Product data

16 Catalog 724-2
Unit Selection
Unit Selection
To achieve an efcient fan coil system, accurate system
design and proper equipment selection is necessary.
Variations, limitations/control of fan coil systems, design
conditions and design load calculations are not described in
detail in this catalog. More detailed information may be found
in the ASHRAE Guide. This catalog contains ARI-certied
ratings and application ratings for ThinLine fan coil units
from which a design engineer can make initial unit selections
to meet system requirements.
A mechanical system designer must select the unit types best
suited to the overall system before the actual unit sizes can be
determined. The factors that generally inuence this decision
are: intended building usage, building layout, architectural
and aesthetic values, economics, geographical location, and
type of maintenance service available. The general results
may be a mixture of unit types within a given system. Daikin
Applied manufactures fan coil units to meet many needs
including ThinLine, HiLine
™
and Large Capacity models. For
Daikin McQuay product information, please go to
www.
DaikinMcQuay.com.
Basic design data
Prior to selecting individual unit sizes, a design engineer must
x or determine the following factors:
• Inside and outside wet and dry bulb design temperatures
• Total and sensible heat gains and losses of the area to be
served
• Ventilation air
• Properties of the heating and cooling medium
• Available electric power service
• Any special design requirements of the building or
system
Unit Size
The capacity ratings presented in this catalog are provided
for initial unit selection only. Water cooling and heating
capacities, unit air
ow, static pressure and glycol solutions
are all incorporated into the program to provide the
best possible selection. Consult your Daikin Applied
representative for a selection tailored to specific applications.
Unit sizes for the ideal system should be selected by
calculating peak load requirements due to unusually high
occupancy or severe climatic conditions and with fans
operating at high speed. Ordinary day-to-day cooling and
heating requirements are then achieved at low and medium
speeds.
The initial unit selection should be checked for air volume in
the design system and the cooling capacities checked against
actual operating conditions. While units selected on the basis
of sensible load will generally meet the total cooling load,
total load should be checked in all cases.
The unit size is generally selected on the basis of matching
the sensible cooling capacity of the unit with the calculated
requirements when operating at high speed.
Coil Types
Standard coils are designed to meet both cooling and heating
requirements in a typical system. Two additional levels of
enhanced primary coils are available to meet the total and
sensible requirements of any application.
Heating requirements for two-pipe systems are generally
met by employing the same water ow rate as cooling and
adjusting the entering hot water temperature to obtain a
matching unit heat output at low fan speed.
Four-pipe systems are generally designed by specifying
the ow rate through the separate heating coil to meet the
required heat load with the fan operating at the desired fan
speed. Daikin Applied offers two coil options for preheat and
o
ne option for reheat.