air admittance valve problems

[mattC44]

Hi,

I have just had an extension built. A new soil vent stack was installed for 2 toilets, 2 basins and a shower tray.

The vent stack is vented into the garage loftspace with the use of an air admittance valve.

Very early on after completion I had problems when flushing one of the new toilets. The water level would rise and it would take longer for the water to clear. The plumber, returned and said he had adjusted the valve.

I started reading about these valves and struggled to think how this could be carried out. The top of the vent stack was above the plastered garage roof. There was a small hole where the soil pipe ran. I cut a larger hole only to find that a section of the pipe and the valve had been removed and was lying above the ceiling. The pipe was open and venting into my garage roofspace.

I have had many problems with the building firm and would appreciate any opinions on the above before I contact them.

 

[Hugh Jaleak]

AFAIK these are not adjustable, valve is spring loaded, opens against spring pressure to admit air when pipework is under negative pressure (i.e. W.C. being flushed) then springs shut again to prevent smells escaping.

Did the 'adjustment' (or removal) of the valve allow the W.C. to flush properly?

 

[mattC44]

thanks for the reply.

Yes it allowed the wc to flush correctly. I'm very concerned about the open vent in the roof space?

 

[Fluffster]

Basically it is not to current regs so they are obliged to make it conform either by re attaching the AAV or open venting it 900mm above any eaves/opening/access to your property.

I take it the pipe terminates above the spill level of the highest outlet usually your basin?

Pete

 

[mattC44]

I take it the spill level is the top of the basin. If so then the AAV is about 200mm lower.

Also, when the new garage roof was installed in place of the existing flat roof there was a rainwater down pipe left sticking up from the ground about 2m. This was left open and is connected to the same drain as the soil vent stack. The drain was block last week and I had to get them flushed out. This pipe was stinking. I have stuck a plastic bag over it for now.

 

[Fluffster]

You are correct top of basin so the vent pipe is too low.

If the old rain water is connected to a combined sewer then it should have a trapped gully to prevent smells from rising up. Make sure it has water in the trap.

If you are having blockages already I would get that soil pipe sorted pronto.

Pete

 

[mattC44]

Thanks for the advice.

One last question,

there was a pressure relief pipe for the combi boiler exiting the house where the new garage roof tied in.

This was taken out and the a new pressure relief pipe ran into the condensate pump. This has a small plastic pipe that runs into the main loft of the house and into the original vent stack pipe. Is this acceptable?

 

[Fluffster]

If you are saying that a pressure relief pipe has been terminated into a condensate pump well this is a big no no as the temperature, pressure and flow would exceed the pumps inlet allowances.

Get Gas Safety out to inspect if you are not happy with the installation/adjustment of the boiler.

Pete