Torbeck Bottom Entry Filling Valve - Adjustable Height

Product Information

Am I right in saying these types of fill valve won't work on such low water pressure? I have removed the flow restrictor which the instructions say to do for water pressure below 1 bar. The old toilet was filled with water from the cold water header tank, and as that header tank is on a stand above the hot water cylinder in the adjacent airing cupboard, the water pressure is extremely low, about 5ft of head. A cookie set by YouTube to measure bandwidth that determines whether the user gets the new or old player interface.

The problem is firstly the fill is extremely slow (much slower than the old toilets fill valve, which was already pretty slow), but when full it does not shut off, in spite of the float floating up as far as it can. I'm re fitting a new bathroom in a flat. Trying to use as much of the existing plumbing as possible, and I have encountered a problem with the toilet fill valve. This cookie, set by YouTube, registers a unique ID to store data on what videos from YouTube the user has seen.

Product Specification

If this is the wrong type of valve for this application, what can I use instead. I really can't see that there is enough room in the small cistern for a conventional float valve.