Unvented cylinder discharge pipe location

[Tigermad]

I posted a year or so back about the total messed up install I had of an unvented system. I can finally get this resolved. I’m having the cylinder moved from the loft into the airing cupboard. At present the discharge pipe runs down the outside side of the house from the loft.

Due to the move the discharge pipe would need to be run down the front of the house which I’m not happy with. So the installers say the pipe can be fed into the waste pipe under the bath.

Is this ok to do? I don’t want to replace one major problem with another. Does all the waste pipe need changing to heatproof? Also I see online it keeps mentioning the soil stack when doing this. Some bright spark before I moved in cut off the soil stack in the loft. There are valves on each toilet but the en-suite smells with shower badly now an again. I have read the correct tundish needs to be fitted to stop smells also from the waste.

Does the soil stack also need sorting out?

 

[Scott_D]

The soil stack should have a durgo if it terminates internally.
UV discahrage has to follow many rules eg type of pipe used, it must only be for the cylinder discharge ( not simply joined to another pipe) clipping distances, pipe lengths & tundish used etc etc

 

[Tigermad]

The soil stack should have a durgo if it terminates internally.
UV discahrage has to follow many rules eg type of pipe used, it must only be for the cylinder discharge ( not simply joined to another pipe) clipping distances, pipe lengths & tundish used etc etc

Thanks for the reply. So as long as they follow all the regs it is allowed? I always thought the pipe needs to be external for safety and that you need to see when water comes through it. How would I see this if it’s joined to the waste pipe?
There are durgos on every toilet cistern.

 

[Scott_D]

Yes it’s allowed but connecting to the bath waste isn’t correct.
The correct tundish setup would make water visible at the cylinder.
Not sure what you mean by durgo on each cistern.

 

[Tigermad]

Yes it’s allowed but connecting to the bath waste isn’t correct.
The correct tundish setup would make water visible at the cylinder.
Not sure what you mean by durgo on each cistern.

Sorry I mean there are 3 Durgos on the 3 toilet pipe work not cistern.

So the plumbers will be doing it wrong then by using the waste pipe under the bath? I can’t seem to win here. I have them booked in for a few weeks time.

 

[Scott_D]

It can’t tee into the bath waste.
It needs to go back to the soil stack with a dedicated pipe.

This is why retro fitting UV cylinders isn’t always easy. Also getting 22mm cold from the stop tap creates of work.

 

[Tigermad]

It can’t tee into the bath waste.
It needs to go back to the soil stack with a dedicated pipe.

This is why retro fitting UV cylinders isn’t always easy. Also getting 22mm cold from the stop tap creates of work.

I already have the 22mm pipe from the stop tap since the cylinder was in the loft. I have messaged the installer for their opinion on all this.

 

[SimonG]

The boxing around the air admittance valves needs to be vented to allow the aav to function properly.

 

[townfanjon]

You can only use the soil pipe if its capable of taking an unvented discharge, not all are .

 

[Tigermad]

Thanks for the replies. Queried this with the installer and this is his response.

it will be tee’d off the existing waste pipework closest to the stack beyond the bath. The waste pipe will then be run all the way back to the cupboard where it will have the appropriate fittings.

If you would rather then we can just run the discharge externally but for visual reasons I would suggest we run it to waste internally.

He also showed me this pic for reference.

 

[Scott_D]

That’s is the correct guide to follow