1- If your heating system is a closed circuit (wall-hung boiler):
First, turn off the central heating system (the wall-hung boiler), then release the trapped air through the air bleed valve at the end of each radiator. fill the wall-hung boiler through the water filling valve that is embedded at the bottom of the device. the water pressure level must be between 1 to 1.5 bar. turn on the device now.
2- If your radiator system is open circuit (central boiler room):
First, turn off the circulating pump (located in the central boiler room). after a few minutes, release the trapped air through the air bleed valve at the end of each radiator. Finally, turn on the circulating pump.