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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 

Summary of Contents for DM AHU

Page 1: ...LATION 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...

Page 2: ...rtificate 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 Uni...

Page 3: ...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...

Page 4: ...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...

Page 5: ...on 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...

Page 6: ...hipped 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 han...

Page 7: ...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 dama...

Page 8: ...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 equa...

Page 9: ...r 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 conden...

Page 10: ...he diameter of smaller pulley Table 2 Adjusted Pitch Diameter Model VPT100Z1 VPT120A1 A2 VPT139A1 A2 VPT156A1 A2 VPT177A1 A2 VPT178B2 Max Pitch mm 96 114 4 133 4 150 4 171 4 171 Min Pitch mm 82 9 96 1...

Page 11: ...ee 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 fla...

Page 12: ...out 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 Duc...

Page 13: ...ther 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...

Page 14: ...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 th...

Page 15: ...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 SE...

Page 16: ...ling 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...

Page 17: ...IR 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 de...

Page 18: ...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 isolato...

Page 19: ...he 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 exchan...

Page 20: ...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 A...

Page 21: ...Are the AHU sections joined with section joint properly Answer Yes No 4 Are the joining between AHU sections sealed properly Answer Yes No Start Up Checking 1 Is fan rotated in correct direction Answe...

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