Boiler keeps firing up

[hjimbob]

I have an Ideal boiler (ancient) with a Honeywell ST9420c control and one thermostat. I believe it is an S type system from what I have read.
I changed the control from an old Honeywell a month or so ago. The system seemed to be running as expected.
Now, the system keeps running when I don't expect it to. When the control isn't 'asking' it to run.
I've attached the airing cupboard. Well, a picture at least.
The Grundfos pump seems to be kicking in when I expect it to be off.
Any help identifying the issue would be greatly appreciated. My gas bill is getting a bit extravagant!

 

[Exedon]

Motorised valve micro switch stuck favourite
If your competent with mains voltage and have a multimeter check if orange feed from Motorised valve live.
Assuming it's wired correctly !.

 

[CountryFan]

Hard to tell but looks like a y-plan. As above either stuck micro switch or incorrectly wired

 

[hjimbob]

Thanks. Am I right in assuming that, as there is no hot water when the problem occurs, it is the micro switch on the CH?

I thought it was S plan like the diagram attached as there are 2 no. 2 port valves.