Duravit Cistern Puravida White Concealed Back Supply Df 0872700005 "upstair" Questions

when adding a new upstairs bath can I connect into stack vent or do I have to add from first floor main You can connect to the main stack coming from the main floor. You must however install a vent to

...on the model downstairs the water fills from the bottom of the valve and makes no noise, the one upstair used to do the same but now when it fills it makes a noise and the water fills from the top ...