Water level in toilet pan drops

[clivediyer]

Hi Guys,
We live in a 4year old, 3 floor town house with a toilet on each floor (very useful when you reach a certain age!). Recently I have noticed that the water level in the toilet pan drops by 50-75mm soon after flushing. The flush works well with no rise of level in the pan which might indicate a blockage.
Has anybody any ideas

 

[Resolute]

Does it do this on all the toilets?

 

[clivediyer]

No just the middle one

 

[Resolute]

Are they all linked to the same soil stack? How about the other traps on the sink, basin, bath etc? Also, is it a standard pan or a syphonic? And does there seem any problem in flushing the waste away (i.e. fills particularly high before disapearing)?

 

[clivediyer]

Hi Resolute
The top and middle floors are linked to the same stack. The other traps seem to be OK (no smells). It is a close coupled pan. I had thought perhaps agood plunging would help?
Thanks for your interest
Clivediyer

 

[kay-jay]

does it happen when you flush the middle one? or does the middle one level drop only when you flush the top floor one.

sounds like the water from the upper floor bog is syphoning the trap from the middle bog as it runs full bore in the pipe past the middle floor branch.

has this problem always existed or just started??? check operation of aav if there is one. or fit a branch ventilation system to break the vacuum


KJ

 

[double d]

Ye sounds to me that theres a bit of self siphonage there :0

 

[Tony@ Studor]

Sounds like self siphonage, suggest installing an AAV on branch line by W/C, could be on the basin run if it connects to 110mm before main stack.