Mixing Box (Optional) - Daikin PreciseLine Series Installation And Maintenance Manual

Thermal Expansion Valve (TEV)
For each unit size there are two TEV options available
(Table 46). TEV Option 1 is optimized for the standard
entering air and suction temperatures while option 2 is
intended for applications with higher entering air tem-
peratures and lower suction temperatures.
Thermal Expansion Valve Installation
The TEV should be located directly below and as close
to the distributor as possible. The distance between
them should not exceed 18" and should minimize the
use of any bends or elbows between. The sensing bulb
from the TEV should be attached to a horizontal section
of the suction line within 12" of the coil header using the
proper mounting straps to ensure good thermal contact.
On suction lines 7/8" OD and larger, the bulb should be
installed in the 4 or 8 o'clock position. For smaller lines,
the bulb may be attached anywhere but the bottom. For
optimal performance, a TEV with an external equaliza-
tion tube is recommended. The equalization tube must
be soldered to the suction header by drilling a hole in the
header, inserting the tube and securing in place with sol-
der. Care must be taken to ensure that the equalization
tube is inserted to the proper depth and is free of crimps,
solder, debris, etc.

Mixing Box (Optional)

The optional mixing box includes a fresh air and return air
damper that are linked together and driven from the same
actuator. It may be ordered with or without the factory mounted
damper actuator. Those with the factory mounted actuator ship
pre wired to the main unit control box and do not require field
adjustment of the hardware or linkage.
For the mixing box ordered without the factory mounted
damper actuator one must be provided in the field that meets
the following criteria.
• Maximum range of rotation = 95°
• Maximum torque = 62 in/lbs
• On-off control = spring return
• Modulating control = 0-10VDC fail in place
• Damper shaft size = 0.5" diameter
A mounting plate is provided on the shaft side of the damper
frame to accommodate a variety of actuators. However, due
to the number of options, size variations, and arrangements
available, some actuators may require alternate field provided
mounting hardware. Proper support for the actuator is
important to avoid putting excess stress in the cabinet, linkage,
or damper
shafts. The installing contractor is responsible for mounting,
and wiring of the actuator and adjustment of the damper
linkage.
IM 1267-7 • PRECISELINE AIR HANDLER
Optional Mixing Box Damper or
Discharge Plenum Loss
For reference, losses are similar to those used in custom
openings, however, their coefficients are multipliers of velocity
pressure based on opening size. These are multipliers of
coil velocity pressure. The intake loss assumes a fully open
damper in line with the unit, based on the sudden expansion
into the unit of 2x the face area and 20% drag from the blade.
The discharge loss assumes the sudden expansion off the fan
of 10X then a sudden contraction at the discharge of 3x the
face area. Losses from a grille are not taken into account.
Intake, intake with damper or discharge plenum loss
= (( V*C ) / 4005)²
V = velocity through the opening
C: Straight intake without damper = 0.75
Turned intake without damper = 1.0
Straight intake with damper = 1.0
Turned intake with damper = 1.33
Straight discharge = 1.5
Turned discharge = 2
Example:
For a selection at 1000 ft/min, mix box with rear intake and
discharge plenum down discharge:
Intake loss is (1000*1/4005)^2 = 0.062"
Discharge loss is (1000*1.5/4005)^2 = 0.140"
Figure 88: Discharge and Mixing Box Examples
74
Physical Data
www.DaikinApplied.com