No heating! Honeywell cylinder stat not responding, this video will help, easy to follow. The cylinder stat is normally very reliable but can go faulty... | By Mr Combi.tm. Sales | Facebook
Honeywell L641A Hot Water Cylinder Thermostat
Cylinder stat operation - YouTube
C-plan with programmable thermostat? | DIYnot Forums
Honeywell evohome Hot Water Kit (RF Cylinder Stat, Sensor, Relay etc.) - PHC Parts