Hi,
My 5 year old house (built by a major company) has a "conventional" hot water/heating system:
Gas Boiler (Potterton?)
Siemens programmer
Pre insulated Hot water Tank (in airing cupboard)
Siemens DVA3 actuator
Siemens 22mm 3 port Valve.
Inhibitor in system.
The problems I have had...