How to Choose: Air Conditioner

Related Posts
1 Choosing an Air Conditioner
2 Energy Saving Tips for Air Conditioners
3 Installation & Placement of Air-con Units
4 Air Conditioner Cooling Algorithm

Basic Considerations
Inverters or Non-Inverters?
Some sales people will tell you that aircons using non-inverter technology are more reliable and/or cheaper to maintain and repair than inverter aircons. Or that R22-based aircons cost less to maintain because the R22 refrigerant is cheaper to refill than the new R410A refrigerant.

Don't believe them.

Inverter technology today is highly advanced and compressors with inverter operate more efficiently and at lower energy costs. Inverter air-cons are therefore more efficient in energy utilization and saves you money, an important consideration as oil prices and electricity rates continue to rise. Rather than repeat what the experts are saying, I'll give you the links so you can learn why you should buy aircons using inverter technology:

R22-based or R410A-based Aircons?
This is a no-brainer: go for the newer R410A-based aircons. Why? Simply because whether you like it or not, R22-based aircons are being phased out! The dealers

know that, and whether they admit it or not, they have to unload R22-based aircons on unsuspecting and ignorant consumers, otherwise they will incur huge losses on unsold old stocks. So they tell you half-truths like "...oh, the R410A types are more expensive to refill... R410A-aircon costs more to repair.. etc, etc..."

Sure, they may be more expensive to refill initially, but as time goes on with the phasing out of R22-based aircons by 2015, it will be prohibitively expensive (or even impossible) to get R22 liquid refrigerant for your R22-based air cons!

So don't be conned!

Energy Efficiency
Of all the major appliances in the home, aircons and refrigerators consume the most energy in the monthly electricity bill. Half to two-thirds of the energy consumption of a typical household in Singapore goes to operating air-conditioners and refrigerators, hence households are urged to choose energy efficient appliances when buying such goods. According to the National Environment Agency, a household choosing a 3-tick rather than a 1-tick air-conditioner can save about $500 annually through reduced electricity consumption.

The Tick Rating is defined by the NEA as follows:

Air-conditioners

Type	Minimum COP 100%1 (W / W)
No. of Ticks	0	1	2	3	4
Casement, window, single-split (non-inverter)	<>	> 2.5	> 2.78	> 3.2	N/A
Multi-split (non-inverter)	<>	> 2.64	> 2.92	> 3.34	N/A
Split type (inverter)2 COP100% Weighted COP 3	N/A<>	N/A> 2.64	N/A > 2.92	> 3.06 > 3.34	> 3.34 > 3.76

¹ COP _100% is defined as the ratio of total cooling capacity to effective power input at full load cooling capacity
² For split (inverter) type air-conditioners, the model shall meet both the minimum COP _100% and weighted COP³ Weighted COP = 0.4 x COP _100% + 0.6 x COP _50%

Electrical Issues
Older flats built by the HDB have a limitation on the amperage of the aircons that can be installed. My flat has such a limitation, and the aircon load is limited to a maximum of 8.5 amperes only.

However, the dealer told me it is unlikely for multi-split units to hit the maximum amperage ceiling (i.e. power usage) and asked if I was prepared to authorize him to set the compressor

maximum current load to 11 amperes. Obviously I agreed because that would give me higher cooling capacity when the occasion demands it. I didn't think all 3 fan coils would be switched on at the same time as there are only two persons living in the hdb flat.

You would need to run the electrical wiring for your apartment before the installer comes to fix up the aircon. Without any source of electricity he would be unable to test the aircon for correct and proper operation after the installation.

Finally, you could locate the 15-amp socket for the compressor anywhere, as long as the socket is near the aircon trunking, so that the cable could run and be hidden inside the trunking itself. Thus I have the 15-amp socket located inside the MBR, although the compressor is placed outside the window of the dining room.

Cooling Capacity
OK, once you have decided what brand / type of air-con you want to install, you need to know what (cooling) capacity is required to cool down your space, be it the bedroom, dining, study or living room, etc.

Some dealers have their own formula. Obviously the volume of the space, rather than simply the area and outside ambient temperature, play a part in determining the cooling capacity required, but the following rule of thumb seems to work for me:

Area (Length x Width) X 65 = BTU/hr

E.g. Room size 10ft X 10ft = 100 X 65 = 6,500BTU/hr.

Coming soon..
Understanding the Technical Specs
i.e. How to Read the Starmex Technical Table

Related Posts
1 Choosing an Air Conditioner
2 Energy Saving Tips for Air Conditioners
3 Installation & Placement of Air-con Units
4 Air Conditioner Cooling Algorithm