is still in business to be sued for the cost is highly unlikely.

Don't worry you are not alone, most of Scarboroughs tall buildings are in the same fettle.

 

[ChrisR]

One of the makers told me I could go up out of a basement with a prv, can't remember which, may have been Alpha.

Wot about Megaflo discharges from a basement installation, anyone been round the loops on that one?

 

[chrishutt]

ChrisR, when did you get back from Antarctica?

 

[Paul Barker]

yes comes into citb unvented training. You must have the 300mm drop below the tundish then you can sump and pump it. Basically whether thje sump and pump can cope with the flow is more a matter of practicality than safety, the safety side is covered if you just discharge it into a bucket. Yopur only conscern is scalding the loverly good folk of the house.

Having said that I did a basement one in London and put the expansion vessel which sat on top up through the floorboards into the kitchen cupboard above so that I could get required drop and reach a gulley. To check pressure in ev just open the cupboard door, lift off the pan and bob's yer uncle, easier than finding a stop cock.