Adding air admittance valve between bath and shower traps

[Pistol1]

Occasionally we get some bad smells when the bath is emptying, accompanied by gurgling sounds from the shower trap. I think this means the bath emptying is sucking the water out of the shower trap, which can be addressed by adding an air admittance valve.

Am I right in thinking that the AAV should be positioned as high as possible (ideally above the height of the bath overflow)?

I've added some pics to hopefully outline the situation. It's 1.5 inch solvent welded pipe, I'm hoping there's enough play in the pipework to allow me to add in a tee so I can fit a vertical section with a Mcalpine VP2W on top.

Untitled

• Pistol1
• 14 May 2014
• 1

Untitled

• Pistol1
• 15 May 2014
• 1

Untitled

• Pistol1
• 14 May 2014
• 1

 

[picasso]

If you can run in a seperate pipe for the bath.

 

[Pistol1]

Unfortunately, that's not possible.

 

[Hugh Jaleak]

It would be beneficial long term to run separate wastes, there is always the danger that when emptying the bath, the contents will reappear in the shower.... Especially when the waste begins to clog up with hair and soap over time.

Went to look at a job recently, young couple bought their first house, she'd had a bath, pulled the plug and gone into the bedroom to dry her hair. He was below in the kitchen and got a recycled shower when the bath water erupted from the shower waste, filled the tray and overflowed into the bathroom..... I found the waste to be blocked almost solid!

 

[Pistol1]

Erk.

Unfortunately in this case, running a separate waste would require removing a slate roof. And that would be the easy bit...

I'll just have to be diligent about cleaning the waste pipes out!

 

[Hugh Jaleak]

Maybe wise to look at the possibility of adding a HepVo waste valve into the shower waste prior to the bath joining then. Will stop the siphoning issues, and may negate the need for an AAV on the waste. The HepVo also acts as a non return valve which may be useful in your situation!

 

[Pistol1]

Interesting. I will have to measure the fall on the pipework, though (Hepvo needs at least 10° it seems), and it's pretty tight against the wall and the floor - I don't know if the compression fittings on a hepvo would fit. I had planned on using a solvent welded tee for that reason. Suppose I can only check though!

 

[gigz]

Fit anti syphon traps to both the shower and bath, take the overflow pipe off the bath waste and wash or renew it, these harbour waste/dead tissue that stinks.

 

[polesapart]

Yes, putting in an AAV above height of bath spillover or at least above overflow height is good idea in this situation.