Recent content by sgdiy

Sorry to be naive but do I have to take the unit out from the wall to test it ... now sure how to take it out from the wall

Hi, My honeywell ST9100A programmer has gone completely blank after I went on holidays and switched off the boiler, no lights, no display The keston C36 combi boiler seems to be working fine and the hot water is still working. Any help to troubleshoot the issue will be appreciated.