Does your system have 2 2-port motorised valves (usually silver cased)?? If not, and only had 1 3 port motorised valve (illegal with an megaflow to have just 1 of them) then the stat could have failed. If you do have 2 2 port valves, have you manually push the leer across on the hot water...
Does anyone know any good heat loss / radiator sizing / boiler sizing calculations? There are many ways to do this, including a written calculation, but they are vary and offer different answers! :(
For those that have done this before, and in your opinions, what are the best ways to...