Too little water from the flush tank or bad toilet?

Which model is the WC?

Seriously... the toilet doesn't fit the cistern. It just needs more power. Harshly said, since Geberit cisterns are nothing exotic, the toilet was probably, as you yourself already fear, a bad purchase. Ebay classifieds....Karsten

Unfortunately, I was mistaken in the opening post - we connected the toilet to the OMEGA UP cistern. I hung the bowl on a SIGMA cistern yesterday, and it works much better there. The two cisterns have about a 30 cm height difference and accordingly a completely different water pressure.

I then tried to get a reasonable answer regarding "compatible" bowls - unfortunately no one can provide a usable answer here. I actually only hear "The bowls always fit." The only technical information I find is about the maximum water volume - for the bowl purchased, that was 6 liters. The Omega cistern delivers that too - just like the Sigma cistern - but with the latter it works much better.

How can I tell now if a bowl fits a cistern?

Unfortunately, I also can't find the slightest information at Geberit about how, for example, to adjust the flush valve of the cistern. According to the diagram, several levels can apparently be set for the dual-flush, but the drawing doesn't make any sense to me at all.

What model is the WC?

OBI own brand wall WC rimless 145€ - that might invite ridicule, but I actually assume that the product "toilet" after about 100 years is nothing special anymore. I have no problem buying another bowl (OBI announced they will take the bowl back) - I just want to know which one.

Does your cistern not have a replaceable restrictor in the outlet? You would have to go for a larger one, if possible. We have TeCe, there are 4 different restrictors.

If only I knew... No info to be found on that. We have Geberit duofix sigma and Omega

He doesn’t say anything at all... he had the wall-hung toilet for 460€ and the lid for 247€ offered, so we decided to do everything in front of the wall ourselves.

oh SOOOOOOOOOOOO, WELL THENNNNNNNNNNNN

this is what happens when you do everything alone^^ Now I’m curious about the counterarguments again

oh SOOOOOOOOOOOO, WELL THENNNNNNNNNNNN

this is what happens when you do everything alone^^ Now I'm curious again about the counterarguments

Then I'll make my first post here. I'm not building new, but renovating my wife's parents' house. Some of it was done by companies, other parts I am doing myself. For example, the main bathroom downstairs was done by a familiar craftsman, who brought in a plumber. I am doing the small guest bathroom upstairs myself including the wall frame element (Geberit Sigma) and further installation.

This is now completed and although I am basically a desk person, I can say that it is not rocket science. On my Geberit Sigma is a Villeroy & Boch Architectura rimless toilet and it works perfectly. I would most likely suspect a problem with the toilet that maybe doesn't "direct" the water properly.

So you shouldn't always immediately say everything is bad just because it was done by yourself. He didn't accuse the plumber of installing the concealed cistern incorrectly or anything like that.