Installation of Air Conditioning Plants
PROGRAMME: A detailed programme for installation should be made and if the firm for carrying out the work is fixed, it should be discussed with him and targets finalized. This programme should at least decide dates for following events:
- Preparation of drawing.
- Approval of drawing.
- Receipt of equipment. Generally Equipment may come in parts. Fix dates for various components/materials.
- Site work, this again can be divided in various elements. Fix dates for few important activities.
This programme should be recorded and may be suitably displayed in plant room.
For installation, as now AC requirement i/c future expansion is known, the layout should be prepared. In case agency to carry out AC work is finalized, he should prepare installation drawings by visiting site. Drawing should indicate location of dampers, filters, heaters fire dampers, condensers, air inlet and exhaust needs of condenser, electrical panel, control and alarm panel etc. In case agency is not yet finalized, tentative layout should be drawn and it should be insured that adequate space is available for present as well as future requirements. Following points should be seen:
- Location of AC plant vis-à-vis area to be conditioned is acceptable or not.
- Adequate area is available for installation of package units keeping in view future requirements also if any.
- Proper space is available for installation of air-cooled condensers. Requirements for exhausting hot air from the condensers and inducting atmospheric air for cooling should be identified and conveyed to civil side for execution. Efforts should be to place condensers as near the package units as possible.
- Plant room door should be 1.5 m wide (in two panels) and 2.25 m in height. It should open outside. One panel can be for daily use, other panel will remain closed.
- Identify approximate opening size for supply air duct, return air, and fresh air and co-ordinate with civil sides to avoid modifications at a later date.
- Adequate clearance for maintenance and return air should be maintained. In front of package unit 1 m and on other sides 0.6 m clearance should be there.
The sizes of standard capacity PAC units are (W × D × H in mm):
Indoor: 950 × 660 × 1925 mm
Outdoor: 1 No 1230 × 625 × 940 mm
7 TR Kirloskar
Indoor: 1380 × 760 × 1600 mm
Outdoor: 1 No 1605 × 710 × 885 mm
7 TR Voltas
Indoor: 1400 × 900 × 1600 mm
Outdoor: 1 No 1200 × 600 × 885 mm
7 TR Fedders Lloyd
Indoor: 1595 × 660 × 1925 mm
Outdoor: 1 No 1830 × 740 × 1010 mm
10 TR Kirloskar
Indoor: 1220 × 750 × 1950 mm
Outdoor: 1 No 2175 × 715 × 1030 mm
10 TR Kirloskar
Indoor: 1795 × 660 × 1925 mm
Outdoor: 2 No 1230 × 625 × 940 mm
CHECK LIST FOR SMOOTH PROGRESS.
- Check that the areas to be air-conditioned are as per design, if any changes are noticed, decide the course of action.
- All requirements e.g. some modifications in building, storage space etc; which come to light during site inspection should be noted and brought to notice of concerned unit for further necessary action. Keep watch so that these items are timely completed.
- Check cut outs required for electrical cables from substation to main electrical panel and condenser.
- Check water input connection for humidifier and drain connection for discharging condensate.
- Check opening for supply & Return air, ensure these are provided.
- Identify and make arrangement for lockable storage space which may be required by AC firm.
- Examine the route for bringing the equipment up to the storage space and to r each the final destination. Ensure that the route is feasible. Any changes required on this account should be sorted out.
- Check that light fittings in the package room will not interfere with erection of duct/plenum.
- Check that light and power plugs and also control switches are not coming in wall where insulation may be required, that is it is not on external walls.
- Plan provision of power supply for package units so that same is available as required by the programme of commissioning of AC system.
- Arrange limited power supply to meet erection requirements.
- Mark the position of package units, humidification units, electrical panels, heaters panels, control as well as ducts and plenum as shown in the approved plan on the floor. See if any problem is likely to arise during actual installation. Ensure 1 m clearance in front of electrical panel.
- Any correction required should be carried out in advance i.e. before actual installation of equipment.
- Mark wall openings for fresh air, return air, supply air in the plant room.
- Ensure clearance for working on the condensers, adequate opening for atmospheric air for cooling condensers and adequate opening for hot air exhausted from the condensers directly to one atmosphere.
- Decide the route of condenser refrigerant piping and power cable from packages and also decide the height of cable tray/ refrigerant piping tray.
- Examine the supply air opening on the false floor tiles with required to the equipment lay out.
- Examine return air opening. These should come directly above the racks for E-10-B installation. For other types of exchanges, check if there are any recommendation on this aspect.
- Ensure sealing of all floor/ceiling openings for power cables, telephone cables etc to avoid leakage of supply air, return air.
- Check motors and equipment for alignment.
- Check equipment for effective earthing.
- Check all terminals for tightness.
- Check operation of under voltage / no volt coil.
- Check Insulation resistance of all motors and cables.
- Check belt tension, availability of belt-guards and abnormal noise.
- Check bearings for proper lubrication and overheating.
- Check direction of rotation of all motors.
- Check availability of water, water circulating system and water softening plant, if any.
- Check operation of all protective devices including LP and HP cut-outs.
- Check suction and delivery pressures and insure that they are within design limits.
- Check setting of thermostat in AC area and return air.
- Check fresh air quantity and lock fresh air inlet after setting.
- Check setting of humidistat.
EVACUATION AND DEHYDRATION.
- Before charging the system with refrigerant, it is absolutely necessary to remove moisture. For, moisture causes serious damages to the entire refrigerant circuit.
- Removal of moisture is termed as dehydration. This is done by creating very high vacuum in the refrigerant circuit by means of a two-stage vacuum pump. The vacuum is of the order of 100 microns(Hg.)
CHECK LIST FOR CONTROL OF WORKMANSHIP
CONTROLS OF MATERIALS.
The objective here is that the materials used in the execution of job are of proper quality. For judging proper quality, materials can be divided into two categories.
- The first group is about which agreement specifies some identification parameters for example, catalogue number, name of brand etc., such items should be checked according to such identification marks.
- The second group is that where identification marks are not available. Here we have to supply our judgment and the guiding principle is that it should be one of the good quality products available in the market.
Is approval and reputation of the manufacturer can be the guiding parameters. We should not allow cheap alternatives when better things are available in the market, only because no specific make(s) are mentioned in the agreement. The agency is committed to do a good work and hence bound to use quality makes out of the range of makes available in the market.
The practical way to control material is that we should open a register for the work. If already some register has been opened for the work some pages may be earmarked for materials. In this register enter each and every material that is brought to site by the contractor. And against each item state whether you approve it or not. In case of doubt, consult Engineer-in-charge. it is not necessary that you should enter in the register materials as they arrive, because this is not always possible. However, this should be done at the earliest and should be one of the activities to be performed during your site visit. The stores of the agency should be inspected for this purpose and information should be collected from the workers regarding materials that have come to site. This way you will get an opportunity to react to every material brought to site and thus ensure that only proper materials are used in work.
Read the agreement item and also relevant specifications and ensure that items executed/being executed are as per agreement and specifications. If not, note down the differences and bring to the notice of Engineer-in-charge for further necessary action.
See that items not approved are replaced by bringing them to the notice of the agency doing the work. Item requiring decision should be stored out at the earliest.
- Ensure in case of evaporator that thickness of tubes and diameter are as per specifications/offer.
- Ensure that installation is vibration free. Use rubber pads & 75 to 100 mm C.C foundation.
- Check for abnormal noise.
- Check that all the devices provided are functional. Alarms, meters interlocks and safety devices are performing their desired task. This should be done by creating artificial conditions.
- Ensure that there is nothing that is damaged in the installation.
- Ensure that refrigerant piping is on trays and free from possibility of mechanical damage. See under condenser also regarding refrigerant piping.
- Ensure that wiring is neatly done with proper size of cables & no loose connections.
- Gauges mounted should be free from vibrations.
- Check for loose/damaged fins in evaporator.loose and damaged fins should be rectified.
- Ensure that plant room is air tight and no leakage takes place from this room to non air-conditioned areas.
- Doors provided should close properly.
- Any opening should be sealed.
- Check drain pipe connections and ensure that condensed water is discharged without spilling in room.
AIR COOLED CONDENSERS
- Condenser needs atmospheric air for cooling and discharges hot air to the atmosphere. Ensure that discharged hot air does not get mixed with air drawn for cooling. Also coils are in direction of wind.
- Installation should be vibration free. Rubber pads be placed below the unit.
- Check for abnormal noise.
- Ensure that refrigerant piping is carried out in such a manner that it is not liable for mechanical damages, Avoid floor. For trays ensure 210 cm height from floor. Pipes should be clamped and not left loose.
- Ensure that electrical wiring does not have any loose connections and is neatly carried out.
- Also ensure that it is not liable for mechanical damage.
- Check that cables/swatches do not get hot when the system is in use.
- In case-condensers are installed adjoining to package units room, ensure that no leakage of air to package units is possible from the condenser enclosure.
- Check condensers fins for looseness and damage.
- Check the air quantities and ensure that they are as per offer.
- Ensure proper functioning of condenser for interlocking with compressor.
- Check gauge of sheet metal.
- Reject GI sheets having excessive water mark or corrosion mark or other damages.
- Nut,bolts and washers should be zinc plated.
- Check that the ducts have been stiffened by cross breaking at 300 mm centers for ducts having a maximum side of 600 mm and for ducts having size bigger than 600 mm it should be 150 mm center to center (See Figure 16 duct fabrication at the end).
- Self taping screws shall not be used.
- Insulated ducts need not be cross broken.
- Ensure that flanged joints are used at intervals not exceeding 2.5 m.
- All flanged joints shall have 6mm thick felt lining between flanges.
- Check that volume control dampers are provided as per drawing.
- Check that fire dampers have been located as per approved drawings.
- Check that removable panel for access to heaters are provided.
- Angle iron supports (40 × 40 × 6 mm) for ducts are placed at distance of not more than 2.5 m.
- 6 mm Neoprene or other vibration isolation material should be provided between ducts and supports.
- Check that double canvas cloth 100 mm long between AHU and duct is provided with zipper arrangement.
- Check that sheet asbestos mill board of 6 mm thickness is applied to interior of duct where heaters are located for a distance of 300 mm on each side of the heater.
- Check that vapour barrier is not more than 250 gauge of polythene sheet wrapped on both sides of insulation.
- In case of E10-B bottom supply air duct should not touch the floor, raise it about 50 mm above the floor.
- 6 mm thick asbestos sheet of size more than 1.2 m × 1.2 m should not be used. Bigger sheets should be cut before use.
- Each sheet should be screwed separately on all sides.
- Check for loose connections, local heating, abnormal noise and foreign material in panel.
- All holes should be plugged so that insects and dust do not get entry in to the panel.
- All items installed are performing their functions smoothly i.e. switches can be made ON and OFF, ammeter, voltmeter read the values, relays are functional. Check that safety devices are functional. These items have to be tested by creating fault conditions at site.
- Check that sign writing is not only neatly carried out but provides meaningful information also.
- Check for clearance of live parts from body / live parts. It should be minimum 28 mm between live part and body and 32 mm between phases.
- Check for rigidity of supports provided for bus bard.
- Check bus bar size. Current density should not exceed 130 A/cm².
- Tap off connections up to 100 A can be made with PVC wires, for higher currents, this should be with solid sleeved conductors.
- Starters/contractors are of adequate size, check as per chart available at the end.
- Check that main cables are properly supported and are not causing any strain on the bus bar where end connection is made.
- There should be at least 1 m space in front of the panel and less than 230 mm or more than 750 mm behind the panel depending upon working is required from behind or not. In case panel can be fully operated and maintained from front, there is no need to leave space behind.