Method for tuning a ventilation system

摘要

The method comprises the steps of selecting the branch with the greatest pressure loss, opening the control valve in said selected branch and closing the control valves in all other branches, controlling the ventilation fan to produce the desired air flow rate into said selected branch by using fan characteristic shaft power to air flow rate curves, a shaft power estimate from the frequency converter and by adjusting the rotational speed of the electric motor with the frequency converter so that the desired air flow rate is achieved, calculating simultaneously the fan pressure corresponding to the desired air flow rate from fan characteristic fan pressure to air flow rate curves based on the desired air flow rate and the rotational speed of the electric motor, and saving the calculated fan pressure in the frequency converter as a reference pressure for the next step, adjusting the control valves in each of the remaining branches one-by-one so that the desired air flow rate to each branch is delivered while the fan is controlled by the frequency converter to produce constantly the reference pressure.