toilet not flushing

lightfoot · Apr 7, 2010

Fitted a brand new toilet last july on ground floor of house,and initially the new toilet would not flush so i assumed the diaphragm on the syphon was at fault, and changed it for another one. This is a close coupled toilet by the way. Again it would not flush so after a lot of head scratching i went out to investigate. Directly outside the other side of the wall to the toilet was a short vertical rise of soil pipe about a metre tall with a cap screwed on the top of it, and when i removed it i could feel a whoosh of air and see the water being taken away down the drain pipe. The toilet flushed like a dream after that. I screwed the cap back on and drilled a small hole thinking the problem was due to lack of ventilation.
Now months later the toilet wont flush again. Surely the diaphragm on the syphon couldnt be perished already. They have an upstairs toilet that wastes into a seperate soil stack, and this one flushes fine. There is no blockage on the problem toilet as it is not backing up. Any ideas?

WHPES · Apr 7, 2010

Take the soil stack above the eaves and leave open with a bird cowl on top, else an air admittance valve on the top of the short soil stack you describe.

lightfoot · Apr 7, 2010

Thks for getting back. i thought an air admittance valve was only meant for inside the house, and not outside. will try one anyway as i havent got the ladders to extend soil stack to the eaves as the house is a 3 storey mansion.

stevetheplumber · Apr 7, 2010

cant see how the soil stack can stop the flush do you men the pan wouldnt empty after flushing?

WHPES · Apr 7, 2010

AAV will work just as well outside but outside should have a full soil stack instead.

I assumed you meant the water won't go away. If it's the actual syphon and the water won't fill the bowl, ignore my suggestions. However the stack shouldn't just be capped off.