Joule Modul Air fault codes

10 codes from the Joule manual for the Modul Air heat pump. Pick one for what it means, the likely causes and where to start.

Code	What it means
12	No communication with the room thermostat
13	No communication with the boiler
20	Filter reached end of lifespan
30	Top tank temperature sensor error
31	Bottom tank temperature sensor error
32	Back up heater water heater temperature sensor error
35	Airflow sensor error - green comfort module
71	Over-temperature flow protection triggered
80	No temperature difference across the condenser
95	Water pressure is critically low (< 0.3 bar)