Valve adjustment
In Velco valves, there is a self-contained thermostat that adjusts the valve opening according to the outdoor temperature. Upon delivery, the valve is in the factory default setting. In the factory default setting, the valve disc is fully open at an outdoor temperature of +10 °C and closes as the temperature drops to -5 °C. To ensure continuous ventilation, adjust the plate during installation to prevent it from fully closing when the temperature falls below -5 °C. The minimum valve opening can be adjusted as needed. For instance, in a building without mechanical exhaust ventilation, it is recommended to turn the valve disc one full rotation counterclockwise from the click position.
The plate is in the factory default setting when you hear a click while turning it.
When the plate clicks, turn the plate at least half a turn counterclockwise to open it.
After turning the plate half a turn, the valve will not close as the temperature decreases but will remain slightly open by approximately 2mm.