New push button valve - different outlet size

[IT Minion]

My push button toilet (concealed cistern with a good distance to pan) has been leaking and I've got a replacement valve for it.

However the new valve has a smaller outlet pipe size than my old valve, so the existing flush pipe can't fit inside and there's no way to connect it with my current bits. I'm not sure what the best option to sort this is.

Can I get a converter to step the flush valve up to fit the existing pipework?

Do I need to replace the existing flush valve with a smaller diameter pipe?

Have I bought the wrong flush unit?

New valve on left, old on right.

The new valve outlet is almost the same diameter as the approx 50mm OD flush pipe.

New valve:

https://www.screwfix.com/p/fluidmaster-push-button-cable-dual-flush-valve/51173?ref=SFAppShare

Can anyone point out the (probably obvious) best solution here?

 

[terryplumb]

Your old valve must have had a connector that joined the flush pipe to the valve ,which would be a reducer of some description. Show us a picture of that .
You have bought the wrong flush valve.
To use the new one you would need a suitable seal and compression nut that is the same thread as the flush valve thread.
There would also need to be some clearance inside ,between the flush pipe outer diameter and the inner diameter of the valve for a seal to fit .

 

[IT Minion]

Your old valve must have had a connector that joined the flush pipe to the valve ,which would be a reducer of some description. Show us a picture of that .
You have bought the wrong flush valve.

I think you're right on the wrong valve, but no reducer, just a simple rubber washer and nut.

Back to Screwfix for me.

 

[terryplumb]

Show us a pic of the "simple rubber washer"and nut.
I edited my previous post ,you may not have seen it.

 

[IT Minion]

This looks like a good replacement for me, although it references ceramic cistern rather than concealed plastic it shouldn't matter for just replacing the flush valve?

https://www.screwfix.com/p/flomasta-bottom-entry-flush-valve-pack/328jn?ref=SFAppShare

Old valve and related bits as requested.

 

[terryplumb]

Thanks ,so your flush pipe is a greater diameter at one end , and thinner where it goes into the toilet pan ?
Your original pic of it didn't appear to be ?
I can't open the link ,Screwfix site appears to be down.

 

[IT Minion]

No, it's a consistent 50mm OD from cistern to pan.

 

[IT Minion]

Appreciate the help on this by the way, any thoughts on the latest Screwfix link for suitability? I don't need the fill valve just the flush.

 

[terryplumb]

When I click on that link it comes up with Screwfix is having technical issues. You need a flush valve with 2 inch tail ,not one that can be used for 1 ¹/² inch and 2 inch ( they are the same as you already have ,and no use )
Unfortunately the manufacturers of most of these 2 inch flush valves do not include the seal and nut to connect to your flush pipe ,so the ones from the original ( as you pictured) must be compatible with the new valve that you buy. Take them with you to try on the new valve.

 

[IT Minion]

Product code 328JN.

 

[terryplumb]

Will take a look

 

[terryplumb]

Yes that flush valve is the type you need.
Take your seal and nut with you to ensure the threads are compatible,and seal fits.

 

[IT Minion]

Yes that flush valve is the type you need.
Take your seal and nut with you to ensure the threads are compatible,and seal fits.

Done, fitted and not leaking so far. Thanks for the help.

Now to see if I can manage a siphon toilet all by myself....

 

[terryplumb]

Why are you changing the said siphon ? They are usually more reliable than drop valves.

 

[IT Minion]

It was also leaking/running constantly. I've no idea why but there was a little bit of corrosion in and around the coupling plate, I don't know if that could have compromised the donut or the seal above.

I've cleaned and installed a new siphon, donut and coupling plate and it seems, so far, to not be leaking. Even if it weren't the siphon I might have fixed it by accident.