Thanks for your quick responses.
ProDave, The house is 24 yours old, and does have wall and floor insulation, but not much? I believe the wall insulation is about 12mm, or at least this is what I can see in the integral garage wall, and the floor insulation is only about 50mm. I do plan to try and run at a lower temperature 24/7, that way, if I get the temperature right, the floor will always be warm, as opposed to currently, where it switches off for periods when the rooms are warm enough, but I'm not sure what effect, if any, this will have on the condensing combi boiler if it is working most of the time?
The UFH is wet with 16mm pert-al-pert pipe, using a 7 port manifold, 3 zones downstairs, and 4 zones upstairs...I know I should have had a manifold on each floor, but I had no where to put one upstairs. All controlled by wireless thermostats.
SteamyTea, thank you for the info. The house doesn't usually get that cold, but it has always been heated in the past by traditional radiators. The only room that is not currently heating that well is the kitchen, but I guess this is down to the lack of floor space containing UFH, but having said that, it does contain an oven, so not too worried. Draught wise, it is not a draughty house, so I'm actually hoping for a cold winter, so I can properly test the system ?