i would check viessmans aftersales service and "technical" helpline before you consider one of them. they are good boilers when they work, but just ring them yourself and see how long it takes to get through. almost as long as vaillaint id imagine. mind you i waited 6 hours for clyde combustion to ring me back today.
was told the price of the overheat stats was 90 quid each. when technician rang me to confirm this i was told "its cos they are auto reset stats" well thats great seeing as they interupt thermocouple voltage and kill pilot light. stat resets but who gets to relight pilot light?? needless to say - another boiler type we will rip out and replace with remeha who at least have the decency to apologise for boiler failures, answer the phone within 30 seconds and dont charge the earth for spares.
broagg for prime minister IMVHO.