Guide to Run Air Conditioner Economically and Safely

Improper setup of air conditioner either can lead to reduced life of the machine or reduced life of the owner. Although the former fate is more common, later fate not just rare across the globe. Manufacturers of air conditioner like heavy duty electrical system will assume that the owners are knowledgeable enough to arrange technicians for correct electrical setup and heat insulation. An air conditioner unit not really fully consumer grade product – installation does need expert technicians both from electrical & HVAC field. Warranty will get void if the technical points are not maintained. We expect the owners to have own multimeter and clamp multimeter for regular checking of load & basic troubleshooting. Owners who are not used with basic electrical & electronics works should not use the mentioned instruments themselves but involve a technician for a more frequent checkup.

Table of Contents 1 Introduction 2 Required basics of HVAC 3 Required basics of civil engineering 4 Required basics of electrical engineering 5 Conclusion

 

Required basics of HVAC to know

 

Type of AC
 

There are several types of air conditioner units such as portable air conditioner, window air conditioner, mini-split air conditioner (or split AC), floor mounted air conditioner (or tower AC), ceiling mounted air conditioner (or cassette air conditioner). The basic technology used in them is century old. Each type of air conditioner has own use case.
Portable AC is suitable for the name it indicates – small rooms of hostels, dormitory or as an add-on unit at the home. Portable AC usually is of less than one-ton capacity and it is quite consumer friendly. Window AC is suitable for the places where an installation wall is available. It is a consumer-friendly next to the portable AC. Both portable AC and window AC requires minimum knowledge of the installer/technician as well as servicemen. Window AC can be 3 star rated or 5 star rated. The compressor of window AC can be traditional or inverter type. Although split AC uses the same technology that of window AC, as the units are split and connected via insulated copper tube, the installation and maintenance part not possible without good training.
Planning the installation of split AC, tower AC and ceiling mounted AC demands a person who is knowledgeable around aero-dynamics of HVAC.
There are mainly 5 types of air conditioner compressor that are commonly used in the industry:

1. Reciprocating
2. Scroll
3. Screw
4. Rotary
5. Centrifugal

The inverter air conditioning became more popular due to its energy savings approach. The advancement in electronics has enabled to use microcontroller and IGBT modules to drive the compressor DC motor. The speed of the compressor motor can be varied by using the variable frequency drive. Changing the frequency changes the speed of the compressor.

 
Tonnage of AC
 

It may not be easy to decide the spot of a 1.5 ton split AC unit over a 10 feet height wall with concealed wiring and concrete reinforcements. The too low height of installation may demand heavy duty machine, too high installation may need split AC with additional air intake window on the side or at front. Also, 2-way swing is suitable for an area which is equally broader that of split AC indoor unit. It is a rough working calculation – if an indoor split unit is 5 feet wide, it is suitable for placing in the middle of a wall of 15 feet breadth. Such installation will not need additional blowers to re-distribute the cold air. Broader wall with split AC tonnage over 1.5 ton demands expert’s guidance for optimal cooling. 4-way swing mechanism broadens the area to be cooled.
For an average living room, one 4-way swing split AC with a minimum 3-star rating of tonnage 1.5 ton above will be suitable. There are some models of split AC with heavy-duty blowers to cover 35 feet length.
A common mistake done to calculate the required tonnage of AC is a simple calculation of the carpet area. Rooms are occupied with things which are air-tight such as wooden furniture. They reduce the area but may interfere with the air dynamics. A room of 300 square feet carpet area with a height of 10 feet may not need a 3 ton AC. One 1.5 ton split AC may be sufficient if there is a lot of furniture made up of non-conductive materials. It sounds great money saving tip! Not exactly. That calculation takes it granted that the number of peoples will not be more than 3.

1. Higher the number of peoples in the room more will be the need for higher tonnage.
2. Higher the time door will be opened, more will be the need for higher tonnage.
3. Uninsulated West side facing top floor will need more tonnage.
4. Higher tonnage yields faster cooling.

 

Lesser tonnage will force the unit to more load inviting shorter life-span. Over tonnage is safer than under tonnage. If you need lesser tonnage, insulate the room, divide it by air-tight partitions. One higher tonnage unit is more economical than multiple lower tonnage machines. Shops, showroom mall are checked by the experts for multi-unit installations.
1.5 ton and above split AC units with inverter technology will save electricity more in a longer duration of a run per day. Inverter technology “slows down” the compressor to lower tonnage and finally shuts down the compressor. It is a myth that inverter technology makes the compressor always running. The microcontroller makes it more sophisticated in “braking”. 8+ hours run of a 1.5 ton and above split AC unit with inverter technology inside a 130 cubic feet room will keep the electricity bill lower when the temperature is set above 25 degrees or above. Inverter technology not required for the rooms which will need hardly 1-3 hours run. Inverter technology essentially saves electricity after 4-6 hours run by “intelligent rev & brake”.
5 star rated inverter AC is suitable for the bedrooms. Commonly peoples need air conditioning 1 PM to 6 PM and at night. Rest of the time if spent at living or dining, they can be managed by using lower tonnage AC units for making the room “just comfortable”.

 
Run of copper tubing
 

Split AC is officially specified for the supplied length of copper tube i.e. around 10 feet. Although inverter AC compressors can handle the change of direction (bent in layman’s terminology), tubing length up to 25 feet, a long run of exposed copper tubing to sun invites challenges.
Split AC works best when indoor and outdoor units are exactly opposite of the wall or just on the top of it (like on the roof). The compressed gas passed through the tube also roll some oil from the compressor. In the case of inverter AC compressors, the rolled oil easily comes back more easily when basic physics of fluid mechanics is helped. This is the reason why installers usually have seen to install the units at typical locations at outdoor. The insulated copper tube exposed to sun, air, birds is vulnerable to destruction with time. Pipe insulation hose separately sold, so as a soft copper tube.
Your technician/servicemen will periodically check and suggest any need for replacement of insulation and/or copper tubing. Superior quality pipe insulation sold separately. China (like any other things) also sell insulation.

 
Gas leak & refill
 

Split AC on long run may face leakage inviting need of complete refill or top-up refill (depends on gas).

 
Servicing
 

4 monthly servicing is suggested for cleaning the condenser fins, fan blades, checking electrical part & cooling. Servicing can be wet or dry. Wet servicing is required for cleaning heavy dust collection. It is a myth that split AC does not need servicing. Underserviced AC may catch fire, leak gas, explode or consume higher electricity. Owners should clean the filter every month by dipping them in to warm water. Usage of soft detergent may be practical to remove heavy dust collection. In case of split AC, owners should clean the outside of the indoor unit with a moist cloth, if possible the outdoor unit clean the outdoor unit keeping the units unplugged.

 

Required basics of civil engineering to know

 

Most of the required basic civil engineering part is handled by the installer. The owners should ensure the slope of the holes made to be outwards, monitor the water drainage pipe. Window AC units quite erratically discharge water from the bottom of the unit which may invite the need of using drainage tray and tubing. All holes created by the installer must be sealed properly.
A 1.5 ton split AC with inverter technology may drain 10-15 litres water per day when ran in cool mode. The discharged water is like mineral water and unmanaged water discharge falling on concrete may invite a burst of the iron bars over time.
The rooms to be air-conditioned supposed to sealed from the hot air of outside, dust particles and heat. Proper selection of paint, floor, carpet/floor and window design supposed to address the above issues. A double layer window with aluminium shutter window inside significantly reduce dust and heat load in the room. Gaps at the bottom of the doors should be addressed by the usage of insulation for this purpose. Once the arrangements are done, the need for servicing in a shorter time is lower.
Split AC units preferably are avoided to face the sun all over the day i.e. West facing side. Roof-top is one of the secure places of installation of the outdoor units of split AC. When installing over outside wall, it is best to ensure industrial standard design to safely climb, stand, sit to inspect and service the unit. At many places, maintaining these standards made mandatory for the high-rise building to ensure workplace safety. Installers & servicemen must report a dangerous installation point to their colleagues seeking opinion to reach the unit. No installation, servicing should be started after the sunset to ensure maximum safety. Installation, re-installation & servicing split AC has a variable degree of unavoidable risks. The service centres should explain the novice owners their liabilities.

 

Required basics of electrical engineering to know

 

It is the supplier of electricity who will handle the selection of proper meter, the proper diameter of copper wire for the required higher load. It is the owner’s duty to employ a certified technician to ensure proper wiring and electrical safety from the point of wire where their liability ends.
Usually, 10 square CM wires used by the supply for higher load. At the next point, an old style “main switch” still used, followed by modern MCB units for each room and connections. Using 10 square CM copper wire for the whole house is not cost effective. From MCB, the connections are made in a star configuration. This configuration keeps the other wiring safer and easily serviceable. Each connection to each air conditioner should have own MCB and amperage limited according to the manufacturer’s specification. Using a 20 amp MCB for an 8 amp AC unit makes the MCB partially functioning. An 8 amp rated machine should trip the MCB upon reaching 10 amp need.
Next, is the connection from the MCB to the air conditioner unit. At this point, usage of DB metal plug and socket is recommended for having secure firm contact. Also, the DB metal plug and socket have porcelain as material (in contrast to heavy duty plugs of household design with plastic casing) which works as a better insulator. Proper functioning of the MCBs in the line of each air conditioner should be checked on a regular basis. We suggest to use clamp multi-meter for regular checking of load at least once a month and maintain a log file.
In the developing countries outside the metro cities, supply voltage often fluctuates and there is little surge protection. A surge protector is an added low-cost solution to protect the devices from electrical adversities raising out of natural calamities. However, much-varying voltage demands costly voltage stabilizer to keep the supply to the AC unit consistently at 220-230V.

 

Conclusion

 

Monitoring installation and maintenance of air conditioner unit demand a minimum working knowledge of electrical devices which is expected from any educated being. Apart from the technicians & engineers, there are enough number of reliable free resources on the internet to provide basic knowledge to avoid accidents. Most of the manufacturers notify the users lesser than the required. However, they may make the warranty void upon the usage of unregulated voltage resulting damage to the unit. “Stabilizer free operation” mostly a marketing gimmick and least to do with damage of the circuit.

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