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.

About Jignesh.Parmar (B.E,Mtech,MIE,FIE,CEng)
Jignesh Parmar has completed M.Tech (Power System Control), B.E(Electrical). He is member of Institution of Engineers (MIE) and CEng,India. Membership No:M-1473586.He has more than 16 years experience in Transmission -Distribution-Electrical Energy theft detection-Electrical Maintenance-Electrical Projects (Planning-Designing-Technical Review-coordination -Execution). He is Presently associate with one of the leading business group as a Deputy Manager at Ahmedabad,India. He has published numbers of Technical Articles in “Electrical Mirror”, “Electrical India”, “Lighting India”,”Smart Energy”, “Industrial Electrix”(Australian Power Publications) Magazines. He is Freelancer Programmer of Advance Excel and design useful Excel base Electrical Programs as per IS, NEC, IEC,IEEE codes. He is Technical Blogger and Familiar with English, Hindi, Gujarati, French languages. He wants to Share his experience & Knowledge and help technical enthusiasts to find suitable solutions and updating themselves on various Engineering Topics.

3 Responses to Method for Installation of HVAC System (Part-2)

  1. ahmad fairus says:

    Hi sir I have problem to start motor (5.5kW and 10Amp) using DOL starter system. the pump give to 40 – 50 amp during starting then the O/L relay goes trip. so the motor can’t start. Any advice from you to help me to solve the problem.

  2. Abdelhadi Amin says:

    Many thanks for valuable informations.

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