Hi all hope you can help me on this one as heating is not my forteit. Got a communal heating system 6 flats one heating system. 5 flats have heat 1 doesn't. Plumber been to it and says its electrical as no power to the controller. Each flat has it's own controller fed locally from their own board. Each flat has it's own port valve in the plant room boiler and stats etc. There is also a bank of relays but not dont know what they do.Any help will be helpful guys