Air flow rate at every duct can be adjusted via flow control valves.
Waste air is removed through alleyways and stairways and is partly mixed with fresh air. The best combination of fresh air and recirculated is 50/50%. But waste air from galley and sanitary areas is remover separately by individual exhaust fans.
Fan coil units are based on the principle of decentralization of the air conditioning. A fan coil unit is provided in each room that can heat and cool the air locally. These units are necessary to install in those areas where additional cooling is required like telecommunication rooms, bridge, and switchboard room. Often these units are fed through the main Freon gas line, thus doesn’t require separate condenser.
Some hints on A/C system operation
It is advisory to clean condensers regularly depending on unit running parameters or time schedule. It’s practically to keep one condenser clean and empty with shut valves on stand-by. Too high delivery pressure (HP) is an indication of blocked condenser.
Low Side Refrigerant Charging
Low side charging is also referred to as vapor charging – that is we allow ONLY refrigerant vapor or gas to enter the system.
This is an easy but time consuming method of system charging. The canister supplying refrigerant is connected to the gauge service port and opened, and the HVAC equipment or appliance is run (which pumps refrigerant gas from the supply source in parallel with pumping from the outlet of the evaporator coil).
The refrigerant canister is kept upright so that only gas leaves the canister.
For me it is most precise method of filling a Freon gas, as you can control running parameters during charge and prevent potential over or under charge.