Toilet Venting issue i think ?? help?

[furrywall]

the house; 3 toilets, 2 upstairs (both fine) 1 downstairs (the bad one).

downstairs toilet connected to horizontal waste all the way through the house to the vertical. toilet backs up right to brim (no blockage found).

i think its a venting issue as when the toilet backs up if you push the waste pipe opening up the rubber seal letting air flow it drains perfect so this leads me to believe there is a pressure wall infront of the slug as releasing the seal equalises the pressure solving the issue.

Question how can i test the vent?

according to my sister (her house) this happens every 4-6 months and they normally leave it to fix itself sometimes taking months

any extra insight would be appreciated

Kurt

 

[Hugh Jaleak]

Is there a decent fall on the horizontal section?

 

[furrywall]

Can't see the drop as waste comes off toilet into downward u bend and into horizontal under the floor. I cant take the floor up as when house was built they were morons and used huge floor panels instead of floor boards so to get under I would have to remove entire bathroom, laminate floor and skirting boards .

 

[yodaveg]

If your toilet drains when you make an air gap may be you could fit a pan connector with a boss on like this..

http://www.multikwik.com/product/39/130/90-bend-incl-40mm-compression-boss.html

then fit a small Air admittance valve on to it like this..

http://www.screwfix.com/p/floplast-...g & plumbing&gclid=CL6rl-6z5qwCFQUhtAod6S3JNg

on top or to the side. Should allow some air flow in and keep the smells out.
Ideally the air admittance valve should be fitted at a point higher than the cistern, but I have put them in lower occasionally.

 

[furrywall]

That is what i was thinking , didn't know you could actually get those.

is there any way to test if it is the vent thats the problem before i do change it?

 

[yodaveg]

I think you already have by allowing the air in to the wast pipe the blockage drains away. The vent pipe should really come off the system that is furthest away from the main drain outside the house, to avoid your issue.

 

[cantaloup63]

A short length of hose placed down the pan to the far end of the trap should give you the equivalent effect, for testing purposes.

Flush the upstairs pan to get the backing up effect then blow through the hose (in case it has kinked) to get a bit of air through. If this has the effect then it's a safe assumption to go ahead as planned.

 

[yodaveg]

A short length of hose placed down the pan to the far end of the trap should give you the equivalent effect, for testing purposes.

Flush the upstairs pan to get the backing up effect then blow through the hose (in case it has kinked) to get a bit of air through. If this has the effect then it's a safe assumption to go ahead as planned.

Like it, wouldnt have thought of that.