Is My Thermostat Broken?

Reed_Richards

I think you might be better-off posting this query to a plumbing forum.  Or paying for a "service" on your heating system.  

btr30

if if you turn thermostat up until it clicks, during an on period as set on programmer, and valve opens and boiler starts then thermostat is doing its job. If heating is not delivered to area required there may be an issue with TRV stuck closed air or sludge in system, defective pump. It is a case of eliminating potential causes.
if thermostat clicking doesn’t bring on boiler then you have a fault with thermostat or heating valve end switch