Hi We have a combi boiler that hasn't been used for 3 years. It is a Vaillant turbomax VUW 242 and has been stored in the house for 3 years but not connected. The boiler is probably about 12 years old. If professionally installed, would it still be OK to use after being left unused for this amount of time. Also, as the boiler hasn't been connected, the radiators haven't been used either - should these be OK or is there a possibility that they could have corroded. Thanks.