Height of an Air Admittance Valve in a bathroom

[Paul Cockhill]

Hi Everyone

I am fitting an air admittance valve to a stack pipe in a bathroom, see pictures. A separate washbasin waste pipe and bath waste pipe are also connecting to the soil pipe.

I have fitted an anti syphon trap to the washbasin and a HepVo to the bath

My question is
Is there a minimum height the AAV has to be in the bathroom?

My clients want it as low as possible and boxed in. I know once it is boxed in there will have to be an air grill

Any advice greatly appreciated

Best wishes

Paul

 

[JVTrades]

I think you’ll find that technically it needs to be at least 600mm above the highest spill over point which is normally the basin. With air admittance on other appliances though it will probably be fine although there are other details about the property and any other facilities that need to be known to be sure

 

[Sharp Point]

It has to be above the highest level of appliances in bathroom.... usually the basin. I always put mine a metre off the floor.

 

[king of pipes]

Needs to be above the basin height . Kop

 

[chris watkins]

It has to be above the highest level of appliances in bathroom.. usually the basin. I always put mine a metre off the floor.

Why ?
If it blocks the water will overspill the Pan not the basin.

 

[chris watkins]

I just don't understand where all this requirement for costly waterless & anti-vac traps is coming from?
If this stub is on the ground floor it doesn't need the Durgo.

 

[Welder]

TBH Chris it's not for us to decide really. The OP had had BCO out so what they say goes. We know they may not know what they are about, but we can't argue as we're not there.

On a personal level I'd not fit one - if the lengths are as they appear!

 

[king of pipes]

Why ?
If it blocks the water will overspill the Pan not the basin.

Building regs Chris - my interpretation is if you have a sewerage back up you may not notice a boxed low fitted air addmitance valve leaking but a overspill from the toilet or basin will show immediately the valves should be visable and removable for maintenance above the spill over level for rodding access if its needed whether we agree or not we should all be fitting to the regulations . Cheers kop

 

[Paul Cockhill]

Hi Everyone
Many thanks for your reply. The bathroom is on the first floor and as I mentioned it has an anti syphon trap on the washbasin trap and an Hepvo to the bath

 

[Paul Cockhill]

I think you’ll find that technically it needs to be at least 600mm above the highest spill over point which is normally the basin. With air admittance on other appliances though it will probably be fine although there are other details about the property and any other facilities that need to be known to be sure

Thanks for your reply. Does it matter that it is on the first floor and the bath, washbasin and WC are the only pipes running to this soil pipe

Thanks Paul

 

[chris watkins]

Building regs Chris - my interpretation is if you have a sewerage back up you may not notice a boxed low fitted air addmitance valve leaking but a overspill from the toilet or basin will show immediately the valves should be visable and removable for maintenance above the spill over level for rodding access if its needed whether we agree or not we should all be fitting to the regulations . Cheers kop

Totally agree kop with the pan but does not need to be above the basin, on this one.
1. Water finds its own level so if the stack blocked & you were silly enough to carry on using the basin it would over still the pan.
2. OP has fitted an anti-syphon trap to the basin which is below the overspill of the basin which is one of the reasons I don't like them.

 

[Sharp Point]

I just don't understand where all this requirement for costly waterless & anti-vac traps is coming from?
If this stub is on the ground floor it doesn't need the Durgo.

Actually, that’s not quite true. The idea of the AAV is to prevent either negative or positive pre

Why ?
If it blocks the water will overspill the Pan not the basin.

Not if it’s on the ground floor and vermin control flaps have been or anti flood valves.
Maybe the requirement is a ‘ one fit for all’ type.

 

[chris watkins]

Actually, that’s not quite true. The idea of the AAV is to prevent either negative or positive pre

I don't think you quite understand how a Durgo works they can only prevent negative pressures by opening to allow air in. They can't no positive otherwise the foul smells would come out.

Not if it’s on the ground floor and vermin control flaps have been or anti flood valves.
Maybe the requirement is a ‘ one fit for all’ type.

If it is a stub stack (i.e. on the ground floor) it wouldn't need one anyway (unless the drain was deep)
Sorry don't understand
"Maybe the requirement is a ‘ one fit for all’ type" can you explain ?

 

[Welder]

Is it me?
I find it quite depressing that something as basic as a AAV is so misunderstood. That said, I suppose if you don't do 'wet' plumbing you are less likely to need to know...

 

[Sharp Point]

I don't think you quite understand how a Durgo work

Oh, okay then.

 

[Sharp Point]

I don't think you quite understand how a Durgo works

If you look at my sentence, it stops mid way... as I realised what I was typing was incorrect. I was quoting one of your posts.... ooops

 

[Sharp Point]

If it is a stub stack (i.e. on the ground floor) it wouldn't need one anyway (unless the drain was deep)

What’s not needed, a vermin trap or anti flood valve or stub stack

 

[dan_the_plumber]

Why ?
If it blocks the water will overspill the Pan not the basin.

It depends where the blockage is though. If the pipe blocks between the toilet height and the basin height, then the basin will over flow

 

[dan_the_plumber]

Totally agree kop with the pan but does not need to be above the basin, on this one.
1. Water finds its own level so if the stack blocked & you were silly enough to carry on using the basin it would over still the pan.
2. OP has fitted an anti-syphon trap to the basin which is below the overspill of the basin which is one of the reasons I don't like them.

On point 1. It depends where the blockage is. If the pipe blocks between toilet and basin, the basin will overflow

 

[chris watkins]

It depends where the blockage is though. If the pipe blocks between the toilet height and the basin height, then the basin will over flow

On point 1. It depends where the blockage is. If the pipe blocks between toilet and basin, the basin will overflow

So you have seen lots of 100mm vertical stacks block then have you dan?

 

[dan_the_plumber]

So you have seen lots of 100mm vertical stacks block then have you dan?

Yes Chris, yes I have

 

[chris watkins]

What’s not needed, a vermin trap or anti flood valve or stub stack

An Automatic Air Admittance Valve would not be required on a stub stack on the ground floor.
An access cap is all that is required to close the end.

 

[chris watkins]

Yes Chris, yes I have

interesting, what with?
Because I have done a lot of drainage & the only time I have ever come across a vertical section of pipe becoming blocked it when a cast iron one froze. Not a particular common occurrence & even less likely on a short piece of 110mm vertical uPVC between a WC branch & a 32/40mm boss for a basin, I think you would agree.

 

[Sharp Point]

An Automatic Air Admittance Valve would not be required on a stub stack on the ground floor.
An access cap is all that is required to close the end.

So why do thousands of plumbers install them then, are they all wrong as well?

 

[Sharp Point]

Chris, you do realise I am talking about if wastes from other appliances are connected via boss ... solvent weld or drill out boss