Internal drain for tundish valve discharge from UVC

[Chanmenie]

Is it ok to plumb the discharge pipe from the UVC tundish valve into an internal drain if using a Hepvo or mcalpine self sealing waste valve.

the UVC will be on the ground floor so I was planning on running a waste pipe under the slab to come up into the UVC cupboard.
Does the pipe under the slab have to be 110mm ? 
or can I branch off the 110mm pipe that will provide drainage for the washing machine and water softener with something smaller ? 

[ProDave]

The pipe will need to be capable of accepting boiling water, so not your average PVC waste pipe. Someone with a better memory than me will come along I hope and tell you what it is.

[Chanmenie]

I found this which shows discharge to soil stack

so presumably discharge soil pipe is ok 

 

https://www.nhbc.co.uk/binaries/content/assets/nhbc/tech-zone/nhbc-standards/tech-guidance/8.1/discharge-pipes-from-unvented-hot-water-storage-systems-.pdf

 

 

Edited June 25, 2022 by Chanmenie

[PeterW]

Yes but you cannot use polyethylene pipe - you need to check the spec and it has to be stamped BS EN1451 which is usually polypropylene. ABS and solvent weld are also not suitable. 

[Chanmenie]

3 hours ago, PeterW said:

Yes but you cannot use polyethylene pipe - you need to check the spec and it has to be stamped BS EN1451 which is usually polypropylene. ABS and solvent weld are also not suitable. 

Hi @PeterW  yes I read that on the G3 BR document, the D2 discharge pipe must be metal or polypropylene, but on the link I attached above it says the soil pipe can be PVC-U to BS1329 / BS 1453 which Osma soil pipe is. 

[PeterW]

5 hours ago, Chanmenie said:

Hi @PeterW  yes I read that on the G3 BR document, the D2 discharge pipe must be metal or polypropylene, but on the link I attached above it says the soil pipe can be PVC-U to BS1329 / BS 1453 which Osma soil pipe is. 

You need the minimum distances as per G3 to ensure the water isn’t 100°C/steam as it hits the stack but other than that it’s fine. 

[Chanmenie]

9 hours ago, PeterW said:

You need the minimum distances as per G3 to ensure the water isn’t 100°C/steam as it hits the stack but other than that it’s fine. 

Thanks @PeterW the only minimum distance I can find is the 300mm minimum length of pipe below the tundish valve before any bends, or am I missing something 

[PeterW]

Yep you’ll need 300mm drop after the tundish before any bend - given most tanks are 14-1500mm up when the PTRV exits the tank it shouldn’t be an issue. 

[Chanmenie]

13 minutes ago, PeterW said:

Yep you’ll need 300mm drop after the tundish before any bend - given most tanks are 14-1500mm up when the PTRV exits the tank it shouldn’t be an issue. 

Thanks again @PeterWthat’s how I read it, so as I’m building with ICF (Isotex) 

I do have the option to use traditional method of running a copper pipe out through the wall and fitting a cage round it, or would it be preferable to use the HepVo waterless trap and discharge to an internal drain.