Daikin DM AHU User manual

MANUAL
INSTALLATION
OPERATION
MAINTENANCE
VER: O-AHU01-DEC20-15
The design and construction are subject to change without any notice for future improvement.
MODELS DM AHU
DS AHU
AHUR VRV AHU
Double Skin Modular Air Handling Unit

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Table of Contents
1. General ........................................................................................................................ 1
2. Shipment...................................................................................................................... 1
3. Handling / Rigging ........................................................................................................ 2
4. Storage ........................................................................................................................ 2
5. Assembly and Installation .............................................................................................. 2
6. Commissioning and Operation...................................................................................... 12
7. Maintenance ............................................................................................................... 14
8. Trouble Shooting......................................................................................................... 16
9. Appendix .................................................................................................................... 18
1. General
1.1 Foreword
This installation, operation and
maintenance manual is given as a guide to
user of air handling units. The manual
does not limit the users to add other
necessary procedures or services for the
continuous successful operation of this
equipment.
1.2 Warning Notes
Warning and Important notes are
appearing at appropriate places in this
instruction manual. Follow the warning
notes carefully to ensure correct operation
of the equipment and personal safety. The
manufacturer assumes no liability for
installation, operation and maintenance
undertaken by unqualified personnel.
1.3 Occupational, Health and Safety
Practices
Connection and start-up of the unit should
be done in conditions, which are in
conformity with Local Codes and
Regulations, especially in the field of
operation of electrical devices.
The mains voltage must not be turned on
before the unit is connected to the
protective system. It is forbidden to make
any repair and maintenance activities if
the power supply of the unit is not turned
off. Servicing person, who makes repair or
maintenance of the unit must have proper
qualifications resulting from the
qualification certificate, which is
determined by International, National or
Local Codes and Regulation.
Place of service should be equipped with
the necessary protective equipment, which
provide safe maintenance.
1.4 Unit Decommissioning and
Disposal
At the end of the unit’s useful life, a
suitably qualified engineer should
decommission it. The parts/materials must
be disposed of in a correct manner and
comply with the local laws and regulations.
The unit components shall be disposed of
or recycled as appropriate in the correct
manner.
2. Shipment
The items should be carefully checked
against the bills of lading to ensure all
crates have been received. All units should
be carefully inspected for damage when
received. Visible or concealed damage
should be reported immediately to the
carrier and filed damage claims.
WARNING
DAMAGE OR LOSS OF PARTS IN
SHIPMENT OR AT THE JOB SITE IS
NOT THE RESPONSIBILITY OF
MANUFACTURER.
Air handling units are constructed with
heavy-gauge steel or extruded aluminum
and are thoroughly inspected before
leaving the factory. Care must be taken
during installation to prevent damage to
units. Special care should be taken when
handling the blower section. All fans are
dynamically balanced before leaving the
factory. Rough handling can cause
misalignment or sprung shaft. Therefore,
blower fan and shaft should be carefully
checked before commissioning to avoid
more damage cause by unbalance fan.
Screws, bolts, nuts, etc. for assembly of
sections are supplied in a bag attached to
each section. All necessary gaskets are
fixed in the factory.

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3. Handling / Rigging
Air handling units can be delivered as
separate section or completely assembled.
To prevent damage to unit cabinet, a
specific lifting method for offloading the
units is recommended as shown in Figure
1. The spreader bars must be in position
to prevent straps or cables from rubbing
the frame panel. Ensure stability and
balance when lifting the units and avoid
twisting or uneven lifting. Uneven lifting
may lead to accident or fatality which is
out of factory responsibility. Care should
be taken to prevent coil connections, drain
pan connection, damper operators and
accessory section from damage.
Do not push hard on the unit it self of on
the metal base. Use large wooden beam
to evenly distribute the force. Dropping
the units will result in permanently
damage of ball bearing, fan shaft or
loosen coil from the mounting.
AHU with metal base
AHU with wooden base
Figure 1 - Lifting method when offloading units
Transportation on the building site should
be done using forklift truck or a crane
(See Figure 2). The forks must only be
applied under the unit base frame and not
against the panel. In case when fork of
the forklift is too short then suitable
extensions should be used.
Figure 2 - Transportation by forklift truck
4. Storage
For external storage prior to installation,
the units must be protected from dust,
rain, constant sun exposure and rodents.
Although covered in shrink-wrapped
plastic sheeting, this is not intended for
long-term storage and should be remove
as soon as it is offloaded. Unit therefore
should be more protected by tarpaulins or
similar. Avoid exposed the units for coil
connection damages by transient load.
The fan impeller or motor drive must be
rotated once every month. Should the
units be stored for a period of exceeding 6
months, then it is recommended that the
drive belts be removed and store
separately.
IMPORTANT
INSTALLATION AND
MAINTENANCE ARE TO BE
PERFORMED ONLY BY QUALIFIED
AND EXPERIENCED PERSONNEL
WHO ARE FAMILIAR WITH
NATIONAL AND LOCAL CODES
AND REGULATION.
5. Assembly and Installation
5.1 General
The system design and installation should
follow accepted industrial practice, such as
described in the ASHRAE Handbook.
These units are not designed to be
weatherproof (unless equipped with
canopy) and therefore should not be
installed outdoors. Flexible connections
should be used on the outlet and inlet
duct connections for all units. A minimal
amount of air leakage is normal on the
cabinet and it will not affect unit
performance. The air handling units are
not design to be suspended from the top
of the unit. Therefore, when the unit is
ceiling hung, make sure unit is supported
with a base rail of channel.

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5.2 Foundation
Adequate space should be left around the
unit for coils & drainage piping, filter
replacement, and maintenance. (See
Figure 3). If site access space for coil is
not follow recommendation, AHU need to
dismantle for coil replacement. The unit is
installed at a height that allows the
installation of condensate drain trap.
Figure 3 –Recommended minimum service
clearances
To minimize noise transmission, insulation
material (rubber pad) may be placed
between the unit base and the foundation
(See Figure 4)
Figure 4 –Air handling unit Plinth Foundation
5.3 Section Joint
Units that shipped in sections must be
carefully assembled to desired unit
arrangement. The air handling units are
design to use section joint brackets to
combine two sections. Section joints for
cabinet and base frame are shown in
Figure 5 and Figure 6. (provided when
cabinets are joined by intermediate-post
to intermediate-post arrangement)
Figure 5 –Cabinet Section Joint
Figure 6 –Base Frame Section Joint
The section joints are pre-installed on
cabinets and base frames as shown in
Figure 7 (For AHU combination of 2
sections and above). The joint for side will
located outside of AHU, joint for top
bottom will be located inside of AHU.
Figure 7 –Pre-installed section joints
To join two sections, install and level the
first section in position, then push the
second section close to the first section
after the alignment is correct as shown in
Figure 8.

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Intermediate to intermediate post joining
Figure 8 –Combine cabinets
Base frame section joints need to join with
bolts and nuts as shown in Figure 9.
Figure 9 –Tighten the base frame section joint
After base frame being joined, further
tighten the external cabinet section joint.
After the external section joints being
connected, then only followed by internal
section joints. Make sure all joint brackets
provided are tighten with bolt and nut as
shown in Figure 10. All the bolts and nuts
for the joining are provided and packed
with the unit.
Figure 10 –Tighten the cabinet section joint
WARNING
CABINET SECTION JOINTS ARE
NOT INTENDED FOR LIFTING
PURPOSE AND PULLING CABINET
FROM A DISTANCE TO JOIN
SECTION TOGETHER.
When the cabinets are penta-post to
penta-post arrangement or joining two
sections with different cabinet width, then
below type of section joints will be
provided. (See Figure 11)
Pentapost to pentapost joining
Figure 11 –Section Joint for pentapost to pentapost
or different width cabinets
Lastly, silicone sealant need to apply to in-
between section to seal the gap.
5.4 Vibration Isolator
Air handling unit fans are supplied with
internal vibration isolators.
5.4.1 Spring Vibration Isolator
For model with spring isolators, temporary
transport brackets are fitted to prevent
damage during shipment. All transport
brackets must be removed after

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installation and before commissioning.
(See Figure 12)
After removing the transport bracket,
adjust the spring’s height accordingly to
ensure the frame is level before
commissioning. Before turning the
adjustment nut, the locking bolt must be
loosened. Turn the adjustment nut bolt
clockwise or anti-clockwise to decrease or
increase the spring’s height. Tighten the
locking bolt after completing the
adjustment. (See Figure 13)
Figure 12 –Removing of transport bracket
Figure 13 –Spring Isolator Adjustment
5.4.2 Restrained Vibration Isolator
The following is applied for plenum or
other fan which is using restrained spring
isolator. (See Figure 14). 20mm U-shaped
plates are inserted between top plate and
base plate when shipped out from factory.
(See Figure 15).
Figure 14 –Restrained Spring Isolator
Figure 15 –Removing of U-Shaped Plate
5.5 Arrangement (VRV AHU)
Control box and expansion valve kit are
installed on the air handling unit. Figure
16 and Figure 17 show the proposed
arrangement of component. Item 2, 3, 5,
8 and 10 in Figure 16 and Item 2, 3, 6, 9
in Figure 17 will be supply by factory.
Refer to Installation and Operation manual
of “EKEQMCBAV3 / EKEQFCBA – Option kit
for combination of Daikin condensing units
with air handling units” for further
instructions.
Standard Air Series VRV AHU
Figure 16 - Standard Air Series VRV AHU Unit
1. Outdoor unit
2. Control box
3. Air Handling unit
4. Field piping (field supply)
5. Expansion valve kit
6. Outdoor unit power supply
7. Control box wiring
8. Air handling unit thermistors
9. Power supply and control wiring
for air handling unit and controller
10. Air thermistor control for AHU
11. Remote controller

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Outdoor Air Series VRV AHU
Figure 17- Outdoor Air Series VRV AHU Unit
1. Outdoor unit
2. Control box
3. Air Handling unit
4. Microtech III
5. Field piping (field supply)
6. Expansion valve kit
7. Outdoor unit power supply
8. Control box wiring
9. Air handling unit thermistors
10. Control wiring for control box and
Microtech III
11. Power supply and control wiring
for air handling unit and controller
12. Remote controller
5.6 Coil Installation/ Pipe Connection
5.6.1 General
The coil will perform as per rating only if
the airflow is uniformly pass-through the
coil surface.
IMPORTANT
HIGH VELOCITY SPOTS ON THE
COIL MAY CAUSE MOISTURE
CARRY OVER. THEREFORE,
UNIFORM AIRFLOW ACROSS COIL
SURFACE IS CRUCIAL.
External pipe-work must be adequately
supported to ensure load-free towards coil
connections. Swing joints or flexible
fittings are to be provided in all piping
connections, particularly those adjacent to
heating source, to absorb expansion and
contraction strains. Failure to comply will
result in damage to the coils & headers.
IMPORTANT
TO AVOID DAMAGING THE COIL
CONNECTIONS AT COIL HEADER,
IT IS ESSENTIAL TO HOLD THE
CONNECTOR / PIPE WITH TOOLS
WHILST APPLYING COUNTER
FORCE TO TIGHTEN THE JOINT.
(See Figure 18)
Figure 18 –Coil header connection method
Figure 19–Bulb orientation and position
Figure 19 shows the correct mounting
method and the position of TXV sensing
bulb according to the piping size.
IMPORTANT
WRAP WET CLOTH AROUND PIPE
BEFORE PERFORM BRAZING TO
PREVENT OVERHEAT PIPE AND
DAMAGE COMPONENT AT PIPING.
( Figure 20 )
Figure 20 –wrap wet cloth before brazing
AFTER PIPE-WORK DONE, SITE
INSTALLER MUST WRAP THE PIPE
CONNECTION WITH INSULATION
AND SEAL THE HOLES BETWEEN
PIPE CONNECTIONS AND PANEL.
5.6.2 Water Coil
Water supply, water return, drains and
vents connections are extending through

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the end panel of the coil section. All
connections are labeled on the end panel.
For control equipment, follow
recommendations from the manufacturer
regarding the types, sizing and installation
of equipment. Hot water coils are not
recommended to be used with entering air
below 40oF (4.4oC). Refer appendix 9.2 for
water quality.
5.6.3 Winterizing Water Coils
Coil freeze-up may occur due to air
stratification, failure of outdoor air
dampers and/or preheat controls. Routine
draining of water coils for winter shutdown
cannot guarantee zero freeze-up incidents,
which may result in coil damage. It is
recommended to completely drain the coil
and treated with anti-freeze solution.
Fill each coil independently with an anti-
freeze solution by using a small circulating
pump follow by complete draining. Check
the freezing point of anti-freeze before
proceed in each coil. Diluted effect
normally occurred due to a small amount
of water always remaining in each coil.
Therefore, ensure sufficient amount of
anti-freeze solution be remained in coil to
prevent freeze-up.
5.6.4 Direct Expansion Coils
For each coil, individual expansion devices
must be provided for header suction
connection. If the air flow through two or
more coils in parallel or stacked coil bank,
the suction piping must be installed in
such a way that refrigerant from one coil
suction header cannot reach another coil
suction header. The bulb for the control
valve must be attached to the header or
the coil or section of coil fed by valve and
not to a common header. When two or
more coils are connected to a common
suction line, never place the bulb on the
common line.
Thermostatic expansion valve is to be
equipped with external equalizer tubes
that are field connected to the suction line.
The valve should be in accordance to the
manufacturer recommendations, allowing
approximately 35-psi pressure drop
through the coil and distributor at full load.
Do not oversize the valve, proper
expansion valve operation is necessary in
order to realize the rated coil capacity.
IMPORTANT
CAREFULLY READ THROUGH
MANUFACTURING INSTRUCTION
FOR APPLING ANTI-FREEZE
SOLUTION. SOME PRODUCTS
WILL HAVE DIFFERENT FREEZING
POINT IN ITS NATURAL STATE
WHEN MIXED WITH WATER. COIL
FREEZE-UP IS NOT THE
RESPONSIBILITY OF
MANUFACTURER
It is not recommended to operate DX coil
for air-conditioning purpose at below
freezing suction temperature, 0oC which
will result frost build-up at fins surface. If
the full load operating point for the coil is
selected at a “safe” temperature, a system
analysis is required to check for the lowest
probable suction temperature at light load
condition.
5.6.5 Piping Diagram (VRV AHU)
For piping diagram of VRV AHU model,
please refer to the VRV ED or refer to
manufacturer for advices.
5.6.6 Drain Pan Trap
Drain pipes and traps must be at least
same diameter as the drain pan
connection. Drain pan must be level to
permit condensation from coil drain freely
for the recommended depth and distance
of drain trap installation. (See Figure 21)
Drain pan are not designed to be walked
on.
Figure 21 –Drain Trap Arrangement
5.7 Electrical Installation
Electric connecting should be compliant
with relevant local laws and regulations.

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All installation and management activities
must be carried out by qualified personnel.
Refer to the specific wiring diagram and
electrical component manual are attached
with the product before electrical
installation. Site contractor shall do
termination at site for wiring connection
between components that located at
different AHU sections and delivered
separately.
IMPORTANT
MAKE SURE ALL THE ELECTRIC
POWER DISCONNECT AND
SECURE FROM SWITCH ON
BEFORE DOING WIRING
CONNECTION
5.7.1 Motor Connection
The electric supply to the motor must
correspond to the rated voltage stated in
motor nameplate and be in conformance
with the National and Local Electric Code
and Regulations. Motor supplied able to
operate within 10% tolerance from the
nameplate voltage. Motor connection
details are contained in the cover of the
motor terminal box. (See Figure 22). The
fan section metal frame must be grounded.
Suitable electrical protection isolator
should be installed to protect the motor
and other electrical equipment.
Flexible conduit must be used when wiring
up fan motors to allow the fan motor to
move freely on its anti-vibration mounts.
Cables passing through panels must be
made with gland or grommet.
For inverter control, refer to the VFD
manual for wire size and requirements.
Figure 22 –3 phases motor connection diagram
5.7.2 Motor Cabling
Motor wiring must go downward from
motor terminal box to prevent
condensation water flowing into motor
and lead to a failure. (See Figure 23)
Figure 23 –Motor Cabling
5.8 Drive Belt & Sheave
Improper sheave alignment and belt
tension can cause excessive vibration,
premature failure of belts and bearings.
See Figure 24 for correct motor sheave
and fan sheave alignment.
Tensioning of the drive belt is achieved by
moving the motor in relation to the fan
(See Figure 25). When inserting new belts,
do not force belts over grooves, Loosen
the adjusting screw at motor base until
belt can slide smoothly over the grooves.
When all belts are in position, proceed to
adjust belt tension using the adjusting
screw and nuts on the motor base.
Use recognized belt tension gauge to
check the belt tension by apply a force
large enough at the center of the belt to
deflect the belt by 16mm per meter (See
Figure 26). The deflection force for any
belt should be within the minimum and
maximum force shown in table 1. Readjust
the tension to maximum value when it
drops to min. value. The deflection force
of factory setting is based on “Initial
Fitting”, re-tensioning as “Retension” after
the unit has run for 24 hours.
WARNING
OVER TENSION TOWARD DRIVE
BELT WILL CAUSE PREMATURE
FAILURE OF BELT AND BEARING
DAMAGE.

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Figure 24 –Alignment of belt pulley
Figure 25 –Belt tensioning
Figure 26 –Belt deflection distance
Table 1 - Belt Tensioning Force
Belt Section
Pulley
Diameter
Deflection Force (N)
Initial Fitting
Retension
Min
Max
Min
Max
SPZ
<70
12
17
12
16
71-90
15
22
15
19
91-125
19
27
19
24
SPA
<100
20
29
20
25
101-140
27
39
27
34
141-200
32
47
32
40
SPB
<160
36
54
36
46
161-224
46
67
46
58
225-355
53
79
53
69
Refer to factory specifications for tension values that are not included
Refer to the diameter of smaller pulley
Table 2 - Adjusted Pitch Diameter
Model
VPT100Z1
VPT120A1
/ A2
VPT139A1 /
A2
VPT156A1 /
A2
VPT177A1
/ A2
VPT178B2
Max. Pitch Ø (mm)
96
114.4
133.4
150.4
171.4
171
Min. Pitch Ø (mm)
82.9
96
115
132
152.5
146.5
Adjusting Factor(mm)
1.089
1.227
1.089
1.089
1.452
1.635
No. of Turning
Adjusted
Ø (mm)
Adjusted
Ø (mm)
Adjusted Ø
(mm)
Adjusted Ø
(mm)
Adjusted
Ø (mm)
Adjusted
Ø (mm)
0.25
94.91
113.17
132.31
149.31
169.95
169.37
0.5
93.82
111.95
131.22
148.22
168.50
167.73
0.75
92.73
110.72
130.13
147.13
167.04
166.10
1
91.64
109.49
129.04
146.04
165.59
164.46
1.25
90.56
108.27
127.96
144.96
164.14
162.83
1.5
89.47
107.04
126.87
143.87
162.69
161.19
1.75
88.38
105.81
125.78
142.78
161.24
159.56

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2
87.29
104.58
124.69
141.69
159.78
157.92
2.25
86.20
103.36
123.60
140.60
158.33
156.29
2.5
85.11
102.13
122.51
139.51
156.88
154.65
2.75
84.02
100.90
121.42
138.42
155.43
153.02
3
82.93
99.68
120.33
137.33
153.98
151.38
3.25
-
98.45
119.24
136.24
152.52
149.75
3.5
-
97.22
118.15
135.15
-
148.11
3.75
-
-
117.07
134.07
-
-
4
-
-
115.98
132.98
-
-
5.9 Accessory Items
5.9.1 Filter
Air handling units can be supplied with flat
filters and/or bag filters. There are 2 types
of filter frame, sliding frame or universal
clip. Insert the filter into the frame by
following airflow arrow indicated.
5.9.2 Mixing Box
Fresh air and return air dampers can be
linked together and drives by the same
actuator if both are same size. Care must
be taken to ensure dampers are in open
position while the fan is running whether
they are integral with central plant control
or associated ductwork under negative
pressure condition.
5.9.3 Variable Pitch Pulley
Modifications of the pulley diameter must
be done when stationery by moving the
adjustable flange. Each complete rotation
of one of the two disks results in a
variation of the pulley diameter. (See
Table 2 & Figure 27) When the required
diameter is obtained, adjustable flange is
locked by tighten the four clamp screws.
To get the same diameter in the two
grooves of pulleys, screw the two mobile
flanges on the central flange. Then
unscrew the two mobile flanges by the
same number of turnings to get the
required diameter.
Note that the belt centre line shifts when
diameter changes. Driven pulley may need
realignment.
Figure 27 –Variable Pitch Pulley
5.9.4 Heat Wheel
Follow Heat Wheel manufacturer
recommendations for proper installation
procedure. Apply silicone to air leak spots
at baffle plates. (If applicable)
Refer to assembly of heat wheel baffle
plates at Appendix 9.1 when the heat
wheel section not able to ship in complete
build up.
5.9.5 Heat Pipe
After installation of Heat Pipe with refers
to manufacturer recommendations, site
installer to install heat pipe baffle plates at
site, this is to avoid air bypass heat
pipe/main cooling coil from top and side.
(If applicable)
5.9.6 Electric Heater
Power supply to electric heater and
electric connection is in accordance with
wiring diagram in terminal box of electric
heater.
The rated voltage of electric heater is
240V, single phase.
IMPORTANT
IT IS ADVICED TO INTERLOCK
ELECTRICAL HEATER WITH
BLOWER TO ENSURE HEATER IS
NOT ENERGIZED WHEN THERE IS
NO AIR FLOW.

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5.10. Ductwork
Connections to unit cabinet are made by
site drilling into the frame on the unit inlet
or fan discharge collar. This should be
load-free toward cabinet collar when initial
positioned.
Compliance with the Codes of Practice in
duct assembly and acoustic layout are
necessary to ensure the best possible
performance of the unit whilst avoiding
excessive pressure loss in the duct system
and minimize undue air stream noise. Duct
connections to and from units should allow
straight, smooth airflow. Sharp turns in
the fan discharge should be avoided,
particularly turns opposed to wheel
rotation. Turning vanes should be used.
Discharge plenums or any abrupt change
in duct should be avoided.
Figure 28 –Discharge duct layout
Notes:
1. Elbows should not be closer than
2-1/2 times the Duct Equivalent
Diameter. (Refer to Formula 1)
2. Dampers should be placed at least
fan diameters downstream of the
fan discharge.
Formula 1 - Duct Equivalent Diameter
All duct joints, edges, opening area of top
roof (example: top discharge, top damper
and top roof with opening), must have
skirting and fully sealed to avoid leakage
and rain water seepage into the unit (if
unit is placed outdoor).
Figure 29 –Site to seal gap between roof and duct
Figure 30 –All edge to be seal by site if the flange
was sent separately / unit is CKD
For outdoor unit, the return duct should
be large enough to cover the exposed
area of AHU to prevent rain water from
seeping into the unit.
Figure 31 –Front view of Return duct to be large
enough to cover exposed area
Figure 32 –Side view of Return duct to be large
enough to cover exposed area
IMPORTANT
Top roof are not intended for
people to step on.

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5.11 Assembly of Complete Knock
Down Unit (CKD)
Due to container size constrain, some air
handling units are packed in unassembled
condition - CKD method. All parts required
are packed in section by section. It is
recommended to open one section at a
time to avoid confusion when assembly.
For CKD, additional drawing will be
provided for assembly at site.
5.12 Component Removal and
Replacement
5.12.1 Panel Removal
To remove side or top panel, simply
unscrew the fasteners located along the
aluminum clip on the frame of Air
Handling unit cabinet. Once the aluminum
clips are removed, lift the panel off.
5.12.2 Fan / Motor
The fan shaft, motor and drive
components can be removed and replace
through the access door opening or side
panel removal if additional access required.
For fan replacement, the entire fan
assembly can be pulled out from side or
front (for top discharge) of the cabinet.
Dismantle the intermediate fan supports
and canvas follow by loosening bolts &
nuts at motor and drive belts. Then
remove the belts and nuts from Fan
mounting frame. Take out the fan and
replace with new fan with care. Re-
connect the shaft and bearings and fan
assembly.
5.12.3 Coil
The coil can be pulled out from side or top
of cabinet. The coil is fastened with bolts
and nuts on the coil support bracket at the
end plate and baffle plate. Before removal
of coil, ensure the piping connections at
header are disconnected. In case where
two coils are stacking, remove the drip
pan and join brackets which holding the
two coils together.
For DX coils, it is advisable that the
refrigerant is to be pumped into the
condenser. If this is not possible,
refrigerant shall be purged out.
WARNING
DO NOT HEAT ANY PART ON DX
COIL IF REFRIGERANT STILL IN
THE SYSTEM. HEATING UP WILL
CAUSE DANGER OF HIGH
PRESSURE INSIDE THE COILS.
6. Commissioning and Operation
6.1 Pre-run Check
6.1.1 Preparation
The complete air handling unit and all
accessory components should be
thoroughly cleaned and all dust & debris
completely removed.
Make sure that all transport brackets and
packing have been removed.
Ensure all screws, bolts and nuts on AHU
are secured tightly (not loose during AHU
transportation or handling).
Ensure all panel and belt drive settings are
secured due to change during shipment or
installation.
In case additional equipment is installed at
site, ensure air leaking spots are being
seal with additional baffle plates or seal
with silicone to prevent air bypassing.
WARNING
ISOLATE THE ELECTRICAL &
MECHANICAL ENERGY SOURCE
AND PADLOCK THE SWITCH
BEFORE SERVICING THE FANS
AND MOTORS.
6.1.2 Fan / Motor
Make sure the fan impeller can rotate
freely by hand. Check the tension and
alignment of the belt drive.
Check motor connections and make sure
correct voltage is supplied. If standby
motor is available, make sure only one
motor to power source.
Seal end of fan motor conduit (if
applicable) and the motor terminal box
with silicon sealant.
VFD/Frequency Inverter for TEFC motor
can only vary the frequency within 30 to
60 Hz in order to control the motor
rotation speed. For VFD setup, make sure
the VFD settings according to
recommendations at VFD manual.
When multiple fan with multiple VFDs,
fans must set up to always start
simultaneously and with same speed.

- 13 -
6.1.3 Fan Array
Fan array is available for EC plug fan.
Ensure all fans are control to run
simultaneously and with same speed.
Fans running at unequal speeds can result
uneven airflow that cause performance,
sound, vibration problems that lead to
failure.
In case one of the fan is down, blank off
plate shall be temporarily installed on the
nonfunctional fan to prevent air re-
circulation while waiting fan replacement
(See Figure 33). If present of differential
pressure controller, ensure the pressure
tube of nonfunctional fan is capped and
amend the setting of controller accordingly.
Figure 33 - Fan Array with Blank-off Plate
6.1.4 Vibration Isolator Mount
Ensure the vibration isolator mounts and
flexible connections allow the fan and
motor to move freely without constrain.
For the fan with Restrained Spring Isolator,
ensure that the Alu Angle plates are
removed from the restrained spring
isolator before commissioning.
IMPORTANT
The clearance between flanges
of “Top plate” and “Base plate”
for restrained spring isolator
should be approximately 10-
20mm.
6.1.5 Coils
Check the pipe-work to coil is correctly
connected and the fins are free from
foreign matter or damage.
Check that the condensate drain is trap.
Ensure good sealing of silicon around the
coil headers and drain pipe.
6.1.6 Damper & Filters
Check all dampers are operating correctly
as per design.
Make sure all filter media are installed in
correct airflow direction.
6.1.7 Panel & Section
Ensure all access panels are in position
and secure. Make sure all necessary
section joints are in place.
6.1.8 Electric Heater
Electric Heater – Before starting-up,
ensure that the air flow through the
heater should not be lower than 2.0 m/s
to avoid overheating heater.
WARNING
FOR 380-415V/3PH, STAR
CONNECTION WITHOUT NEUTRAL
(Figure 34), UNBALANCED PHASE
VOLTAGE MAY CAUSE DAMAGE
ON THE ELECTRIC HEATER.
Figure 34 - Wiring Diagram without Neutral
FOR 380-415V/3PH, STAR
CONNECTION WITH NEUTRAL
(Figure 35), NEUTRAL POINT MUST
BE CONNECTED IN ACCORDANCE
WITH WIRING DIARGRAM IN
ORDER TO CARRY CURRENT DUE
TO UNBALANCED PHASE
VOLTAGE.
IMPORTANT
SAFETY THERMOSTAT IS FOR
OVERHEATING PROTECTION
ONLY, NOT FOR CONTROL
PURPOSE. DEFAULT SETPOINT IS
60˚C.
IT MUST BE CONNECTED TO
CONTACTOR (WHETHER
SUPPLIED BY FACTORY OR SITE)
TO CUT-OFF HEATER IN CASE OF
OVERHEATING HEATER.

- 14 -
Figure 35 - Wiring Diagram with Neutral
Heat Wheel –Ensure the heat wheel can
rotate freely by hand.
Heat Pipe –Ensure installations are as per
manufacturer recommendation.
6.2 Start-up Check
Competent, well-trained personnel must
be employed in the following operations to
ensure Safety Rules and Regulation being
adhered to at all time.
IMPORTANT
FAILURE TO PROVIDE MOTOR
OVERLOAD PROTECTION COULD
RESULT IN MOTOR DAMAGE.
CONNECT THE MOTOR TO AN
OVERLOAD PROTECTIVE DEVICE
THAT IS RATED IN COMPLIANCE
WITH THE APPLICABLE CODE.
a. Check the rotation of the fan impeller.
If the fan rotates in opposite direction
from desire, reverse any two phase
connection at motor terminal.
b. Check that there is no unusual noise
or vibration. Stop and investigate if
found. (refer to section 8)
c. Measure the voltage and drawn
current of the motor. The drawn
current must not exceed the full load
current mentioned at motor
nameplate.
6.3 After first 48 hours of operation
a. Make sure complete isolate the
Electrical source.
b. Re-check and Re-tension the drive
belts due to stretch.
c. Check and adjust the pulley alignment
to ensure the motor fixing is properly
secure.
d. Check all bearing, wheel bolts & nuts
and sheave set screws (or cap screw)
are in secure position.
CAUTION
HIGH AIR TEMPERATURE IN FAN
SECTION CAN CAUSE MOTOR
OVERHEAT AND DAMAGE. ON
DRAW-THROUGH AIR HANDLERS,
ADJUST THE DISCHARGE AIR
TEMPERATURE OF THE HEATING
SECTION NOT TO EXCEED 1040F
(400C).
6.4 Fan Operating Limits
The fan operating limits for forward curve
and airfoil fan are shown on the Table 3.
Total static pressure should be limited to
1000 Pa for forward curve and 1500 Pa for
backward curve/airfoil fan.
Table 3 - Fan Operating limits
Blower
Size
Forward Curved
Backward
Curve/Airfoil
Max.
RPM
Max.
kW
Max.
RPM
Max.
kW
200
3800
3
5700
2
225
3400
4
5400
3
250
2600
4
4400
3
280
2400
6
3900
4
315
2100
6
3500
5
355
1900
8
3100
6
400
1700
8
2700
8
450
1400
10
2500
11
500
1200
11
2200
11
560
1100
15
1900
15
630
900
15
1700
15
710
850
25
1500
30
800
750
25
1350
30
900
650
30
1150
35
1000
600
30
1050
35
6.5 Installation of VRV AHU Control
Box (EKEQ)
For installation VRV AHU Control Box,
please refer to the Installation And
Operation Manual in VRV ED or refer to
manufacturer for advices.
6.6 MicroTech III Commissioning
MicroTech III is an option. For
commissioning of MicroTech III, please
refer to the MicroTech III Commissioning
Manual in VRV ED or refer to
manufacturer for advices.
7. Maintenance
7.1 Fan / Motor
Check for soiling, corrosion, damage and
tendency of excessive vibration.
Check that all bolts and nuts and flexible
connections are securely fixed.

- 15 -
Check that vibration isolator mounts are
functioning well.
Inspect for any obstructions or blockages
at air intakes and discharges.
Check fan bearings are secured and no
undue noise by observe/listen using metal
bar as a conductor.
If unit equipped with belt guard, check
that it is fitted correctly and secure.
If there is any undue noise or knocking
from bearing, replace both bearings. Fan
bearing are grease for life, but larger units
with standard bearing require semi-annual
or annual lubrication at bearing greasing
nipple. Recommended lubricants are
Standard Din 51823, K3N or ISO XM2.
7.2 Drive Belt
Belts that are split or have frayed edges or
any other sign of damage (rubber shred
on floor) must be replaced in full set.
IMPORTANT
DURING MAINTENANCE AND
SERVICING, UNIT MUST BE
COMPLETELY ISOLATED AND
PRECAUTIONS TAKEN TO
PREVENT ACCIDENT FROM
HAPPENING.
Check the belt tension and alignment, re-
tension and re-align if necessary. Refer to
Section 5.7 for belt tensioning procedure.
New belt drive must be re-tensioned after
the first 48 hours of operation.
For replacement of belts, remove the belt
guard before starting work. To change the
belts, first loosen the adjusting screw and
move the motor towards the fan to enable
old belts to be taken off and put on of
new belts. (Matched belts must be used)
Tension the belts by following instruction
at Section 5.7.
7.3 Coil Section
Periodic cleaning of coils is required. Dirty
coils have tendency to increase airside
pressure drops and reduce cooling/heating
efficiency. Dry cleaning is done by using a
powerful vacuum cleaner on the dust-
accumulated side. If coil is very dirty, coils
need to be removed for wet cleaning by
trained personnel. Ensure coil fins are not
damage when performing dry/wet
cleaning. In the event that fin edges have
been bent, treat with aid of a coil comb.
Check that frost protection is working
before starting of each winter season.
Ensure the frost sensor is correctly
installed and working within desired
temperature range.
For direct expansion coils, do not use hot
water or steam to clean these coils. During
normal operation, the fin block must not
be ice up. If this occurs, check the
refrigeration system.
Check that drain pan and drain trap are
free from blockage and water
accumulation at pan.
7.4 Filter Section
During system start up, filters are likely to
become rapidly blocked.
Disposable filters and bag filters must be
replaced each time when pressure drop
reaches the indicated dirty condition by
D.M. Manometer. Washable filters must be
cleaned periodically.
7.5 Dampers
Check for dirt accumulation, damage and
sign of corrosion. Clean with cloth or high
pressure air. Check damper blade turning
manually or central control for smooth
operation.
Table 4 - Recommended Maintenance intervals (based on 12 hours operating time per day)
Component
Description
Action
Maintenance interval
Weekly
Monthly
3 Monthly
6 Monthly
Yearly
Fan / Motor
Fan in general
Check / Clean
●
Fan bearing
Check / Replace / Greasing
●
Motor in general
Check / Clean
●
Motor bearing
Check
●
Motor temperature
Check / Repair / Replace fan
●
Belt drive tension
Check / Re-tension
●
V-Belt condition
Check / Replace
●
Corrosion
Check / Treat / Repair
●
Bolt & nut secure
Check / Tighten
●

- 16 -
Excessive vibration
Check / Resolve
●
Flexible connection
Check / Tighten
●
Vibration isolator
Check / Tighten
●
Intake air not obstruct
Check / Clear
●
Coil Section
Fin block
Check / Clean
●
Frost protection
Check / Apply
●
Drain trap clog
Check / Clear
●
Corrosion
Check / Treat / Repair
●
Leakage
Check / Repair
●
Bolts & nuts secure
Check / Tighten
●
Filter
Resistance (Washable)
Check / Clean
●
Resistance (Disposable)
Check / Replace
●
Damper
Dirt accumulation
Check / Clean
●
Sign of damage
Check / Repair / Replace
●
Turning torque
Check / Repair
●
Electrical
Control
Control box & wiring
Check / Repair / Replace
●
Protection breaker
Check / Calibrate
●
Internal lighting
Check / Replace
●
Electric Heater
Dirt accumulation
Check / Clean
●
Safety cut out
Check
●
Functionality
Refer Manufacturer
Recommendation
●
Heat Wheel /
Heat Pipe
Functionality
Refer Manufacturer
Recommendation
●
Moisture
Eliminator
Dirt accumulation
Check / Clean
●
7.6 Electric Heater
Check for dirt accumulation and clean if
necessary with a soft brush. Check the
safety control, cables and connections
operation.
IMPORTANT
AIR VELOCITY SHOULD NOT BE
LOWER THAN 2.0 m/s.
7.7 Heat Wheel & Heat Pipe
The unit should be maintained in line with
the manufacturer recommendation. Please
refer installation and maintenance manual
for details.
7.8 Moisture Eliminator
Check the dirt accumulation at the blades,
remove and clean the blades if necessary.
Ensure the blades are correctly positioned
and not distorted.
7.9 Maintenance Plan for Air
Handling Units
The schedule provided in Table 4 gives
recommended maintenance intervals for
the AHU unit (Guideline only).
Intervals are based upon normal running
conditions, in a moderate climate and
assuming 12-hour running. Units operating
outside these guidelines may require
shorter or longer maintenance intervals.
8. Trouble Shooting
Use Table 5 to assist in trouble-shoot the
malfunction in Air Handling Unit operation.
Table 5 - Trouble shooting analysis
Symptom
Probable Cause
Recommended Action
Motor fail to start
a) Blown fuse or open circuit breaker.
b) Improper wiring.
c) Mechanical Failure.
a) Replace fuse or reset circuit breaker.
b) Check wiring with diagram supplied.
c) Check motor & drive rotate freely &
bearing lubricant.
Motor stall
a) Short circuit or phase to earth.
a) Check line phases and terminal block

- 17 -
b) Overload motor.
c) Low line voltage.
d) Over tensioned belts.
e) Misalign drive.
connection.
b) Reduce system load.
c) Check supplied voltage within motor
voltage range.
d) Adjust belt tension.
e) Re-align drive.
Motor overheats
a) Overloaded motor.
b) Motor Fan dirty/ damage.
a) Reduce load or replace larger motor.
b) Clean/ replace motor fan.
Low air volume after
start up
a) Fan rotating in wrong direction.
b) Air damper not properly set.
c) Pressure drop by filter above
recommended level.
a) Reverse any two phase connection at
motor terminal.
b) Ensure system correctly balance & set.
c) Change filters –(complete bank).
Excessive motor noise
a) Motor mounting bolt loosen.
b) Worn motor bearing.
a) Tighten motor mounting bolt.
b) Replace bearing and seals.
Excessive noise from
unit
a) Worn fan or motor bearing.
b) Fan impeller rubbing on inlet cone or
cover.
c) Incorrect drive belts tension.
a) Replace bearing and seals.
b) Check clearance or remove for repair.
c) Check tension.
Excessive vibration
a) Fan impeller out of balance.
b) Transport bracket not remove.
c) Improper pulley alignment.
d) Over-tensioned belts.
e) Vibration isolator damaged.
f) Motor shaft bend.
g) Bad bearings.
h) Loosen bearing hold down bolt
i) Fan & motor section not evenly
supported on foundation.
j) Fan assembly’s tolerance is out of
range.
a) Consult manufacturer.
b) Remove transport bracket.
c) Check pulley alignment.
d) Re-tension belts.
e) Replace vibration isolator.
f) Send the motor for repair.
g) Replace bearing and seals.
h) Tighten hold down bolt.
i) Re-adjust and tighten.
j) Conducts dynamic balancing.
Bearing excessively hot
a) Over-tensioned belts.
b) No lubricant.
c) Over-lubricant.
d) Misaligned bearing.
a) Re-tension belts.
b) Apply lubricant
c) Purge and clean surface.
d) Check & re-align shaft.
Water present in cooling
coil drain pan or overflow
a) Drain trap clog.
b) Incorrect hydraulic trapping.
a) Clean & clear clog.
b) Resize trap and check air break
arrangement.
Premature drive belts
failure
a) Improper tension or alignment.
b) Incorrect belt being fitted.
c) Dirt or grease on belts.
d) Belt rubbing.
e) Worn sheaves.
a) Check tension and alignment.
b) Replace with full set.
c) Clean belt & pulley, check for grease
leak.
d) Remove obstruction.
e) Replace sheaves.
Belt swelling or softening
a) Excessive contamination by oil, certain
cutting fluids or rubber solvent.
a) Replace with full set. Isolate the source
of contaminate.
Belt whipping during
running
a) Incorrect tensioning.
a) Re-tension belts.
Filter collapsing
a) Filter block with dirt.
b) Air velocity too high.
a) Replace at advised dirty condition.
b) Check unit running conditions.
Note: The table is intended as a diagnostic aid.

- 18 -
9. Appendix
9.1 Assembly of heat wheel
1. Heat wheel unit bottom section has already assembled with heat wheel support assembly
and heat wheel baffle bottom when delivered.
2. Placed the baffle centre to the penta-post / centre-post or panel.
3. Placed the heat wheel on the heat wheel support assembly in the bottom section from
opening on top/side, depends on the design.
4. Screw the heat wheel to the heat wheel support assy. by using self-drilling screws.
5. screwed the heat wheel baffle left/right and centre
6. Assemble the top cabinet section to the bottom section. If required, remove some panel to
facilitate assembly work of heat wheel. Screw the baffle left/right and centre to top section
cabinet.
7. Assemble the heat wheel baffle top.
8. Assembled back the remaining panels.
9.2 AHU Water Quality
Water quality requirements: Water softening treatment must be given in advance to prevent
scaling in the heat exchanger which may affect heat exchange effect. Moreover, water
without softening treatment may form scale in the pipe to increase water resistance which
will affect water flow and pump work efficiency.
Table 6 –Water Quality Requirements
Item
Baseline
Value
Tendency
Corrosion
Scaling
Benchmark
items
pH (25°C)
-
7.5 ~ 9.0
O
O
Conductivity (25°C)
µS / cm
<800
O
O
Chloride Ion Cl-
mg (Cl-)/ L
<200
O
Sulfate Ion SO42-
mg(SO42-) / L
<200
O
Acid Consumption (pH=4.8)
mg(CaCO3) / L
<100
O
Total Harness
mg(CaCO3) / L
<200
O
Reference
items
Ferrum Fe
mg(Fe) / L
<1.0
O
O
Sulphion S2-
mg(S2-) / L
0
O
Ammonium Ion NH4+
mg(NH4+) / L
<1.0
O
Silicon Oxide SiO2
mg(SiO2) / L
<50
O
Note : O - factor related to the tendency of corrosion or scaling
9.3 AHU Commissioning Check Sheet

- 19 -
AHU Commissioning Check Sheet
General Information
Project :
Unit Name :
Unit Model :
Unit Serial Number :
Installation Date :
Commissioning Date :
Initial Checking (Pre-start Up)
A) Fan Section
1. Are all fasteners tightened?
Answer: Yes No
2. Motor winding Resistances.
U1-U2: __________ V1-V2: __________ W1-W2: __________
3. Motor Megger Test.
U-Ground: __________ V-Ground: __________ W-Ground: _________
4. Are all electrical connections tight and of correct wiring?
Answer: Yes No
5. Correct incoming voltage that supplied to motor
L1-L2: __________ L2-L3: __________ L3-L1: __________
6. Rotate fan wheel whether it can rotate freely and without abnormal noise.
Answer: Yes No
7. Are pulleys aligned?
Answer: Yes No
8. Is belt tensioning correct?
Answer: Yes No Value:_______________
9. Are lock blower bases (blower base shipment bracket) removed?
Answer: Yes No
10.Are spring isolators adjusted to be same height?
Answer: Yes No
11.Ensure no construction debris or foreign material left inside AHU.
Answer: Yes No
12.Correct duct turning elbow direction and sufficient effective duct length.
Answer: Yes No
*Please attach duct layout from reference.