A bath shower mixer tap looks like a simple swap, but whether it works depends on pressure and flow, not the boiler badge. This guide explains the 0.2 bar minimum listed for the Aqualisa Central, Uptown and Downtown taps, how much head a loft tank really gives you, and why a combi is limited by heat output rather than the tap. It also covers the hose rule that keeps a handset clear of bath water, with prices and stock checked on 4 November 2026.