Frequently asked questions (FAQ'S) about underfloor heating systems and our services. You will find most commonly asked questions here. Jun 10, 2016 My thermostatic bath mixer has started throwing out luke warm water on the hottest setting, I've been told its a pressure issue so I'm going to try and install a. Boilers for central heating, Potterton Boilers, Worcester Boilers, Ferroli Boilers, Biasi Boilers, Vailiant Boliers all available at plumbing world. Product Part number Type Fuel; Greenstar 28i Junior: Combi: Gas Greenstar 28: Combi: Gas User Manual. Log in or Sign up.