Unvented Cylinder drain

[frank999]

An unvented cylinder will be installed in a ground floor cupboard, this level is below the outside level, making a through the wall drain un workable.

Running under the floor is a 110mm PVC soil pipe.

Would there be any issues putting a Boss Strap on it, and allowing the cylinders 'drain' to empty into the soil pipe.
In essence - any issues connecting an unvented hot water tank to a soil pipe, without a trap.

I presume as long as the connections are sealed - any foul odours cannot permeate ?

Any thoughts appreciated.

 

[dilalio]

What are you doing with the discharge from the cylinder?

 

[oldbuffer]

1. The cylinder "drain" is, I assume, what you mean by the D2 pipe which comes after the tun dish into which the TPRV and the PRV flow if activated.
2. It is not really a drain, but a way of disposing of excess water, which could be at very high pressure and very high temperature in the event of a fault.
3. This pipe can be plastic, but it must be of a high temperature type. I doubt if PVC is rated for the temperatures involved.
4. Without a trap, sewer smells can come back out of the foul pipe via the tun dish.
5. You may well need a pump - and they are eye-wateringly expensive.

 

[dilalio]

assume

You know what assume means mate?

For those who don't, to Assume makes an...
Ass(out of)u(and)me

 

[bernardgreen]

Discharge the tundish "drain" into a metal tank,

Fit the tank with a water detector that can initiate a safe shut down of the system as soon as any water comes out of the tundish.

If it is not visually obvious or routinely inspected then the water detector could also turn on an alarme to notify the home owner that the system has been shut down,

 

[Gasguru]

The unvented cylinder regs. (G3) are hopelessly out of date and very open to interpretation.
Even large water tanks/high temperature sump pumps are way outside the regs and it's just an assumption of compliance.
You need to determine what the G3 registered installer is willing to do since he will be signing off the work.

Perhaps using either PP or chlorinated PVC pipe in combination with something like a Hotun may enable you to discharge into the soil pipework.

https://hotun.co.uk/hotun-dry-trap-solution-for-large-unvented-water-heaters/

 

[JimCrow]

 

[dilalio]

@frank999?