While you wait for answers, we may have found some information which could help you.
Click here for Heating Water ExactlyHorstmann channelplus model H37 - ch won't come on?
Standy by battery on Horstmann H37 XL Progammer?
setting clock of economy 7 horstmann boiler?
wiring horstmann centaurstat 7?
horstmann channel plus h 37 xl?
Whats wrong with my Vokera Mynute EHE boiler?