We have a vented Vaillant Ecotec 630 with a 300L tank, 7 rads using 22mm backbone and 15mm tails and hot water.
Have just had UFH installed downstairs which is a 9 port manifold with pump - this is made up of
3No Lounge - 1 Zone
3No Kitchen - 1 Zone
1No Hallway - 1 Zone
1No Study - 1 Zone
1No...