While you wait for answers, we may have found some information which could help you.
Click here for Displaying Time BoilerStandy by battery on Horstmann H37 XL Progammer?
Horstmann channel plus. The water is on all the time?
horstmann channel plus h 37 xl?
wiring horstmann centaurstat 7?
Horstmann Economy 7 problem?
Whats wrong with my Vokera Mynute EHE boiler?