Concealed cisterns with bigger non equal flushpipes

[WaterTight]

Ones where the drop valve end of flushpipe is bigger and pan end of flushpipe bit smaller and a smooth circular nut is found on flush pipe under cistern. Does anyone know if there is a universal 2" valve that will work in these? And seal properly to existing cistern/flushpipe?

Also is the end of the flush pipe standard 1.5" where it enters pan so failing that you could change cistern and flush pipe to a fluidmaster or similar? Thanks

 

[Riley]

My merchant always holds replacements so I assume that most good ones would

 

[Shower Engineer]

Sounds like a Grohe Dal cistern although others may be similiar.
If it is Grohe Dal then nothing else but original parts will fit, they are all available here dal cistern | eBay The flushpipe is 50mm x 40mm if that helps.
Dave

 

[WaterTight]

Thanks Shower Engineer. I've seen one before that is def that one.

I saw another today and am not sure. It looks like someone had stuck a Wirquin in it and it was leaking from under the cistern. But correct me if I'm wrong, the Grohe ones seem to have the thread that joins to the flushpipe nut as part of the underside of the cistern, actually joined to it. So if it were to leak it would only leak down flushpipe, rather than across underside of cistern. So probably not a Grohe.

As the flush pipe is 40mm at the pan end, if there was room (length in the horizontal section,) I guess you could use a 40mm to 32mm reducing mcalpine multifit compression coupler and convert to a regular flush pipe and cistern?

 

[WaterTight]

Corr what a merrygoround this stuff can be.

 

[Shower Engineer]

I saw another today and am not sure. It looks like someone had stuck a Wirquin in it and it was leaking from under the cistern. But correct me if I'm wrong, the Grohe ones seem to have the thread that joins to the flushpipe nut as part of the underside of the cistern, actually joined to it. So if it were to leak it would only leak down flushpipe, rather than across underside of cistern. So probably not a Grohe.

It is not possible to fit anything but a Grohe valve in a Grohe cistern and you are right the only place it can leak is the flushpipe nut, actually it is a very good design in that respect.
If you have a photo of the valve I can probably tell you what part you need.
You could change the complete cistern but you would need a new flushpipe and pan insert as well.
Dave