Heat proof "waterless" valve for Unvented cylinder T&P connection to soil stack

[GeoffG]

I have just had an unvented cylinder fitted, and the T&P valve is connected as per regs via a tundish, and then into the soil stack using a copper pipe.

But I've had to ask the plumber to come back, because it looks like he hasn't done anything to prevent sewer gases from coming into the property via the tundish, and there is an odd smell in the cylinder cupboard.

From our quick chat on the phone, I'm not sure if he's familiar with so-called waterless valves, as recommended for this purpose, for example, here:
Guidance: Discharge from storage cylinders into pipework systems
(See also associated diagram below)

But when I have searched for such valves, there don't seem to be many advertised, and the HepVo ones for example get very poor reviews on Amazon, with people say they don't exclude sewer gases properly, or that they get blocked frequently.

So my question is, can anyone recommend a good one that is suitable for this purpose, in terms of temperature tolerance and reliability, and that is also readily available from plumbers' merchants?

 

[Stigster]

I fitted a Hotun once and it wads a load of S**t, no way it can take a decent flow rate without over spilling everywhere.

Screwfix do something similar, not sure whites its called now but Ive used it and it worked well.

My apologies, what I have here I misidentified as a Hotun tundish but it is actually an RWC manufactured one and it works well.

15 x 22mm Dry Trap Teslatun Tundish - TUND500005

15 x 22mm Dry Trap Teslatun Tundish - TUND500005, now available from Advanced Water Company

www.advancedwater.co.uk

 

[ShaunCorbs]

Yes I fit the Tesla ones as well there great nice and compact and works well

 

[GeoffG]

Thanks for all the replies! Sorry, missed them until now because notification went into spam!

Re: photo of install - see below. As you can see, I have a Tundish, and limited space, so I'm thinking that the best thing from the point of view of space and accessibility, is something below the Tundish like in the diagram I posted for the guidance notes. (The scale isn't obvious from my photo, but space and access is pretty tight).

The important thing is to exclude sewer gasses reliably, while of course being safe in the event of the T&P valve venting. Some reviews said that the HepVo ones didn't do that from the start.

The only ones Screwfix sell at the moment are Osma, but it doesn't say what temp it will withstand.

View attachment 41380

P.S. The tundish and associated pipe really are v hard to access without uninstalling the cylinder temporarily(!) So will one of these valves be OK near the soil stack on its side (see photo below, pipe going into black boss), or must they be installed vertically?

 

[Stigster]

They need to be installed vertically, all types of tundish and waterless valves in this particular application must be installed vertically and the regulations specify this.

The tundish must also have a minimum of 300mm of vertical pipe below it before the first bend (if you do use a waterless trap, the trap can form part of that 300mm section). That first bend should also be a "pulled bend" as in made with a pipe bending machine although I believe a 90 degree fitting is acceptable as long as it can be shown not to back up and overflow the tundish in the discharge condition.

 

[Belli]

This is what i would use would definitely stop back smells and isn't open so no splash out either

 

[ShaunCorbs]

This is what i would use would definitely stop back smells and isn't open so no splash out either

not rated for unvented

 

[Belli]

not rated for unvented

Ah just looked at specs overflow condense only

 

[MOSSEP]

My apologies, what I have here I misidentified as a Hotun tundish but it is actually an RWC manufactured one and it works well.

15 x 22mm Dry Trap Teslatun Tundish - TUND500005

15 x 22mm Dry Trap Teslatun Tundish - TUND500005, now available from Advanced Water Company

www.advancedwater.co.uk

The RWC one in your link is what Screwfix sell, they are actually pretty good