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Plumbing
Cast iron stack pipe
The current cast iron vent pipe I have is a single 90/100mm pipe serving 2 flats. Each of the flats has a:
- kitchen sink
- Washing Machine
- 1 Toilet
- 1 Bath
- 1 Bathroom sink
- Drain To Combi Boiler
Could I cut the pipe off 400mm above the upstairs flat toilet (highest drain entry point of both flats) and add a Air Admittance Valve?
I'm planning a bathroom remodel but don't want boxing up the wall for the current cast iron pipe as I'm tilling the full bathroom.
Thank you in advance for your advice
Edit:
Or could I use a 90° Elbow to go throw the exterior wall behind the toilet then vent the pipe on the outside of the wall? Is this possible and allowed
2 Answers from MyBuilder Plumbers
Best Answer
no this would not be a good idea,aav ,s can fail and they do nothing to protect against back pressure in drains and soil stack,also this may be the head of drains vent,your local building regs might not allow this.yes that would be a better idea,but you will have to speak to building regs department.
Answered 31st May 2020
If the existing vent pipe is cast iron, the internal diameter will not be 90/100mm, they are a different size. So, you will need to by a converter to convert the inner diameter to fit the AAV.
You cannot add the AAV directly to the other toilets waste pipe. You will still need a 1m high AAV internally. If you vent outside you will need the stack pipe to be 1m above any window.
Answered 28th Jun 2020
