I am having a real problem with a leak that commenced a couple of months back re my folk’s WC. It is a straightforward Armitage Shanks low-level type (relatively old) that started leaking underneath the WC from the siphon connection. I took the thing apart and it appeared that the siphon sealing washer had become rather brittle over time. When reassembling with a new washer it became clear that the outlet on the cistern is substantially larger (58mm diameter) than the diameter of the siphon’s threaded tail (45mm diameter). Just about all similar cisterns that I have dealt with previously have a more snug fit with siphon.
Despite several attempts I could not get the connection to seal though I was not surprised given the gap between the threaded section and the cistern outlet. What was more bemusing was how the original connection had ever held in the first place. Anyway I chose to fill the gap with a roll of Plumbers’ Mait and reconnect. This sealed the connection perfectly fine. I checked this over the next couple of days to find that it was completely dry.
A couple of weeks later I received a call from the folks to say that there had been a substantial leak from cistern and he had turned off the service valve and sponged out the cistern. This left him having to use a bucket until I could return – not a total crisis as this is a second WC in the folk’s home.
So upon engaging with the WC once again I checked out the connection and removed the PM from the failed joint. I had brought a couple of alternative siphons and several different washer types. One thing I noticed was that the flange area of the fitted siphon was slightly smaller than that on the other siphons. So I decided to change this for a wider flanged Dudley 2-piece. Among my alternative washers I had what I refer to as a ‘throated washer’ which rather bulkier than the standard sealing washer but managed to seal the said area nicely.
I reassembled and tightened the backing-nut on the joint by hand and reconnected the flushpipe. I then filled the WC and gave it a flush. A little water penetrated from the joint but I tightened this gently with a wide-jawed spanner. The joint remained dry and could be flushed without problem. This successful state of affairs seemed to continue for a couple of days but weirdly the leak infuriatingly returned. A further gentle nip with the spanner prevents the leak for a while but at some stage it reappears.
Does anyone have any ideas as to what I could do here, please? Maybe it would be worth running a few layers of PTFE around the siphon thread? If nothing else works then I reckon I may have to use silicone to make the seal but that is a bit 'last ditch'.
Also why do the siphon manufacturers cut away a section of the circular flange? Though I have never had a problem with fitting siphons previously it does seem likely to minimise the sealing area twist siphon and cistern?
Note: The photograph is a slightly larger version of the washer that has been fitted.
Despite several attempts I could not get the connection to seal though I was not surprised given the gap between the threaded section and the cistern outlet. What was more bemusing was how the original connection had ever held in the first place. Anyway I chose to fill the gap with a roll of Plumbers’ Mait and reconnect. This sealed the connection perfectly fine. I checked this over the next couple of days to find that it was completely dry.
A couple of weeks later I received a call from the folks to say that there had been a substantial leak from cistern and he had turned off the service valve and sponged out the cistern. This left him having to use a bucket until I could return – not a total crisis as this is a second WC in the folk’s home.
So upon engaging with the WC once again I checked out the connection and removed the PM from the failed joint. I had brought a couple of alternative siphons and several different washer types. One thing I noticed was that the flange area of the fitted siphon was slightly smaller than that on the other siphons. So I decided to change this for a wider flanged Dudley 2-piece. Among my alternative washers I had what I refer to as a ‘throated washer’ which rather bulkier than the standard sealing washer but managed to seal the said area nicely.
I reassembled and tightened the backing-nut on the joint by hand and reconnected the flushpipe. I then filled the WC and gave it a flush. A little water penetrated from the joint but I tightened this gently with a wide-jawed spanner. The joint remained dry and could be flushed without problem. This successful state of affairs seemed to continue for a couple of days but weirdly the leak infuriatingly returned. A further gentle nip with the spanner prevents the leak for a while but at some stage it reappears.
Does anyone have any ideas as to what I could do here, please? Maybe it would be worth running a few layers of PTFE around the siphon thread? If nothing else works then I reckon I may have to use silicone to make the seal but that is a bit 'last ditch'.
Also why do the siphon manufacturers cut away a section of the circular flange? Though I have never had a problem with fitting siphons previously it does seem likely to minimise the sealing area twist siphon and cistern?
Note: The photograph is a slightly larger version of the washer that has been fitted.
