Grohe Concealed cistern fault

[Sleebagz]

Hi all

I live in a 5 year old new build property with Grohe concealed cisterns on 3 separate toilets.

Over the last year or so the toilets have all started with the same fault - namely the toilet flushes as normal, then continues to flow into the bowl instead of refilling. A further press of the buttons on the flush plate solves the issue and the toilet refills as normal. Happens maybe 1 in 20 flushes, otherwise the toilets work as normal.

I’ve contacted Grohe, who were as useful as a chocolate fire guard, and I’ve also dismantled the cisterns and checked and cleaned all seals etc. Everything looks in good condition and appears to work as it should.

Just wondering if anyone has had a similar issue?

Grohe suggested replacing all the internal components, at a cost of £150 per toilet!! But seeing as though they couldn’t even tell me what they thought would be at fault I’m loathe to spend any money replacing parts that might not be faulty.

Any advise greatly appreciated. I’ve attached some photos of the components.

 

[jj4091]

I can only think of 2 comments.1) Are the cables from the push button to the valve sticking ( i presume they are like a push bike brake cable and may have rusted a little internally.
2) If you do decide to replace the valves then don't use Grohe again as it doesn't seem like they are fit for purpose.

 

[Sleebagz]

I can only think of 2 comments.1) Are the cables from the push button to the valve sticking ( i presume they are like a push bike brake cable and may have rusted a little internally.
2) If you do decide to replace the valves then don't use Grohe again as it doesn't seem like they are fit for purpose.

The buttons work on air via a tube. I’ve tried blowing down the tubes and they’re all clear, plus they work the flush when you blow down hard enough.

 

[kidgreen61]

I would replace the components, but use Grohe ones.
Similar components are readily available for a fraction of that price.

 

[Sleebagz]

I would replace the components, but use Grohe ones.
Similar components are readily available for a fraction of that price.

That was my intention, so I emailed a couple of websites such as bathroomspareparts and they all told me to use Grohe components as they are pretty specific for the Grohe frame.

Looks like I’ll have to replace the internals on all the toilets and hope it fixes the issue. 300 quid down the drain, literally, if it doesn’t

 

[kidgreen61]

Sorry, typo on my part, I meant don't use Grohe parts.

 

[Sleebagz]

Sorry, typo on my part, I meant don't use Grohe parts.

Any suggestions on alternatives?

 

[yorksbuilder]

look at Geberit

 

[Rodders53]

Usually it is the "rubber" valve at the bottom of the usually bayonet-fit flush valve that gets scaled up dirty and less flexible with age that needs replaced on a routine basis.

They don't fully / reliably seal and pass water into the pan.

Sometimes a clean up and a smear with silicone grease can work for a time - both the rubber washer and the seat of course (the latter will need cleaning if a new washer is fitted in any case).

My Siamp units need doing from time to time, as will Geberit replacements.

Genuine and pattern parts are not always a mile apart in price. Assuming Grohe flush valve washers are replaceable, of course!

 

[Sleebagz]

Usually it is the "rubber" valve at the bottom of the usually bayonet-fit flush valve that gets scaled up dirty and less flexible with age that needs replaced on a routine basis.

They don't fully / reliably seal and pass water into the pan.

Sometimes a clean up and a smear with silicone grease can work for a time - both the rubber washer and the seat of course (the latter will need cleaning if a new washer is fitted in any case).

My Siamp units need doing from time to time, as will Geberit replacements.

Genuine and pattern parts are not always a mile apart in price. Assuming Grohe flush valve washers are replaceable, of course!

This is what’s puzzling me as I’ve dismantled all internal components and all the seals are in good clean condition with no signs of wear. Plus the water doesn’t leak into the bowl at any time, other than when the fault happens, which is perhaps 1 in 10/20 flushes. A press of the flush buttons rectifies it and the toilet fills as normal. This is why I’m reluctant to replace all the internals like Grohe say, because I’m not entirely sure they’re at fault…!

Personally I think it could be the flush plate / valve itself, but Grohe technical department are adamant it isn’t .

 

[jj4091]

The diificulty you have is that it is so intermittent. If you wait until it is happening more frequently then perhaps you could put some marker dye in the cistern that will leave a stain where it is leaking. Or is there a way of adding some weight to the seal that would apply more downward pressure