Large bore kitchen mixer tap

Think by nature all monoblock taps use tiny feed pipes.

And How much effect will 20cm of narrow bore pipe have on the flow compared with the probable 10m plus of 15mm pipe in the feed.

Judging by my friend’s piss poor flow from his gravity fed system through a one hole mixer, I’d say a lot.

Tim

Not sure what sort of tap you are looking for but

might help. They all claim to be suitable for low pressure systems.

We fitted one of these:

because it was suitable for a gravity fed system. The hot is fed from a tank in the loft (via a cylinder) and although the flow isn't anything like mains pressure it is at least usable.

All monobloc taps have that restriction by default taps that are old fashioned have full turn handles (hot /cold) will flow more water than1/4turn or single lever. Failing that it will need a pump.

Has he got the correct tap though? Many are only for mains fed systems, but some, like our kitchen tap, are designed for gravity fed and a minimum head of 0.3 bar (so less than 10 feet). Our bathroom tap is rated for down to 0.1 bar and works fine, with the tank in the loft just over 6 feet above.

A great deal, by my own experience. But that could also be down to the internals of the tap itself. It's not likely a problem with a wash hand basin, but is with a kitchen sink.

The tap currently installed is the Franke Danube (now discontinued) I believe the minimum bar is .5

Exactly - the narrow bore pipe feeding the tap itself isnt the problem, but the internals such as filters aerators etc are !