Method for Installation of HVAC System (Part-3)

(C) Y Joints

  • Confirm the Y branching piping matches allowable designs from the Installation Manual

  •  Installed with single end of Y Joints always towards outdoor unit.
  • The branch joint of outdoor side must be installed horizontally.
  • The branch joint of indoor side can be installed horizontally or vertically.
  • Y Joints are supported before and after.
  • “Y” joints are the correct size and match the locations as shown on the Selection Report.
  • Maintain a minimum distance of 20″ between branching joints, headers, elbows and equipment.
  • Recommend horizontal runs to be 3 times that of the vertical when traps cannot be avoided

  • Between two branch joints ≥1m
  • Between branch joints and indoor unit ≥0.5m
  • From the inlet or outlet of branch joint, there should be straight pipe with length at least 0.5m

(D) Copper Pipe Length:

The permitted length and drop difference

Pipe length Max. pipe length <= 240 Meter
Equivalent length from the first branch to the farthest indoor unit <= 40 Meter
Drop height Drop height between indoor unit and outdoor unit <= 110 Meter
Drop height between indoor units <= 30 Meter

  • Record the actual liquid pipe length for future reference when charging additional refrigerant.

Split AC Copper Pipe Length

A.C Capacity Maximum Pipe Length Maximum Indoor & Outdoor Height Difference
0.5 Ton 15 Meter 5 Meter
0.6 Ton 15 Meter 5 Meter
0.75 Ton 15 Meter 5 Meter
1 Ton 20 Meter 10 Meter
1.5 Ton 25 Meter 10 Meter
2 Ton 25 Meter 10 Meter
2.5 Ton 30 Meter 10 Meter
3 Ton 30 Meter 20 Meter
3.5 Ton 30 Meter 20 Meter
4 Ton 30 Meter 20 Meter

(E) Drain Pipe

  • Water leakage test
  • Check leakage of water pipe After finished installation of drainage pipe, filled the pipe with water,
  • Waiting for 24 hours to check whether there’s any leakage.
  • Check leakage from the indoor unit
  • Charge water from the check hole of indoor unit to check whether the water can be exhausted smoothly or not

Size of Drain Pipe

Condensate water volume : V (L/h)=Indoor Unit (HP)x2  I.D (mm)  Thickness (mm)
V ≤ 14 Φ 25 3
14 V ≤ 88 Φ 30 3.5
88 V ≤ 175 Φ 40 4
175 V ≤ 334 Φ 50 4.5
334 V Φ 80 6
*If Slop is <1% than select next higher Size of Drain Pipe

(F) Insulation of Refrigerant Pipe & Drain Pipe

  • The slip-on method of installation is used for insulation on new refrigeration piping
  • The inside of the insulation is coated with a powdered lubricant, making it easy to slip the insulation over the pipe.
  • Small amounts of powdered lubricant may enter the open ends of pipe or tubing. This dust must be kept out of refrigeration systems. Plug the open ends of pipe before slipping on the insulation.
  • Apply insulation only when the pipes are clean, dry, and unheated or uncooled. The surface to be insulated must be free of rust.
  • Never stretch insulation when sealing the joints. It is better to compress it slightly. Use pieces of insulation that are at least as long as the section of pipe to be insulated.
  • Always use the insulation that is properly sized for the pipe it is to cover. Do not stretch it over the pipe.
  • Do not crowd insulation-covered pipes. Space pipes far enough apart to allow for the free circulation of air. Air movement is an extra safeguard against surface condensation of cold pipes, especially under hot, humid conditions.

  • All piping insulation must be properly sealed to minimize heat loss and control condensation. On cold lines, open pipe insulation joints may allow the formation of condensation, increasing the potential for or contributing to possible pipe or tubing corrosion. Seal insulation joints
  • Do not compress piping insulation at joists, studs, columns, ducts, hangers, etc. This is important because the insulation will lose thermal efficiency where it is compressed. On cold systems, surface condensation may occur where insulation is compressed
  • Apply a coating of an approved contact-type adhesive to both butt ends to be joined.

  • Before butting the ends together, allow the adhesive to set until it is dry to the touch but still tacky under slight pressure. Join the surfaces.
  • Cut open the inside wall of the elbow, taking care not to damage the opposite wall. The slit-open elbow should slip over the fitting. Apply adhesive to the seam (not to the butt ends), allow to tack dry, and fit over the fitting. Press the seams together working from the ends toward the center of the elbow.

  • Finally, wet seal the butt ends to the incoming lengths of insulation. Cut the incoming lengths so that the butt joints are in slight compression.

  • Do not wrap the gas and liquid refrigerant pipes together.
  • Avoid compressing the insulation as much as possible
  • Be sure there are no cracks or deformities in the insulation at bends in pipes.
  • If necessary double the insulation to prevent condensation from forming in warm or humid areas.
  • Cut off excess insulation.

 Referent Pipe Insulation

Pipe Pipe size Insulation Type (EPDM or NBR)


Standard conditions 86°F (30°C), < 85% High humidity conditions(a)
86°F (30°C), >85%
Liquid Pipe 1/4″ (6.35 mm)  To 3/8″ (9.52 mm) 3/8″ (9 mm) 3/8″ (9 mm)
1/2″ (12.70 mm)  To  2″ (50.80 mm) 1/2″ (13 mm) 1/2″ (13 mm)
Vapor Pipe 1/4″ (6.35 mm) To 7/8″ (22.23)  1/2″ (13 mm) 3/4″ (19 mm)
  • Wrap insulation around the entire surface of each pipe, including the refrigerant pipes from the indoor unit to the service valves inside the outdoor unit, the branch joints, distribution header, and connection points on each pipe.

  • Do not wrap the vapor and liquid refrigerant pipes together.
  • If vapor and liquid pipes are in contact with one another, use thicker insulation and make sure the pipes are not pressing tightly against one another.
  • Pipe connections between the indoor unit and EEV kit: Leave 3/8 in. (10 mm) of space between vapor and liquid pipes.
  • Be sure there are no cracks or deformities in the insulation at bends in pipes or where hangers are attached to pipes.
  • If necessary, double the insulation to prevent condensation from forming in warm or humid areas.

Insulation Thickness

Refrigerant Pipe Insulation Drain Pipe Insulation
22.22mm To 28.58mm 19mm 25mm / 32mm /40mm 6mm
12.7mm To 19.05mm 13mm / 19mm
6.35mm To 9.2mm 9mm / 13mm

Method for Installation of HVAC System (Part-2)

Indoor Unit Installation:

(a) High Wall Unit:

  • The installation of the split air conditioners is a crucial job. If the installation is done accurately  air conditioner will give optimum cooling, but if it is not done properly we won’t get the desired cooling effect. A poor installations also leads to frequent maintenance problems.
  • Several factors have to consider during the installation of split air conditioner.
  • Strength of wall to hold the AC
  • The indoor unit of split AC must be installed on a wall strong enough to hold the unit’s weight.
  • Proper spacing between wall and AC unit
  • The indoor unit of split AC requires at least 15 cm of open space surrounding its top and sides for proper air flow.
  • Appropriate installation height from ground
  • Mount the indoor unit of split AC at a height of 7 to 8 feet above the ground for adequate cooling inside the room
  • Correct tilt angle of indoor unit
  • While fixing the aluminum bracket on wall make sure that the bracket is given a slight tilt angle, so that the indoor unit of split AC, when fitted is also at a slight angle to enable unrestricted flow of the condensed water from the drain pipe.

(b) Cassate Type:

  • Air inlet and outlet should be clear of obstructions, ensuring proper airflow throughout the room.
  • Condensate can be easily and safely drained.
  • A structure strong enough to withstand four 4 times the full weight and vibration of the unit.
  • Filter can be easily accessed for cleaning.
  • Leave enough free space to allow access for routine maintenance.
  • Do not install in a laundry room or by a swimming pool due to chemical sorrowing cassette coil.

  • Indoor Unit Hanger Mounting Depending on the type of ceiling, attach the threaded hanger bolts securely to the support stud. Before lifting the indoor unit to the installation location, insert the upper nuts, flat washers (with insulation), flat washers (without insulation), lower nuts and double locking nuts on the threaded hanger bolts.
  • Lift the Ceiling Cassette main body to the threaded hanger bolts. Insert the unit mounting brackets between washers and then fasten it securely.
  • Pack the indoor unit with plastic bag after hoisting to protect them from dust entering.


  • Allow for ventilation intake and exhaust air based on maximum outdoor unit fan capacity.
  • Select the size, type and orientation of architectural louvers with adequate “net free area” face velocity to ensure the total external static pressure from the outdoor unit fan does not exceed design limitations.
  • No obstructions must be placed in front of the louver that could hamper the free flow (throw) of air.
  • Roof top openings and / or discharge and supply louvers must be equipped with screens to prevent bird and insect infiltration.
  • Louver Angle is not more than 15 Deg Horizontally
  • Space between Louvers is not more than 4 inch
  • If louver open rate is too small it will create noise from louver blade vibrations. Insufficient air flow exchange creates drop in outdoor unit performance and may create air conditioner stop operating.

Refrigerant & Drain Pipe Installation Work:

(a) Pipe Support:

  • A properly installed pipe system will have sufficient supports to avoid pipes from sagging during the life of the system.
  • Sag­ging pipes become oil traps that lead to equipment malfunction.
  • Pipe supports must never touch the pipe wall; supports shall be installed outside (around) the primary pipe insulation jacket. Insulate the pipe first because pipe supports shall be in­stalled outside (around) the primary pipe insulation jacket.
  • Field provided pipe supports must be designed to meet local codes. If allowed by code, use fiber straps or split-ring hangers suspended from the ceiling on all-thread rods (fiber straps or split ring hangers can be used as long as they do not compress the pipe insulation). Place a second layer of insulation over the pipe insulation jacket to prevent chafing and compression of the primary insulation in the confines of the support clamp.
  • As necessary, place supports closer for segments where potential sagging could occur. Maximum spacing of pipe supports shall meet local codes. If local codes do not specify pipe support spacing, pipe shall be supported:
  • Wherever the pipe changes direction, place a hanger within twelve 12 inches on one side and within twelve 12 to 19 inches of the bend on the other side. Support piping at indoor units, Y-branch, and Header fittings
  • Supports must be strong enough. The supports should be full thread booms, and their diameters should be ≥ 10mm.
  • Dual nuts should be adopted to fix the indoor unit under the ceiling.
The distance between the supports of the copper pipes.
Diameter Distance (m)
 ≤ 20 mm 1 Meter
20 To 40 mm 1.5 Meter
 ≥ 40 mm 2 Meter

(b) Cutting & Welding of Refrigerant Pipe:

  • Install piping to be as short and direct as possible, with a minimum number of joints, elbows and fittings. Piping must be installed parallel to the building lines..
  • Pipes must be cut accurately to measurements established on site and must be worked into place without springing or forcing.
  • Pipes must be installed as permit free expansion and contraction without damage to joins or hangers.
  • All piping shall be installed in accordance with the mechanical design. Any deviation shall be submitted for prior approval to the mechanical engineer prior to installation.
  • Refrigerant piping diameter, thickness, and temper is selected according to length, as specified in this section.
  • Cut or extend field-supplied piping as needed. To extend pipes, braze or using flared pipe connections Refer to “Pipe Cutting,” “Nitrogen Flushing While Brazing,” and “Flared Pipe Connections,”
  • Make sure that pipes are free of dirt, debris, and moisture, and do not leak.
  • Braze or use flared pipe connections to install piping. Refer to “Connecting Piping to the Single- Phase Outdoor Unit,”
  • Pipe Cutting
  • Using a pipe cutter, cut the pipe so that the cut edge is at 90° to the side of the pipe.
  • Use a reamer to remove all burrs at the cut edge. Examples of correctly and incorrectly cut pipes.

  • Selected copper tube must be of suitable wall thickness for higher operation pressures.
  • Use a tubing cutter, do not use a saw to cut pipe. De-bur and clean all cuts before assembly
  • Brazing:
  • While brazing refrigerant pipes, flush them with nitrogen gas. Use a pressure regulator to maintain a flow rate of 1.76 ft3/h (0.05 m3/h) or more.
  • Dry Nitrogen: Dry nitrogen must be used during all brazing (pressure regulated to 3 PSI) to prevent copper plate or oxidation formation.
  • Always use a non-oxidizing material for brazing. Do not use flux, soft solder, or anti-oxidant agents. If the proper material is not used, oxidized film may accumulate and clog or damage the compressors. Flux can harm the copper piping or refrigerant oil.
  • Requirement of welding:
  • When welding the copper pipe, nitrogen is necessary to protect the copper pipe.The pressure of the nitrogen is 0.02 MPa
  • Charge the nitrogen to the copper pipe at the beginning of welding and only.when the copper is fully cooled down, the nitrogen can be removed
  • If Nitrogen is not used, Welding will create Oxide on copper pipe inside and outside, which cannot be removed and it jams the refrigerant flow and damage the Compressor.

  • Warning:
  • Do not braze in an enclosed location. Do not allow the refrigerant to leak during brazing. Always test for gas leaks before and after brazing.
  • Do not allow the refrigerant to leak during brazing; if the refrigerant combusts, it generates a toxic gas. There is risk of fire, explosion, and physical injury or death.
  • Flaring: Flared tube ends should have a smooth, even round flare of sufficient length to fully engage the mating surface of the flare nut, without protruding into the threads.
  • Use a flaring tool specifically designed for flare joints in R-410A systems, which creates deeper flares than those by made by traditional flaring tools. This flaring tool has an eccentric mandrel and clutch type handle. Follow the flare tool manufacturer’s directions for using the tool.
  • Slide the flare nut over the pipe to be flared. Slide the end of the pipe into the hole on the flaring bar that fits the pipe, leaving a length of pipe, determined by tool type (see table), extending above the flaring bar. Clamp it down.
  • Remove the pipe. The end of the pipe that you flared should look like the end of a trumpet. See examples of correctly and incorrectly flared pipes.

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