Method for Installation of HVAC System (Part-1)


Purpose:

  • This method explains the Procedures or sequence of activity for safely and efficiently installation and Testing of Refrigerant Pipes , Drain Pipes ,Indoor and Out Door Unit of HVAC System as per standard Practice and Code.

General Equipment & Tools:

  • The equipment that will be engaged for Installation of Cable works will be
  • Lifting crane , Transportation vehicle, Fork Lift
  • Winches, Pulling Rope , Welding machine
  • Lubricant (Soap based, wax based), Cleaning agent (CRP)
  • Copper pipe Flaring tools
  • Vacuum Pump,
  • Brazing Torch , Brazing Rod , Oxy-Acetylene Brazing Kit ,Wire Brush
  • Nitrogen Cylinders , Soldering Tools
  • Crimping tool, Drilling Machine with various Bits , Grinding Machine , Cutting Machine
  • Electrical Tool Box, Cable Cutter, Screwdriver, Pliers, Spanner.
  • Ladder , Scaffolding / Mobile scaffold
  • Nylon rope, Marker , Leveling device , Tape measure
  • Removable Barricades , Portable Lights
  • Testing Equipment for System
  • Multi meter ,Clamp Meter
  • Refrigerant / Nitrogen cylinder,
  • Vacuum Gauge

Storage & Material Handling:

  • The storage area must be free from dust and Water leakages / seepages.
  • Manufacturer recommendation shall always be followed in loading/unloading and storing of Material.
  • Material and its accessories shall be unloaded handle with care in designated area of the Store (Do not directly drop to Ground) to avoid any damages.
  • Materials shall be stored in a dry place which is free from water or from weather effects and protection should be given to the material by means of covering the material with Tarpaulin sheet.
  • The Material will be stacked / unload in the site store on a proper stand on wooden loft on a flat surface at a sufficient height from Ground.
  • The A/C Units should be kept on the wooden platform and covering with polythene to protected from any dust or mechanical damages
  • For storing the copper pipes:
  • If pipes will be used soon, nozzle should be sealed by plastic bag or tape.
  • If pipes will be stored for a long time, the pipes should be charged into 0.2 to 0.5MPa Nitrogen and the nozzle should be sealed by welding.

Inspection of Materials:

  • Check The Material according to its Type, Size, Make
  • Physical Damages Inspection:
  • Damage on Pipes and Units.
  • Damage on insulation of Cable
  • In case of any damages observed during inspection, the Material shall be returned to the supplier for replacement.

 Installation of Outdoor Units :

 (a) Transporting / Lifting the Outdoor Unit

  • Use appropriate moving equipment to transport outdoor Unit, ensure the equipment is capable of supporting the weights. When lifting the unit, use lifting straps and place around the unit.
  • Always lift the unit using appropriate size of lifting straps rated to carry the unit weight and long enough to maintain a maximum of a 40° angle as shown.
  • When moving / adjusting the placement of the outdoor unit, always hold the unit by the corners. Moving the outdoor unit using the side intake holes on the frame may damage the frame.
  • Consider the unit’s center of gravity before lifting. Hoist the unit with the center of gravity centered among the lifting straps. There is a risk of the product falling and causing physical injury.
  • Lift the outdoor unit from the base at specified locations. Support the outdoor unit at a minimum of six points to avoid slippage from the rigging apparatus.
  • Do not lay the unit on its side and do not slant the unit more than 30 degrees.

  • On a supporting structure that can bear the weight of the outdoor unit. The supporting structure can be a base on the ground, on a waterproof roof, or in a pit. With sufficient clearances around the unit for service and repairs. In a well-ventilated location. Away from strong wind.
  • Away from direct exposure to rain or snow. Where there is no risk of flammable vapor leakage. Where there is no exposure to salt, machine oil, sulfide gas, or corrosive environmental conditions.

(b) Selecting the Best Location for the Outdoor Unit(s)

  • Don’ts:
  • Do not install the unit in an area where combustible gas may generate, flow, stagnate, or leak. These conditions can cause a fire.
  • Do not install the unit in a location where acidic solution and spray (sulfur) are often used or in environments where oil, steam, or sulfuric gas are present.
  • A location that allows for optimum air flow and is easily accessible for inspection, maintenance, and Where piping between the outdoor unit and indoor unit(s) / heat recovery units are within allowable Limits.
  • Avoid placing the outdoor unit in a low-lying area where water could accumulate.
  • If the outdoor unit is installed in a highly humid environment (near an ocean, lake, etc.), ensure that the site is well-ventilated and has a lot of natural light (Example: Install on a rooftop).
  • Where operating sound from the unit will disturb inhabitants of surrounding buildings.
  • Where the unit will be exposed to direct, strong winds.
  • Where the discharge of one outdoor unit will blow into the inlet side of an adjacent unit (when installing multiple outdoor units).

  • If the outdoor unit is not placed on a roof, place it on the leeward side of the building or in a location where the unit will not be ex­posed to constant wind.
  • If placement exposes the unit to constant wind activity, construct a wind break in front of the unit. Follow the placement guidelines set

  • Avoid installing the outdoor unit where it would be directly exposed to ocean winds.
  • Install the outdoor unit on the side of the building opposite from direct ocean winds.
  • Select a location with good drainage and periodically clean dust or salt particles off of the heat exchanger with water.
  • Ocean winds may cause corrosion, particularly on the condenser and evaporator fins, which, in turn could cause product malfunction or inefficient performance.
  • If the outdoor unit must be placed in a location where it would be subjected to direct ocean winds, install a concrete windbreaker strong enough to block any winds. Windbreaker height and width must be more than 150% of the outdoor unit, and be installed at least 27.5 inches away from the outdoor unit to allow for airflow.

  • Rubber anti-vibration pads are necessary to avoid vibration.

  • Foundation can be made of channel steel or concrete.

  • Reserve the space for discharging condensate water from outdoor units.
  • The outdoor unit should be placed neatly, and reserve enough space for maintenance.
  • The outdoor unit should be installed in the place that is dry, well-ventilation and close to the indoor units.

Method for Installation of Cable & Wire (Part-2)


(A) Cable Laying in Excavated Ground:

(a) Formation of Cable Trench.

  • Check the area of excavation by referring As Built drawing to find out crossing of any underground Services i.e. Gas Line, Water Line or other Cable. Check the indication marks, signs, manholes nearby area and find out the path of old services.
  • If there are structures adjacent to the work area, proper temporary supports shall be provided to the adjacent structure prior to start excavation.
  • Excavation near the existing electrical cables, instrumentation and control cables, sewer line, gas lines and any other service line shall take all necessary precautions to protect the services with proper supports & covers.
  • Ensure the working area at any confined space is free from any Hazardous Gas by proper Gas testing using the Gas testing instrument.
  • Required sign boards such as “DEEP EXCAVATION” “MEN WORKING”, “DANGER” and warning boards will be placed to indicate the excavation work. The area of excavation will be cordoned by using safety barricading to stop trespassers.
  • In open areas the excavation shall be carried out by using the machineries.
  • If the excavation level is below the local water table level suitable dewatering system shall be designed and installed in such a way that alterations and extensions to the system during operations are possible.
  • The width of the excavated Cable trench shall be as per specification or as per approved Drawings.
  • The trench shall be excavated up to the required depth of 0.76 Meter from the existing ground level or as per Specification or as per approved Drawing.
  • The Cable trench shall be kept dry during cable installation operation. The contractor shall deal with the dispose of water so as to prevent any risk to the cables and other materials.
  • Debris, rocks and unusable materials shall be removed from Excavated Trench on daily basis and it will dump at the approved dumping Location of from the site.

(b) First Layer of Sand:

  • The bottom of the trench shall be backfilled with a layer of clean and fine sand bedding of 100mm thickness or as per the approved Drawing.
  • The fill material shall be tamped. Any hard material which could damage the cable will be removed
  • Inspection of sand bed will be carried out prior to commencement of cable pulling.

(c) Cable Laying:

  • Cables are laid over the clean and fine First Layer of sand bedding.
  • Rollers must be used where cables are installed in an open trench using a pulling rope and eye; cable rollers are to be used at frequent intervals to support the cables and must never be more than 3 meters apart.
  • Care must be taken to ensure that the cable does not enter or leave the rollers at an angle that exceeds the bending radius of the cable.
  • The Pulling rope must be attached to the cable by a stocking grip with pulling eye.
  • The cable shall be drawn into the trench manually, before the pull commences, to prevent the winch to move along with the cable.
  • The cable shall be drawn into the trench smoothly with a minimum of stops and at an average speed of between 9 to 12 meters per minute, to avoid irregular movement.
  • Cables shall be arranged properly to minimize crossovers, twists.
  • All Cable shall be laying parallel to each other and cable dressing should be done properly
  • Cable identification tags shall be installed on both end of cable after the cable pulling.

(d) Second Layer of Sand:

  • The cables shall be backfilled with approved clean and fine Sand / backfill Material of 100mm thickness or as per the approved Drawing.
  • The fill material shall be tamped. Any hard material which could damage the cable will be removed
  • Inspection of sand bed will be carried out prior to commencement of Cable Protection layer.

(e) Cable Protection:

  • Cable protection tiles / Bricks / Warning Taps are laid above the second layer of dune sand filling.

(f) Back Filling:

  • Backfilling materials shall be free from stones or rocks (larger than 50 mm), fossil content, vegetation and its roots, waste materials, Material containing gypsum or other soluble salts greater than the allowable limits which might prevent proper compaction or cause to inadequately of performance.
  • Backfilling area shall be backfilled with approved material compacted in layers by suitable equipment like plate compactors, vibratory roller compactors, etc., until the specified density has been obtained.
  • Sufficient Water is poured to match the required Moisture content.
  • Intermediate cable markers to be firmly attached to the cables.
  • The thickness of fill material shall not exceed 150 mm where manual compaction methods are adopted.

(B) Cable Laying in Cable Tray / Trunking:

  • Before laying of Cable , Cable Tray work should be completed form the one end to other end of the Cable route
  • The cable tray must be cleaned and free from any dust or water dampness, before pulling the cables.
  • Use cable rollers in cable trays to avoid damage on cables during the pulling process.
  • From cable reel to cable tray, the cable is fed from the top of the reel to maintain required curvature. Sheaves, or a shoe, may be used to guide the cable into the tray.

  • Cable rollers shall be placed at every 6-12 meters or less if required to avoid touching of the cable to tray.
  • Cable laying will generally start from one end of the route length from other suitable point if required.
  • The number and size of cables drawn in to a particular cable tray shall not be exceed that allowed in specifications.
  • At any time of Cable laying only one cable should be laid on cable tray, after laying first cable necessary dressing and cable tie should be fixed than after that second cable should be lay.
  • Cut the cables to required length at both ends, seal the ends with adhesive insulation tape roll and keep in the box or enclosures to ensure no damage can occur to cables.
  • Cables shall be arranged properly to minimize crossovers, twists
  • Control cables will be laid along the LV cables. HV cables to be laid in separate trays
  • All control cables will be installed at a minimum distance of 100mm from power cables unless otherwise agreed with consultant as per site conditions.
  • After completion of all cables in the same route the cables shall be dressed and clamped.
  • All cables in horizontal or vertical runs will be secured to the trays by nylon fasteners / ties.
  • Cable identification tags as per specifications shall be installed on both end (at sending and receiving ends) of cable after the cable pulling.

(C) Cable Laying in the Building

  •  In case of Cable lay inside the buildings, the drums will be placed outside the buildings and the cable pulled in the opposite direction. After reaching the other end the length of the cable required for reaching the location inside the building will be measured and then cut the cable.
  • The cable is fed from the cable reel directly into the conduit at floor level.
  • The cable is fed from the bottom of the reel so that its curvature is continuous with no reversed bends.

  • Do not pull cable directly across short, sharp angles. After pulling completely out of one side of the enclosure, feed cable into the other side of the enclosure and pull that segment
  • Unloading equipment should not come in contact with the cable or its protective covering.

(7) Wires Pulling in Conduit:

  • Proper marking / selection of location on site to be done prior to commencement of installation works.
  • Complete a mockup installation before main works and get its approval.
  • Make sure that all conduits and boxes in both ends are free from damages and blockages etc and installation is approved.
  • Blockage shall be checked by inserting the draw wire and checking that it reaches to the other end without any disturbance.
  • Use of Steel fish wire shall be made for drawing of wires. Wires shall be drawn with adequate care.
  • Once the conduit is not blocked the wires shall be pulled using the draw wires while ensuring no damage occurs while pulling.
  • Pulling compound or lubricant shall be used for pulling the wires where required.
  • Use soap based pulling compound for short runs i.e. less than 20 meters for semi conductive insulated wires.
  • Use wax based pulling compound for the runs greater than 20 meters for semi conductive insulated wires.
  • While pulling the wires care should be taken to not insert the pull tension greater than the manufacturer allowed limits.
  • Separate conduits shall be run for lighting and power circuits and also for telephone cables. To avoid any cross talk and extraneous interference in the telephone circuits, all telephone wiring conduits shall be run with a sufficient clearance from the power and lighting conduits.
  • All separate circuits from DB’s shall have separate neutral to the points. Common neutral between separate circuits are not permissible.
  • As far as possible wiring shall be run in conduits. All conduit wiring shall be complete with continuous earth as per I.E.R.
  • The wiring shall be carried out as specified.  ‘Power’ and ‘heating’ wiring shall be kept separate and distinct from ‘Lighting’ wiring. The wiring shall be done on the distribution system with main and branch distribution boards at convenient physical and electrical centers and consideration shall be given for neatness and good appearance.
  • The wiring shall be done in the ‘Looping System. ‘Phase’ or ‘live’ conductors shall be looped at the switch box and neutral conductor can be looped from the light fan or socket outlets.
  • 5 sq. mm PVC wires in green color are to be run continuously in conduits for continuous earthing. The earth wire should be connected to GI Switch boxes and DB boxes by tapped screws.
  • No bare or twist joints shall be made at intermediate points in the through run of cables.
  • Bare or twist joints shall be carried out with due care and preferably through proper junction boxes.
  • If any joint becomes unavoidable such joints shall be made through proper cutouts or through proper junction boxes open to easy inspections.
  • Electrical Load should be balance on all the three phases for an even distribution. Before commencement of work, the contractor shall seek the approval of the Consultants / Site Engineer on the distribution of balancing of loads and circuits. The wiring shall be done by the process of looping the live conductors and the neutral wires. 
  • Color coding of wires
  • Phase : Red, Blue, Yellow,
  • Neutral: Black,
  • Earth: Green.
  • Adequate extra length shall be left at termination points. 

(8) Excess or Spare Cable Storage:

  • Store Cable reels on hard surface so that the flanges will not sink and allow reel weight to rest on cable.

(9) Cables Identification / Marking of Cables:

  • Install the tags / labels as per project specifications and as per approved material submittals.
  • Cable marking shall be positioned properly to read and identify
  • For Buried / Surface mounted cables tagging / Labeling will be corrosion resistant tags (with engraved or stamped for the identification number of the cable, voltage Rating, conductor size and make) or as per project specifications and as per approved material submittals.
  • Cables shall be identified at feeders i.e. the sending and receiving ends (outgoing cables in SMDB’s and final DB’s) about 50mm below the gland.
  • All termination shall be provided with tight fitting covering sleeves.

(10) Duct Seals:

  • After installation of all Cables, all cable ducts / Hume Pipes / Sleeves entering substations and buildings to be duct sealedto prevent the ingress of water and gas.

(11) REFERENCES

  • IEC 60228, BS 6360.
  • BS 5467.

(12) Flow Chart:

  

%d bloggers like this: