INSTALLATION OF AIR CONDITIONING SYSTEM ⋆ Archi-Monarch

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The installation of an air conditioning system typically involves several steps. Here is a general overview of the process.

Installation of Air Conditioning System

1) Installation of Chiller

The chiller shall be mounted on a reinforced cement concrete / structural foundation and shall be adequately isolated as per manufacturer’s recommendations against transmission of vibration to the building structure.
For open type, special attention shall be paid to the alignment of the drive and driven shaft; final alignment shall be checked at site in presence of the contractor, using a dial indicator.
Compressor and motor sole plates, anchor bolts, sleeves and necessary vibration isolation pads shall be provided with the chiller.
All controls and switch gear shall be tested for proper functioning and set at design values.
These shall be mounted within a panel, installed so as to permit enough space to move around the machine, and to freely operate the door of panel.

2) Installation of Pump

The pump base frame shall be mounted on concrete block which in turn shall be mounted on machinery isolation cork or any other equivalent isolation material.
More than one pump set shall not be installed on a single base or on a single cement concrete block.
Foundation bolts where required, shall be embedded correctly.
Before the bolts are grouted and the coupling bolted, the base frame level shall be checked before proceeding with work.
The pump motor shall then be mounted on base frame, alignment checked, and shall then be connected to the pump with flexible coupling and with guard, both for the condenser and chilled water pumps.
The insulation for chilled water pump shall be carried out in a manner so that it allows maintenance of the pump without causing damage to the insulation.
After installation of the complete system and before testing, the pump shall be lubricated in strict accordance with the manufacturer’s instructions.

3) Installation of Cooling Tower

The cooling tower shall be mounted on a set of four or six numbers of reinforced cement concrete pillars (structural foundation) as per manufacturer’s recommendations.
Height of these pillars shall be not less than 1000 mm, actual height is decided at site as per space required to install a pot strainer below the water level in cooling tower sump, drainpipe and valve for complete drainage of sump, and to permit maintenance of slab upon which structural foundation is installed.
Cooling tower should be located at a well-ventilated place, preferably on the terrace of the building, in consultation with the structural consultant.
Dynamic structural loading on the terrace shall be considered.
Cooling tower shall be installed in such a way that its dynamic load is transferred directly to the building structural columns, for which necessary mild steel I-section may have to be provided.
Epoxy coating is required for these mild steel I-sections.
Suitable thickness of vibration isolation pads shall be placed between the tower and the I-sections to avoid transfer of vibration to building structure.
Sufficient space shall be left all around the cooling tower support structure for efficient operation of the cooling tower.
When cooling tower is installed at ground level, contiguous to the utility services block, great care has to be exercised to prevent users and visitors from coming in close proximity to the cooling tower.
This is necessary to avoid their exposure to legionellae bacteria which can hibernate in the cooling tower sump, if operator does not follow strict instructions for regular bleed-off and chemical treatment of condenser water.

4) Installation of Air Handling Unit (AHU)

a) Type – 1

Floor mounted air handling unit is generally installed on a set of precast PCC blocks to raise it off the mounting surface to permit easy drainage of the AHU drain pan and cleaning of the mounting surface.
A set of 4 or 6 numbers of 200 mm × 200 mm × 200 mm blocks are generally used for AHUs up to capacity of 10000 m3/h airflow, and 6 or more 300 mm × 300 mm × 300 mm blocks for higher capacity AHU.
It is essential to provide floor trap in the AHU room for disposal of condensate which accumulates in the drain pan during operation of AHU.
AHU room floor should slope in the direction of floor trap to avoid the accumulation of water in AHU room.
Also, the slope of the drain pan should be checked in the direction of drainpipe connection, to ensure zero retention in the drain pan, precluding possibility of legionellae bacteria hibernation.
The condensate drain piping shall be connected with U-trap of the floor drain to avoid odour carry over with the return air.
AHU location shall be marked on the AHU floor as per approved shop drawings/manufacturer’s details.
Co-ordination with contractors for civil works and other services shall be checked prior to installation.
AHU shall be assembled at site and installed on vibration isolation pad placed upon each PCC block, as per manufacturer’s recommendations against transmission of vibration from AHU to the building structure.
Easy accesses and sufficient clearance shall be ensured for servicing and maintenance, that is, for cleaning of filters, maintenance of strainer/valve packages, tightening of fan belts, and repair as well as possible replacement of fan motor.
Duct flexible connection made of fire-proof canvas, shall be fixed on air outlet of the AHU, and if possible, also in perpendicular direction in main ducts within AHU room, to avoid vibration transmission along the ducts beyond the AHU room.
The valve package and piping connections shall be completed as per approved shop drawings.

b) Type – 2

Installation of ceiling suspended air handling unit shall be done with rod and fasteners as per the procedure stated above, barring the PCC blocks required for floor mounted AHU, and that insulated condensate drainpipe shall be laid in slope within ceiling space terminating into the U trap of the nearest floor drain.

Note –

Since the AHUs have the tendency to vibrate, both floor mounted and ceiling suspended AHUs shall be isolated from the structure by suitable rubber or spring based isolators.

5) Installation of Air Washer Unit (AWU)

Air washer unit (AWU) components are similar to those of AHU, except for water spray section with in-line recirculation pump, which replaces the cooling coil.
Installation of AWU shall follow the same steps as described above for AHU.
Ceiling suspended AWU is not recommended.

6) Installation of Axial Fan

Axial fan is manufactured in vane-axial and tube-axial configuration, and is generally mounted in-line, suspended from ceiling.
Special care is required for its mounting to minimize noise and vibration transmission to the structure and also to the connecting duct work.
The fan is generally mounted on two numbers of mild steel channels of size 100 mm × 50 mm × 5 mm, welded onto mild steel plate of 6 mm thickness, finished with 2 coats of red oxide and one coat of epoxy-based enamel paint. Support rods for hanging the plate shall be cut and trimmed after finalizing the levels; extra length of 25 mm of support rods should be left for final adjustments.
Burrs and sharp edges should be removed before applying finishing coat of paint.
All necessary accessories, as below, shall be provided for proper installation:

Vibration isolators for the axial fans;
Double canvas connection (of fire retardant material) at the outlets of each fan;
Acoustic silencers at inlet and outlet of the fan as per manufacturer’s instructions; and
Bird screen for the protection from extraneous elements, specially at fresh air intake and at exhaust outlet to outdoor.

Axial fan shall be installed in a manner so as to allow easy maintenance of the fan, its accessories, and easy service and possible replacement of fan motor.
Field balancing shall be done.
Upon completion of installation, capacity of axial fan shall be measured by an anemometer.
Power consumption shall be computed from measurements of incoming voltage and input current.
Measured values shall conform to the data given by the vendor in technical submittal.

7) Installation of Ducting Works

The material and constructional requirements for ducts shall conform to the accepted standard.
The installation of sheet metal duct work for air distribution and also its associated items, such as, air outlets and inlets, fresh air intake and smoke/fire dampers are covered below.

i) Duct support and hangers

Supporting details for low pressure rectangular ducting system are given below:

Supporting details for high pressure rectangular ducting system are given below

Installation of other types of ducts and supports may be decided in consultation with the specialist structural designers.
However, all safety and performance criteria in accordance with this Section shall be complied with in all cases.

ii) Damper

Volume control damper shall be provided at the junction of each branch duct with main duct.
Dampers shall be 2 gauge heavier than the gauge of large duct but should not be less than 20 gauge and shall be rigid in construction so as not to flutter with the passage of air.

iii) Access door

Access door shall be provided in duct before and after any equipment like in-line fan installed in duct.
Access door shall also be provided before every smoke/fire damper location.
Access door shall be fabricated of the same material as the duct work and shall have minimum two hinges.
Hinges shall be zinc plated and pins shall be of brass. Access doors shall be of minimum 305 mm × 305 mm size.
At least two heavy solid fasteners and a brass handle shall be provided for each door.
A continuous neoprene rubber gasket shall be fixed with adhesive to the opening frame.

8) Installation of Piping Works

Design, choice of materials, and the installation of chilled water/condenser water/drain water pipes, pipe fittings and valves shall conformed to relevant Indian Standards and shall meet the requirements of pressure rating for the system.
Chilled/condenser/hot water pipes of sizes up to 150 mm shall be heavy class, ERW mild steel black pipes conforming to the accepted standard and those of sizes above 150 mm shall be ERW/SAW pipes of Grade 330 conforming to the accepted standard.
Piping shall be properly supported on, or suspended from, stands, clamps, springs, hangers, as required at site.
Design of all the brackets, saddles, anchors, clamps and hangers shall be as per requirement identified by the system designer.
All pipes within HVAC plant room shall be supported off the floor of the plant room, and rest from the ceiling, with engineered support structures made of pipes and channels, with pipe always resting on the necessary high density PUF/wooden haunches.
Minimum requirements in respect of support details, for horizontal and vertical chilled water pipes with mild steel channel and angle sections, are given in Table below.

The recommended spacing between supports for various pipe sizes are given below.

All pipe supports shall be of steel, coated with two coats of anti-corrosive paint and finally finished with epoxy paint.
Where pipe and clamps are of dissimilar materials, a gasket shall be provided in between.
Vertical pipes passing through floors shall be parallel to wall and should be straight to wall duly checked with plumb line.
Wherever pipes pass through the brick or masonry/slab openings, the gaps shall be properly sealed as per Fire and Life Safety.
Wherever insulated pipes are installed, pipes should be supported in such a way that no undue pressure is exerted on the insulation material.
Piping layout shall take due care of expansion and contraction in pipes, and shall include expansion joints, where required.
All pipes shall be accurately cut to the required size in accordance with relevant Indian Standards, edges beveled and burrs removed before laying.
Open ends of the piping section shall be closed as the pipe is installed to avoid entrance of foreign matter.
Where reducers are to be made in horizontal runs, eccentric reducers shall be used for the piping to drain freely.
In other locations, concentric reducers may be used.
Auto purge valves shall be provided at all highest points in the piping system for venting air.
Air valves shall be 15 mm pipe size with screwed joints.
Discharge from the air valves shall be piped through an equal sized mild steel or galvanized steel pipe to the nearest drain or sump. These pipes shall be pitched towards drain points.
Drainpipes shall be provided at all the lowest points in the system, as well as at equipment where leakage of water is likely to occur, also to remove condensate and water from pump glands.
The drainpipe work can be carried out with threaded joints or simply welded.

9) Installation of Insulation Works

Fixing of thermal/acoustic insulation of ducts, pipes with valves and equipment room shall be done in accordance with given below.

i) Material

Selection of material shall be as per design requirement, such as,fibre glass, closed cell flexible elastomeric foams, expanded/extruded polystyrene (EPS/XPS) and polyurethane foam (PUF).
The guidelines for insulating with fibre glass are given below; for other insulation materials, manufacturers’ recommendations for installation should be followed.

ii) Thermal insulation of duct

Surface of duct, on which the external thermal insulation is to be provided, shall be thoroughly cleaned with wire brush and rendered free from all dust and grease.
Then, two coat of cold-setting adhesive compound (environment friendly), should be applied over the duct surface.
The thermal insulation material should then be wrapped around the duct with aluminium facing on outer side.
Joints of insulation should be properly sealed with either same type of material or aluminium tape of 50 mm width on all longitudinal/transverse joints.
Finally PVC straps should be fixed at suitable interval to ensure that the insulation is properly fixed with the ducts.
The insulation should then be covered with 0.63 mm × 19 mm galvanized iron (GI) wire mesh netting on the outside of the duct, where it is exposed to the weather and should be additionally covered with either a layer of tar- felt, or two coats of 10 mm thick sand cement plaster.

iii) Acoustic lining of duct

Acoustic lining of duct should be carried out as follows:

The inside surface of duct on which the acoustic lining is to be provided should be thoroughly cleaned with wire brush and rendered free from all dust and grease.
The material to be used for duct lining should be 12/25 mm thick resin bonded fibre glass rigid board having a density of 48 kg/m3. The board should be fixed inside the duct using suitable adhesive and covered with fibre glass tissue paper.
The insulation board should then be covered with 0.5 mm thick perforated aluminium sheet with at least 20 to 40 percent perforation.
The insulation board and aluminium sheet should be secured with cadmium coated bolts, nuts and cup washers/steel screws.
Finally, the ends should be sealed completely, so that no lining material is exposed. The lining of initial length of the duct may have to be done as per the requirement at site. Alternatively, open cell flexible elastomeric foams or fire retarding foam board panels, specially formulated to attenuate noise may also be used. These should be fixed inside the duct with special eco-friendly cold- setting adhesive compound.

iv) Acoustic lining in equipment room

Acoustic treatment in equipment room to prevent noise transmission to adjacent occupied areas should be provided on the walls and ceiling of equipment room with acoustic lining of thermal insulation material. The process should be as below:

Wall/roof surface should be thoroughly cleaned with wire brush.
A 610 mm × 610 mm framework of 25 mm × 50 mm × 25 mm or 50 mm × 50 mm × 50 mm ‘U’ shape channel, for 25 mm or 50 mm thick acoustic lining respectively, made of 0.6 mm thick galvanized steel sheet should be fixed on to walls leaving 610 mm gap above floor (to prevent damage from flooding) by means of wall plug/screw anchors in walls. Similar framework should also be fixed on ceiling by means of dash fasteners.
Resin bonded glass wool/mineral wool as specified, cut to size should be fitted in the framework and covered with fibre glass tissue paper.
Surfaces should be finished by covering with 0.5 mm thick perforated aluminium sheet having perforation 20 to 40 percent with brass screws.
All horizontal and vertical joints should be covered with at least 25 mm wide, 1 mm aluminium strips held in position by steel or brass screws.

v) Insulation of CHW/HW refrigerant pipes

Pipe insulation material should be EPS/XPS/PUF/ closed cell flexible elastomeric foam/fibre glass as per requirement, specified with suitable density and thickness.

Adhesive used for setting the insulation should be non-flammable, vapour proof, cold-setting, eco-friendly compound.

Generally, pipe insulation material is available in pre-moulded pipe insulation sections, which should be applied to the pipe surface and sealed as described below.

The pipe to be insulated should be cleaned thoroughly with steel brush for removing dirt, rust and grease.
A coat of zinc chromate primer and two coats of cold setting adhesive compound should be applied on pipes.
Insulation of specified thickness should be fixed tightly and all joints should be sealed with adhesive compound.

The insulation should then be finished as per the specific requirement of the site, as given below:

Inside the building

Insulation over the pipe work exposed in the building should be finished with specified thickness of aluminium sheet cladding, over a vapour barrier, with 50 mm overlap and tied down with lacing wire.

Outside the building

Insulation over the pipe work exposed to weather should be finished with vapour barrier, and 12 mm thick cement- sand plaster in two layers of 6mm thick each, followed by curing of minimum 48 h.

Buried pipe insulation

For pipes outside the building and laid underground, the insulation should be covered with suitable gauge polythene faced hessian, (the polythene facing outward), with 50 mm overlap.
All joints should be sealed with bitumen.
A layer of 0.50 mm × 20 mm GI wire mesh netting should be provided over it is butting all joint, and it should be laced down with GI wire.
A 20 mm thick cement-sand plaster (1:4) should be provided in 2 layers of 10 mm thickness each and should be waterproofed by applying hot bitumen and fixing tar-felt over the plaster.
It should be finally finished with a coat of hot bitumen.

Pump insulation

Chilled water pump should be insulated to the same thickness as the pipe to which they are connected, and application should be same as above.
Care should be taken to apply insulation in a manner as to allow the dismantling of pumps without damaging the insulation.

Insulation of valves and fittings in chilled water line

All valves, fittings, strainers, etc, should be insulated to the same thickness and in the same manner as for the respective piping, taking care to allow operation of valves without damaging the insulation.

It is important to note that air conditioning installation should only be carried out by a qualified and experienced professional. They will ensure that the system is installed safely and correctly, and will be able to advise on the best system for your needs.