Advice on hot water system

[stevo1_l]

Hello,

I had the hot water tank replaced yesterday as the old one had split. The new installation was finished but last night when the water heating control kicked in so did the central heating and the radiators hotted up. I spotted on the diverter valve that there is a setting to switch from manual (open) to Automatic. This seemed to do the trick and stopped the radiators heating up but I'm adamant the central heating pump is running as I can hear it and it's vibrating. I've attached some pictures of the setup just for clarification on the valve and pump.
Thanks

 

[ShaunCorbs]

Was it in the locked open position they might if forgot to slide it back once they’ve filled the heating system