Repair or replace concealed WC cistern?

[Cambridge Mum]

I've looked back through the threads but haven't been able to find a clear solution.

Installed in 2008 I have a Macdee concealed cistern (maybe a PNEU COMPACT II with a Kayla mechanism?) behind a slimline WC unit made by Utopia for Nabis. The WC unit is only 220mm deep and 500mm wide. I think the water comes in from the bottom and limited access can be obtained through the front. On top of the unit is a worktop that also connects to the next unit where there is a set in wash basin. So I really don't want to have to take the worktop off, as this would also mean disconnecting the plumbing to the basin and then refitting it, which would make the job quite a bit more expensive, I guess.
I am getting a plumber in to sort things out, so I really would like to solve this so that I don't have a problem again for as long as possible.

The flush mechanism has played up for a long time and today it started to send water into the bowl all the time after a flush, so the cistern never filled up and water was running into the bowl for hours. Eventually I got the front off and found before me the white flush valve labelled Macdee, into which a pipe connects to the flush button on the front panel. On the right of the cistern is a blue and white component. I found if I lifted something at the top of the right hand blue and white component that the dribbling into the pan stopped. When I let go, it started again. At the moment I am keeping it a bit elevated by wedging the end of a screwdriver in place, so the water flow has stopped.

The inside of the cistern is pretty filthy and there is also scale.

Is it likely the plumber needs to take out the cistern and give everything a good clean as well as replacing any problem parts? And would he have to disconnect the WC and take out the whole of the WC unit in order to do this? I assume yes?

In which case, would it make more sense to have a new cistern fitted with better quality innards? If so, which brand would you recommend, please? Is there one that is much better than the others?

I understand that Utopia use Thomas Dudley Vantage in their own units.
Nabis apparently doesn't use Macdee (Kayla?) any more but uses Wirquin.

Roper Rhodes have their own brand dual flush concealed cistern, which can be purchased as a separate part.

I wondered about Grohe and Gerberit, but know nothing about them.
I read the recommendation to use a Flindmeister inlet valve on another thread but followed up the lead and couldn't work out which part was relevant. Also is it the inlet valve or the other part that's defective?

 

[Blagard]

If the WC pan has water pouring in immediately after flushing then the Flush valve will be the problem. (This is what you have described)

If the water stops flowing for a minute or two before starting again then it is likely to be the fill valve (float valve).

In either instance access into the top of the cistern will be required to service the offending part.

Lifting the float valve has the same effect as a full cistern and it will shut off the water and so stop your water loss.

It is possible you may be able to remove the upper part of the flush valve to clean the seal and seal seat. I would try that first anyway. Most flush valves are connected to the lower part by a bayonet type fixing so twisting to disconnect them may be all then is required You could simply have some loose lime scale obstructing the seal!

To completely replace a flush valve you need access to the underside of the cistern to disconnect the flush pipe and enough space at the top to get the parts in and hold them in place with your arm. So fetching the top off may not be required. It may not be necessary to remove the pan. It all depends on the access the removable front gives.

Photo's would be good idea if you are thinking of tackling it yourself.

 

[Cambridge Mum]

Typo in last paragraph : it should read Fluidmaster.

 

[Cambridge Mum]

Thank you, Blagard. What has been happening is the first scenario you described. It's demoralising that the worktop will have to be removed to service the cistern, even though there is front access. In that situation, I think I shall replace the whole thing, as I am paying a plumber in any event, and even with a new cistern and push button, labour costs are likely to be the main cost of the job. I think I shall go for a Thomas Dudley cistern unless my plumber says there's a very good reason not to.