How can I reconnect this apparently immovable overflow pipe to the cistern?

by | Apr 23, 2024

Questions › Category: Questions › How can I reconnect this apparently immovable overflow pipe to the cistern?
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Handyman Staff asked 7 months ago

1960s house in the UK, possibly original fixtures. We've redone one bathroom, the other is going to have to wait for a few months more, so I'm trying to make good some of the tired old fixtures until then.

The toilet cistern has an old-style overflow where an opening in the side of the tank drains into a pipe routed through the wall on to a roof pitch, rather than going into the pan as modern ones do. The float valve in the tank sometimes doesn't quite shut off (which the overflow is designed to deal with), but the plastic connector that joined this pipe to the cistern was leaking a little, and when I tightened it, it broke in various places.

I'm now trying to replace that connector. A few parameters:

  • The overflow pipe moves just a few mm in each direction. Let's assume for the time being that it's fixed in place, and I would rather not break it out of the wall and replace it unless I have to (it's routed through a roof tile and I'm sure it's fastened somewhere behind the tiles and I can't easily get at it).

  • If we were intending to keep these bathroom fixtures I would replace the fill valve with one that shut off properly and/or replace the flush with one with an integrated overflow. However it's likely that in a few months we'll replace this whole bathroom so I'm trying to fix what's there now if it can be done easily.

  • The overflow pipe has an outer diameter of about 22mm (I haven't found my calipers yet after the move, so used a tape measure as best I could). The end of the pipe is about 23mm from the outside wall of the cistern, and the cistern wall is about 8mm thick. The hole in the cistern measures approx 1"/25mm across.

Here's the setup:

Arrangement of pipe and cistern

Arrangement of pipe and cistern

Here are the remains of the original connector. Note, critically, that the threaded part was inserted into the cistern hole from inside the cistern, passing over the end of the pipe where a nut provided some compression.

Remains of original plastic connector

The first thing I tried was to buy a McAlpine R4M straight tank connector which has a backnut (on a 3/4" thread) to secure it in the tank hole and a compression fitting to connect to the pipe. However the threaded part must be inserted from the outside and there is no room to get it past the end of the pipe. The pipe wiggles a bit, but nowhere near enough. Even if this were possible, I'm not sure the insertion depth of the pipe would be enough to make a good connection. Here are the parts of that component, laid out in the direction they would be fitted:

Exploded arrangement of McAlpine R4M tank connector

I then bought a "35mm compression tank connector" similar to this one. This has the right compression fitting and it is meant to go into the hole from inside the tank, but the thread is too wide to get through the hole (I'm guessing it's a 1" BSP thread). And even if it did fit, I think it has the same "reach" problem to get to the pipe.

Brass 35mm compression connector

Here are some other ideas I haven't tried yet:

  • Cut the pipe down, use the space created to insert the McAlpine connector above, then use a 22mm push fit straight coupler (which I already own) to join up with the end of the pipe (re-using some of the cut-out section). However I'm not sure a push fit connection on both ends can be made successfully given the immovability of the pipe, and the push fit connector I have is quite long – maybe too long to be installed in the available space along with the McAlpine connector.

  • Buy a 15mm tank connector like this one, cut the 22mm pipe down a bit, push a piece of 15mm pipe all the way through it to the outside, and insert one end into the connector. However these connectors all seem to be designed for maximum tank wall thicknesses of 4mm (I guess plastic tanks) and most seem like they wouldn't be wide enough to fill the 1 inch cistern hole.

The main problem seems to be that in all my searching, I haven't found a compression fitting tank connector where the "compression" end is designed to be passed through the hole in the tank from the inside and on to the pipe.

So with all that said, are there any other ways or other combinations of components I could use to make this connection between the 1" overflow hole and the basically-immovable 22mm pipe? Is there a name for this apparently extinct original connector where the threaded part passed over the 22mm pipe? Any other ideas? Or do I need to face facts and plan to excavate that pipe and reinstall something more flexible or of more appropriate length? Thanks.