Soil stack
- Thread starter Joe11red
- Start date
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You would have to get on the roof to fit a cap, so you might as well remove it and slip a tile/slate back over.
We did the same thing, because the old soil stack was running up the wall of the bathroom and it looks a little unsightly outside sticking out of the roof.
So cut it off and removed it, replacing with air admittance valve.
Dont know about in your circumstances, but in ours we removed the pipe sticking out of the roof as well, and just shoved a new roof tile in its place, meaning it is no longer evident a pipe was ever there.
So cut it off and removed it, replacing with air admittance valve.
Dont know about in your circumstances, but in ours we removed the pipe sticking out of the roof as well, and just shoved a new roof tile in its place, meaning it is no longer evident a pipe was ever there.
Have you another vent on the drainage system elsewhere on the property? Blocking off the only vent could lead to problems, and/or smells in the bathroom!
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No it won't, that's what an air admittance valve is for!
When you flush the toilet it creates a negative pressure which opens the valve allowing air in, then after it closes again so no nasty smells.
That's wha they are designed for, some properties now don't even have a conventional vent because they have an air admittance valve instead which does same thing.
When you flush the toilet it creates a negative pressure which opens the valve allowing air in, then after it closes again so no nasty smells.
That's wha they are designed for, some properties now don't even have a conventional vent because they have an air admittance valve instead which does same thing.
An AAV does exactly what it says on the tin, it lets air in to the system. What it wont do is relieve any positive pressure, which can, under certain conditions, result in foul air being bubbled back into the room through the traps.
Regs state: 'To prevent water seals in the traps being lost by pressures which can develop in the system, discharge stacks should be ventilated. Where there is no open ventilation on a drainage system or through connected drains, alternative arrangements to relieve positive pressures should be considered.'
There are conditions, such as a blockage, which can result in foul air being displaced into the room if the stack and/or drain is not adequately ventilated.
Regs state: 'To prevent water seals in the traps being lost by pressures which can develop in the system, discharge stacks should be ventilated. Where there is no open ventilation on a drainage system or through connected drains, alternative arrangements to relieve positive pressures should be considered.'
There are conditions, such as a blockage, which can result in foul air being displaced into the room if the stack and/or drain is not adequately ventilated.
Individual properties should be ventilated, otherwise we could all shut down our air exhaust with an AAV.
But we don't do we as it is not allowed.
Another way built up stench can find its way in is when the smaller traps become disturbed i.e. shower and basin wastes.
People that think they can simply shorten any old stack to below a roof line and plonk on an AAV need a lesson in building. Some you can and some you should not.
But we don't do we as it is not allowed.
Another way built up stench can find its way in is when the smaller traps become disturbed i.e. shower and basin wastes.
People that think they can simply shorten any old stack to below a roof line and plonk on an AAV need a lesson in building. Some you can and some you should not.
Was able to here, because there should only ever really be a negative pressure on our property.
Its located at the very end of the soil pipe run outside, and every other house on the run has their vent pipe still.
but because ours is on the end, any water flowing along the drain will only ever generate a negative pressure.. positive pressure can only occur on the other houses next to us on the soil run.
Its located at the very end of the soil pipe run outside, and every other house on the run has their vent pipe still.
but because ours is on the end, any water flowing along the drain will only ever generate a negative pressure.. positive pressure can only occur on the other houses next to us on the soil run.
Well I`ve learned something new ! - I thought the other houses could have AAV`s and the one @ the head of the drain should be vented - summat like a max of 10 houses in total 
I suppose it depends on which very end we`re talking about I kinda mean main sewer end v. head end
I suppose it depends on which very end we`re talking about I kinda mean main sewer end v. head endthe very end of the run, head end will always be negative pressure.. as water infront of it will generate a suction effect.
So should be no problem with using an Air admittence valve.
However, the opposite end, the sewer end will always be positive pressure, so as above air admittence valve is no good because it wont relieve a pressure build up... which is what happens infront of the water.. as the water flows a pressure builds up infront.
So as you say, in theory all houses to a maximum of 10 can use AAV as long as the house before the connection to main sewer has adequate vent pipe to relieve pressure build up.
So should be no problem with using an Air admittence valve.
However, the opposite end, the sewer end will always be positive pressure, so as above air admittence valve is no good because it wont relieve a pressure build up... which is what happens infront of the water.. as the water flows a pressure builds up infront.
So as you say, in theory all houses to a maximum of 10 can use AAV as long as the house before the connection to main sewer has adequate vent pipe to relieve pressure build up.
Sorry, but i'm with Nige here. The head of the drain should be ventilated, that to me is the highest point which will always be the end of the run. A WC flush is never going to completely fill the pipe, but should peak flow conditions ever occur, yes the water will create a positive pressure in front, but will also create a negative pressure behind it.
There are conditions when air flow through a drain can be reversed, high pressure water jetting can be one cause. Should a neighbour experience a blockage, or the Water Authority decide to carry out maintenance on pipework that involves jetting, then such conditions can occur. We have a list of checks we are expected to carry out at work prior to commencing any jetting operation to try and prevent any such positive pressure occuring where it's not wanted.
Blowing the contents of the sewer into someone's bathroom is not a pleasant experience for anyone, and yes, it has happened in spectacular style on plenty of occasions! (Not to me I hasten to add, but have seen picture of the aftermath and it's not pleasant.... )
There are conditions when air flow through a drain can be reversed, high pressure water jetting can be one cause. Should a neighbour experience a blockage, or the Water Authority decide to carry out maintenance on pipework that involves jetting, then such conditions can occur. We have a list of checks we are expected to carry out at work prior to commencing any jetting operation to try and prevent any such positive pressure occuring where it's not wanted.
Blowing the contents of the sewer into someone's bathroom is not a pleasant experience for anyone, and yes, it has happened in spectacular style on plenty of occasions! (Not to me I hasten to add, but have seen picture of the aftermath and it's not pleasant....
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