1. PURPOSE: To establish a procedure for Method statement of Heating Ventilation & Air Conditioning (HVAC) system.
2. SCOPE:
This procedure is applicable to all Heating Ventilation & Air Conditioning (HVAC) system installed by Companies.
3. APPLICABLE CODES, AND STANDARDS:
This procedure shall conform to the following codes and standards (as applicable)
– ASHRAE
– AHRI
– ASSE
– ASME
– ASTM
– SMACNA
– MEMA
– AWS
– INTERNATIONAL MECHANICAL CODE
– MSS
In case of conflict between the applicable project specifications, codes & standards and this procedure client specifications shall govern unless agreed by ZCC in writing by the owner.
4. WITNESS OF INSTALLED ITEMS:
4.1. HVAC system installation shall be subject to test and inspection under witness by the and/ or OWNER’s representative at any reasonable time and place before, during and after installation as per approved ITP.
4.2. Installation of equipment, duel work and piping shall be in accordance with this procedure.
5. HVAC SYSTEM INSTALLATION WORK PROCEDURE :
5.1. Duct Hangers & Support Installation:
5.1.1. Supports for Rectangular ducts when suspended from above shall be installed on two opposite side of each duct.
5.1.2. Supports for Rectangular ducts shall be riveted, bolled, or metal screwed to each side of the duct at not more than the intervals specified.
5.1.3. The support system shall not cause corrosion by galvanic action at points of contact with the duct.
5.1.4. Concrete fasteners shall be installed after the concrete has been poured and the forms have been removed.
5.1.5. The support system shall not penetrate enclosures containing fluids or electrical wiring in such a manner to create a hazard.
5.1.6. Horizontal duct shall have a support within the feet of each elbow and within 4 feet of each branch intersection.
5.1.7. When ducts are supported from wall they shall be located against the wall or maximum of 2″ away from wall.
5.1.8. The supports system shall not penetrate a bearing member in such a manner as to cause excessive loading on the member.
5.1.9. Circular bands shall not be less than one inch wide nor lass than equivalent to the gauge of the duct material does it support.
5.1.10. Ducts shall be equipped with tight circular bands extending around the entire perimeter of the duct at each specified support interval.
5.1.11. Fastener (for supporting ducts from wall) shall be localed within 1″ of the duct edge (wall side) and within 2″ of the duct outer edge. Minimum of 3 on 24″ width and up is required in addition to ones
from edges.
5.1.12. Rectangular duct risers from floor shall be supported by angles or channels secured to the sides of duct with welds, bolts, sheet metal screws, or blind rivets. Fasteners shall be located within 2″ of the duct edges, locate others at evenly spaced interval.
5.1.13. Angles shall be at 12 feet intervals for rectangular and round duct risers.
5.1.14. All duct hanger & supports details shall be according to the drawing.
5.2. Duct Installation:
5.2.1. Duct Work shall be installed in accordance with approved General Construction Drawings, Specifications, and Manufacturer’s Installation Manual.
5.2.2. Rectangular elbows shall be provided with Turning Vanes.
Note: For low velocity systems only.
Exception: No turning vanes required if the throat radius is equal to the duct width.
5.2.3. Ducts shall be isolated from their Air Handling System (Fan, Fan Coil, AHU’s, etc) by Flexible Connections.
5.2.4. Flexible Duct Connector shall not exceed 8 feet in overall length and shall not have bends greater than 30 degrees.
5.2.5. Splitter dampers shall not be used for duct branch take-offs.
5.2.6. All building exhausts shall be directly to the outside with a point of discharge of at least 1.5 m away from any open able window or door, and a minimum of 1m above and 3 m horizontally away
from any air intake.
5.2.7. Metal ducting shall be grounded, provide jumpers al flexible duct.
5.2.8. Metal Ducts shall be installed at least 100 mm from Ground level.
5.2.9. Joints, seams and fittings of duct systems shall be made substantially airtight by means of tapes, mastic, gasketing or other approved methods.
5.2.10. If air leakages in ducts located outside of buildings are exposed to weather, they shall receive exterior duct sealant.
5.2.11. Exterior ducts sealant if exposed to direct sunlight shall be ultraviolet ray and ozone-resistant or shall be painted with a compatible coating that provides such resistant (SMACNA Para S1.9 g).
5.2.12. Seal class C shall be provided for 2″ w.g. pressure class duct Construction. Class C: Transverse joints only
5.2.13. Installation of duct Shall be done with proper alignment.
5.2.14. All duct work shall comply with SMACNA standards suitable for 2″ w.g. pressure class.
Material Specifications: Material Confirms to: ASTM A653
Material: Galvanized Iron sheets LF Quality
Zinc Coating: G-90
Thickness: As per General Construction Drawings.
5.3. Duct Installation:
5.3.1. Duct joints shall be sealed prior to insulation.
5.3.1.1. Duct Surface to be cleaned properly before applying adhesive.
5.3.2. Light test shall be performed in sections prior to insulation (if required by the client). There is no need to verify leakage control by field testing when adequate methods of assembly and sealing are used. Leakage tests are an added expense In system installation. It Is not recommended that duct systems constructed to 3 in. wg (750 Pa) class or lower be tested because this Is generally not cost effective(SMAGNA).
In case of requirement. the Light test shall be performed with heavy duty halogen lamps (500 or 1000 Watts lamps), which will located inside the dueling and the leakage in the duels shall be traced and sealed properly with the sealant.
5.3.3. Mechanical fasteners, adhesive, tapes, metal straps or any other means at the intervals specified in the construction drawings or specification shall be used in the installation of the duct insulation.
5.3.4. Duct insulation (For supply and return air duels only) shall be done on the installed duct by leaving 50mm on both sides of duct and shall be erected. After installation of ducts and proper alignment,
duct joints shall be sealed and insulated properly.
5.3.5. Insulation applied to the exterior surface of ducts located in buildings shall have a flame spread index of not more than 25 and a smoke density index not exceeding 50 when tested as a composite installation including insulation, facing material, tapes and adhesive as normally applied.
5.3.6. The density of Glass cloth (woven glass fiber fabric) shall be plain weave, pre-sized a minimum 270 g/m2. Coating shall be of Foster chemical as applicable and ensure proper finishing.
5.3.7. Ducts shall be insulated in accordance with 73-TMSS-01, TCS-K-100 & TES-K-100. All Supply and return air ducts, located outdoors or exposed to unconditioned air shall be insulated with 50mm thick.
All Supply and return air ducts, located outdoors or exposed to unconditioned air shall be Insulated with 25 mm thick.
Material Confirms to: ASTM C612, Type 18
Material: Fiberglass Board Insulation
Density: 56 kg /m3
Thermal Conductivity: 0.033 w/m C at 24°C mean temperature.
Flame. Spread/ Smoke developed rating: 25/50 or less.
Thickness: 25mm for inside building & 50 mm for Exposed / outside dueling.
5.4. FLEXIBLE DUCTS:
Flexible ducts shall be installed in accordance with SMACNA standard.
5.4.1. The bends of the flexible ducts shall not exceed the diameter of the flexibles, and shall not exceed 180 degree turns.
5.4.2. The length of the flexible ducts shall not exceed 1.5 meters. If the length of the flexible ducts exceeds 1.5 meters, round rigid ducts shall be installed before the flexible Ducts.
5.4.3. The flexible ducts shall be supported every 1.5 meters {max.) to avoid ii from sagging and touching the false ceiling.
5.5. Grills & Diffusers :
5.5.1. Grills and diffusers shall be installed to distribute the amount of air in every room. Refer to approved standard detail drawings.
5.5.2. Grils and registers shall be installed with self tapping screws to the wall or to the ducts as per shop drawings.
5.5.3. Supply grills or registers shall be installed with volume dampers easily adjustable from the front.
5.5.4. Return grills or registers shall be installed without volume dampers as per requirement.
5.5.5. Supply ceiling diffusers shall be installed with deflectors and volume dampers. The type of the diffusers shall be in accordance with the false ceiling.
5.5.6. Return ceiling diffusers shall be installed without volume dampers, and it shall be the same model with the supply diffusers.
5.6. Smoke & Fire Dampers :
5.6.1. The fire dampers shall be installed where ducts penetrate fire rated wall/ floors in accordance with manufacturer’s recommendation.
5.6.2. All fire dampers must be installed in between walls so that when fire or excessive hot air pass through it, the damper shall be closed by actuator.
5.6.3. In other cases that the fire damper cannot fit between wall openings, fire dampers can be installed before or after the wall provided that the fire damper must touch the wall to ensure heat
transmission.
5.6.4. An access door of 12″ x 12″ (min.) opening shall be provided on each fire dampers, to reach the blade in order to reset the fire damper after ii is activated. Refer to approved standard detail drawings.
5.6.5. The location of the fire dampers shall be as specified in the approved IFC drawings.
5.7. Volume Dampers & Back Draft dampers :
5.7.1. Volume Dampers:
5.7.1.1. All volume dampers shall be installed in accordance with SMACNA standard or equivalent.
5.7.1.2. Refrigerant Piping shall be carried out as per standard construction drawings and IFC drawings to suil site conditions.
5.7.1.3. All volume dampers operated manually shall have a handle which can be lock to a certain setting.
5.7.1.4. All volume dampers operated by motors shall have an extended shaft for the installation of the actuators/motors.
5.7.2. Back Draft Dampers:
5.7.2.1. All back draft dampers shall have a parallel blades linked to each other.
5.7.2.2. The installation of the back draft damper should be checked so that the blades are free from obstructions and that it open on the flow of air. Or closed by the pressure built on the opposite side.
5.7.2.3. Gravity back draft dampers are closed down ward, the length of the blades shall be free from any obstruction so that the blades will return when there is no air flow.
5.7.2.4. If the back draft damper is placed horizontally so that it will open down ward, the damper shall have a counter weight to enable the damper to close on no flow position.
5.7.2.5. The location of the back draft dampers shall be as specified in the approved shop drawings.
5.8. Refrigerant Pipe Installation and Insulation:
Refrigerant Piping shall be carried out as per standard construction drawings and IFC drawings to suit site conditions. Take extreme care to keep refrigerant tubing/piping clean and dry prior to installation. The following procedures should be followed:
5.8.1. Use only refrigeration grade copper tubing, properly sealed against contamination. Copper tubing often contains wax and other trouble-some contaminants. Short radius elbows can also be used and ensure to size.
5.8.2. Refrigerant piping should be designed and installed in accordance with approved IFC drawing.
5.8.3. The horizontal sections of the suction line should always slope towards the condensing unit. There should be 1/2 inch drop for each 10 feet of line, which is sufficient to return oil.
5.8.4. Suitable P-type oil traps should be located at the base of each suction riser to enhance oil return to the compressor.
5.8.6. The oil trap can be constructed at the base of suction risers which carry on upward gas flow.
5.8.6. No trap should be placed directly ahead of the compressor. This is to prevent slugging of the compressor with oil or liquid refrigerant trapped there.
5.8.7. Replaceable core type filter driers are recommended on higher capacity units. Do not leave the filler drier open to the atmosphere any longer, than absolutely necessary. Pressure Test to be done for ref piping (300 Psi) and kept the system for 12 hrs, to ensure they are free from any leakage.
5.8.8. After successful pressure testing, Suction lines must be insulated with closed cell (approved material), to prevent condensation. Liquid lines require no insulation unless they run through
high temperature areas.
5.8.9. Voids.
5.8.10. All piping should be kept short and with as few fittings as possible. This is to prevent excessive pressure drop In the lines. Do not clamp the lines together without insulation, unless it is necessary to use them to provide a heal exchanger.
5.8.11. Lines should never be left loose or unsupported. Isolation or vibration-free hangers are to be used. Do not attach lines directly to a building if you want to eliminate vibration and noise.
5.8.12. Refrigerant Piping shall be carried out as per standard construction drawings and IFC drawings to suit site conditions.
5.9 Brazing of Refrigerant Pipes:
5.9.1. When brazing refrigerant lines, an inert gas should be pass through the line at low pressure to prevent scaling and oxidation inside the tubing. Dry nitrogen is preferred. It is recommended that
a max. 35% silver brazing alloy be used on joints on copper to copper joints. Before joining 2 metals together, be sure the surface is free from grease, rust and oxides.
5.9.2. Limit the soldering paste or flux to the min. required to prevent internal contamination of the system. Flux only the male portion of the connection, never the female. After brazing, remove
surplus flux with a damp cloth. Brazing Procedure Specifications enclosed.
5.10. HVAC Equipment:
5.10.1. HVAC equipments shall be installed in accordance with this procedure and shall conform to Installation and Operation manuals as per recommendation.
5.10.2. HVAC equipments shall be installed with vibration pads or as required. If spring Isolators are to be used, the installation of spring isolators shall be in accordance with the weights recommended by Zamil. The number of vibration pads or spring isolators shall be as per Zamil’s recommendation. Refer to catalogue & detail drawings.
5.10.2.1. DX type Air Handling Units:
5.10.2.1.1. Ensure that the correct equipment is allocated to the specified zone. Confirm that the unit will fit within the space provided with adequate service access for the unit and all piping and electrical lines before installation.
5.10.2.1.2. Ensure the electrical supply conforms to the unit nameplate.
5.10.2.1.3. Prepare the mounting position (concrete pad, I-beam base, steel stand or ceiling hangers) in relation to anti-vibration pads, power supply, control wiring and pipework.
5.10.2.1.4. Depending upon the model, the unit should be mounted either level or with a slight slope towards the drain.
5.10.2.1.5. If the unit is suspended from the ceiling prepare the mounting system and secure it with threaded steel rods and expansion bolts or any suitable fixtures with applicable anti-vibration mountings.
5.10.2.1.6. Ensure that the unit is clean and free from any foreign material.
5.10.2.1.7. Install the drain line; slope it away from the unit, preferably Insulating ii. Install a trap in the drain line near the unit.
5.10.2.1.8. Install the refrigerant line. See Installation of typical refrigerant piping procedure.
5.10.2.1.9. Install electrical and control wiring in accordance with unit wiring diagrams, and local standards.
5.10.2.1.10. Install ductworks to recognize standards ensuring access panels for filters etc. are not obstructed.
5.10.2.1.11. Check the unit installation, clean the unit removing all work materials and debris.
5.10.2.2. Air Cooled Condensing Units:
5.10.2.2.1. Unpack the unit and move to final location taking care not to damage the unit. Remove shipping screws on wooden pallet and after removing the pallet refix the screws.
5.10.2.2.2. Condenser units shall be mounted on a concrete housekeeping pad, at a minimum of 100 mm {4″) above the floor or a minimum of 150 mm (6″) above unpaved ground. Air
cooled condenser unit shall be mounted on leveled surface.
5.10.2.2.3. Casings shall include doors to provide maintenance and removal access for all fans, motors, coils etc.
5.10.2.2.4. For proper drainage, the condensing unit must be raised from the mounting pad.
5.10.2.2.5. When installing the unit, allow sufficient space around the unit for air circulation, wiring, refrigerant piping, and servicing. The clearance must be as recommended by supplier- Zamil. Above the unit the condensing fans must not be obstructed for airflow clearance and maintenance.
5.10.2.2.6. Anti vibration pads (rubber-in-shear) or other vibration mounts {spring type) are recommended, especially for roof top installation and adjacent to occupied areas. The number of pads or spring isolators shall be as per Zamil recommendations.
5.10.2.2.7. Ensure that the unit is clean and free from any foreign material. Install the refrigerant line. See Installation of typical refrigerant piping procedure.
5.10.2.2.8. Install electrical and control wiring in accordance with unit wiring diagrams, NEC and local standards.
5.10.2.2.9. Check the unit installation, clean the unit removing all work materials and debris.
5.11. Exhaust fans:
5.11.1. All Exhaust fans shall be installed in accordance with SMACNA standard or equivalent.
5.11.2. The motor and its components shall be free of any debris or other materials which will obstruct the rotation of the pulleys.
5.11.3. Refrigerant Piping shall be carried out as per standard construction drawings and IFC drawings to suit site conditions.
5.11.4. The location of the exhaust fans shall be as specified in the approved IFC drawings.
5.12. Electrical Duct Heater:
5.12.1. All duct heaters shall be installed in accordance with SMACNA standard or equivalent.
5.12.2. The duct heater elements shall be free of any debris or other materials which will create combustion.
5.123. The duct heater elements shall be installed 100% along the air stream so that the air will flow to the elements.
5.12.4. An access door of 12″ x 12′(min.) opening shall be provided on each Duct heaters for maintenance.
5.12.5. The location of the duct heaters shall be as specified in the approved IF-C drawings.
5.13. Bleed fans/ Inertial Air Filter:
5.13.1. Bleed Fans
5.13.1.1. All Bleed fans shall be installed in accordance with SMACNA standard or equivalent.
5,13.1.2. The motor and its components shall be free of any debris or other materials which will obstruct the rotation of the pulleys. Refrigerant Piping shall be carried out as per standard construction drawings and IFC drawings to suit site conditions.
5.13.1.3. The motor and its components shall be installed in an accessible manner to provide way for maintenance. All Bleed fans shall be installed so to extract the sand from the sand trapping unit respecting the air flow as specified in the approved IFC drawings.
5.13.1.5. The location of the bleed fans shall be as specified in the approved IFC drawings.
5.13.1.6. Bleed fans shall be installed on concrete foundation or as specified in the approved IFC drawings.
5.13.2 Inertia Air Filter:
5.13.2.1 Inertia filter unit shall be installed in accordance with approved IFC drawings.
5.13.2.2 It shall be installed before the fresh air fan so that it collects the sand passing through it.
5.13.2.3 It shall be installed higher than the bleed fan so that the collected sands will be extracted easily by the bleed fans.
5.13.2.4 All inertial air filter units shall be installed in line with the fresh air ducting’s as specified in the approved FC drawings respecting the air flow.
5.13.2.5 All inertial air filter units shall be installed on substantial concrete foundation or as specified in the approved FC drawings.
5.13.3 Fresh Air Stack:
5.13.3.1. Fresh Air Stack unit shall be installed in accordance with approved IFC drawings
5.13.3.2 Location, orientation, elevation and conditions of AIR Stack conformed with Approved drawings.
5.13.3.3. All Air Stack units shall be installed on substantial concrete foundation or as Specified in approved shop drawing.
5.13.3.4 Installed sand trap Louvers are from the approved manufacturer and vendor with wire mesh or bird screen.
5.13.3.5 Air Stack & Components (including Coatings) are free of damage. Any damages are identified for Corrective & Preventive Action as required.