Civil Engineering Reference
In-Depth Information
hot water reheat coils or electrical strips that are designed for either heating or
dehumidifi cation of the air).
The sources of energy consumption in this type of systems are air handling unit
supply fan motor input power, return/exhaust fan motor input power, hot water
pumps or electric preheat coil (if it is used for freeze protection instead of hot water
coil) in air handling unit and hot water pumps or electric reheat (if it is used for
dehumidifi cation or heating instead of hot water coil). Duct air leakage, heat trans-
fer from ducts, and effi ciency loss in water coils are other sources that can indirectly
increase the energy consumption of the system. The small energy consumed by the
low-voltage power provided for control valves and dampers is the other source of
energy consumption.
8.12.4
Variable Air Volume System with Parallel Fan
Powered Units
This system (Fig.
8.7
) is consisted of a central, variable volume supply fan that
supplies conditioned air to all the local parallel fan-powered variable air volume
terminal units through a network of medium pressure supply ducts. Quantity and
temperature of the mixture of the air which is delivered to each room is designed
based on the room sensible load, the quantity and temperature of the outdoor air in
Fig. 8.7
Variable air volume system with parallel fan powered units
