High-Static Ducted Fan Coil Units

High-static ducted fan coil units are intended for projects where conditioned air must travel through a longer or more resistive duct network. The unit is concealed above a ceiling or inside a technical area, while ducts distribute air to several diffusers. Their main difference from low-static ducted fan coils is the higher external pressure available from the fan. This makes them relevant to office floors, restaurants, retail premises, hotels and other commercial zones requiring planned air distribution.

The Midea MKT3H range includes 70 Pa and 100 Pa external-static-pressure classes. A 70 Pa model may suit medium-length layouts with several outlets, while 100 Pa versions can be considered where higher airflow and greater system resistance are expected. Size classes extend from approximately 800 to 2200 CFM. These values guide initial selection, but the actual duty point must be checked against the calculated pressure loss of the complete duct system.

Higher static pressure does not automatically mean a better or quieter selection. Excess available pressure can increase air velocity, sound and electrical consumption, while insufficient pressure can leave remote diffusers short of air. Duct length, cross-section, bends, dampers, filters, grilles and diffusers must be included in the resistance calculation. The fan coil should then be selected at the required airflow and external-pressure duty point.

The casing should be installed level on vibration-controlled supports, with a flexible connection between the unit and ductwork. Chilled-water pipes, valves and the condensate line need complete insulation. The drain should have the correct fall, an appropriate venting arrangement and a service point for cleaning. Access to the fan motor, filter, heat exchanger and electrical box must remain open, while duct joints should be sealed to limit air leakage.

For shorter, lower-resistance networks, review the ducted fan coil units category. Other room-terminal formats are listed under fan coil systems. A high-static model should be selected from the cooling and heating load, project airflow and the pressure calculation of the entire duct network.