Hi Guys and Gals, Overview of the issue Biasi Advance 30S combi boiler installed for around 15 months. Hot water working fine heating was fine. Heating stopped working but boiler did not display error. I am an electrician so immediately started to fault find. Though it was a faulty stat so I removed the stat and hard wired the remote stat connections within the boiler. Still no heating. Tried manual override on boiler on the controls interface to force heating on. Heating will not come on. I can adjust the heating set point and can read the current LTHW temperature recorded the boiler so all seems fine. No error codes are displayed. Hot water still working fine. It is almost as though the summer mode was on (which is was not). Having reviewed the wiring manuals I then tried something a little off the wall. I wired the external stat to the boiler external frost stat input. Boiler fired up and works fine however the frost protection sequence only allows the boiler to heat up to 50 deg C. Clearly there is still an issue with the boiler which I need to resolve. I wondered if there was a difference firing sequence in frost protection to normal operation that would allow me to pin point the issue. Spoke to Biasi – not interested, out of 12 month warranty. Didn’t really understand my issue and Engineer visit required at absorbent cost. Backstop is always that the PCB is defunct but I’m keen to check other options before simply swapping this out on a wing and a prayer. Any thoughts welcome.