You've just seen the main soil and vent pipe to this property
That pipe goes right up onto the roof and the fowl gases escape through the vent at the top there
You've also seen the trench that contains the new soil and vent pipe that we've installed and that's so that we can put this toilet in
into the new bathroom here and beyond that the pipe then goes up into the room above
which we'll see in a moment where we're going to install another toilet. This particular
soil and vent though because we have one already that goes to the vents right the way
through the roof into outside air this particular soil and vent pipe can have something called
an air admittance valve on top of it and this air admittance valve when the toilet is flushed
The valve opens within here and the air is sucked in through that valve down the pipe
and kind of chases the effluent out into the manhole and the foul gases can then escape
up the main soil and bent pipe through the roof and out to open air
This valve then shuts allowing no foul gases to come back into the room
I'll explain that more fully when we get upstairs that that's the air admittance valve that we're going to put on
upstairs. So we're upstairs now where the new soil and vent pipe comes through the floor
It's going to be extended by a piece of grey plastic. I don't have any more grey plastic at the
moment. Grey pipe is used out of the ground, brown pipe in the ground. So we can demonstrate
with a piece of brown for now. The soil and vent pipe is going to continue up this wall. We're
going to put a couple of bends on so that gets closer to the wall And then the dergo valve or the air air of mintants valve goes on top of the pipe This particular air admittance valve is solvent weld so we will put some solvent
weld adhesive on the inside of that collar and on the outside of the grey pipe when we've cut it
and that will sit on there, twisted a couple of times and that will be set solid
The whole thing then goes down onto the stand pipe that we've got there, the sort of
oil invent pipe that we've got there. When the chain is flushed, this valve senses the
vacuum that's being caused by everything running down the pipe and the valve opens
You can actually hear it. You can hear the valve. The valve opens when it feels that water's
being sucked or air is being sucked away from it. It opens and it allows fresh air to come into the pipe
so the vacuum that would be created is allowed to move along because there's air coming in behind it
The minute that stops running, that valve shuts again so that, and none of those foul gases can escape out of this particular valve
They will all then go to the soil and vent pipe that goes out of the roof and escape
The termination of this air admittance valve should be above the highest outlet in your bathroom plumbing
The highest outlet is normally the overflammal. to a hand basin in the bathroom
So this air admittance valve should be a little bit above that. Okay, so that's an air admittance valve
That's how it works and why we install them. It saves you putting a soil and vent pipe
a secondary soil and vent pipe, right up through the roof and into the roof again
This will allow the foul gases to escape through the main soil and vent pipe
but it will allow air in to make sure that that process runs smoothly
An air admittance valve being installed by DR by ductal