While you wait for answers, we may have found some information which could help you.
Click here for Horstmann Channel Plus H 37 XlHorstmann Economy 7 problem?
setting clock of economy 7 horstmann boiler?
horstmann ChannelPlus H37XL?
horstmann economy 7 heaters not coming on?
Horstmann channelplus model H37 - ch won't come on?
horstmann channel plus h 37 xl?