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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

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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
 
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.
 
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!
 
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
 
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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
 
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
 
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.
 
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.
 
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 ?
 
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
 
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.
 
Chris, you do realise I am talking about if wastes from other appliances are connected via boss ... solvent weld or drill out boss
 
An air admittance valve is just that, it admits air, it isn't supposed to let air or water out. Now occasionally they do fail/stick and let sewer gas out or if you have a clog will leak some. Personally I don't like them and I rarely see an instance where you couldn't have just run a proper vent pipe. That said they do serve an important purpose and can help waste drain more properly.

Generally when we fit them they go under a sink in the back of the cabinet as high as possible. Technically they should be above the flood rim of the highest appliance which is almost always a sink/basin.

I snake drains as my primary function. I have seen enough clogs in vertical 100mm/4" pipe to know that they can happen and it's always been old rusty cast iron pipe. They only time I like AAV's is when I can unscrew them and use them for a snaking point. Often I put a glove around them and vacuum out the clog. In that case a regular vent would be worse for me but I can't help but think that the drain wouldn't have clogged in the first place if it was properly vented.
 
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

View attachment 34965

View attachment 34966

The Floplast AV110G Air Admittance Valves can be fitted below the flood level of the highest appliance. These valves are very good and I've not had one single problem with them, and even have one fitted in my own house. It's a good space saver as it's fitted inside the cabinet for a back to the wall loo and eliminates the boxed in stack going up the wall.
Make sure that air is allowed to circulate near these valves though or they won't work. Fitting a small vent grille is fine if boxing it in.
 

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