Here is a wonderful titbit of information that will make you the hit at the annual dinner of the Denpasar Toastmakers Club.

Did you know there is no such thing as “cold.” Cold is in fact a worldwide con created by exuberant salesmen who want to sell fridges to Eskimos.

You see “cold” doesn’t exist, cold is in fact an “absence of heat”.

To make heat you burn electricity, gas, coal, sweaty socks or any other energy to turn it into heat energy. In an electric fire or toaster all those little electrons dash round and get so excited that they generate lots of heat. 1 kilowatt of electricity will produce 1 kilowatt of heat (well nearly). BUT if they run around backwards they won’t produce cold. You can’t create cold. To make something cold we have to remove heat so we use a different process. In my recent article on Nasty Gas (see the Bali Advertiser or Mr Fixit websites) you will find the cooling cycle used in refrigerators and air conditioners.

One of the great things about Bali is the weather, we enjoy a tropical climate but the sea breezes make it very liveable and keep the mozzies away. Many of us get used to the temperature and sleep with a ventilated room (good for the environment) but for many people an air conditioner is a must particularly when it gets up to treacle toffee on the stickiness scale.

Air conditioning is a big subject but I will try and keep it simple. Firstly we need to understand a few things.

“How big is your peka?”
“I beg your pardon!”

In Indonesia the power of air conditioners is usually stated in pekas (what!). A peka in fact comes from the Dutch PK which is short for Paarden Kracht which translated means horse power (HP) - but not quite. A PK is in fact a metric horse power which is slightly smaller than a real horse power, this is probably because the Dutch had smaller metric horses. One horse power is the equivalent of 746 watts while a PK is 736 watts or 0.736 kilowatts.

The amount of cooling an air conditioner achieves is measured in BTUs (an archaic imperial measure known as a British Thermal Unit). To impress the Toastmakers you might like to tell them that a BTU is the amount of heat required to heat one pound of water through one degree Fahrenheit.

During the height of the British Empire a fiendish plot was hatched whereby British Thermal Units were spread liberally all over the world to confuse scientists and engineers and give Britain a technological advantage. The plot was finally exposed and Europeans converted all their BTUs into Kilowatts at an exchange rate of 1 Kilowatt for 3,413 BTUs.

How much cooling can be achieved by an air conditioner is determined by it’s power and it’s efficiency. This is measured as COP (Coefficient of Performance) which is the ratio of electricity input to cooling output. Back in the days of window mounted box air conditioners you could expect a COP of around 1.5 ( 1 kilowatt of electricity achieved 1.5 kilowatts of cooling). Nowadays with modern split air conditioners you can expect a COP of up to 4.5 (1 kilowatt of electricity will produce 4.5 kilowatts of cooling).

“Just a minute! How can 1 kilowatt of electricity produce 4.5 kilowatts of cooling?“

You must remember that an air conditioner is not converting energy like an electric fire converts electrical energy into heat energy, we are simply moving heat energy from inside your house to outside.

A modern air conditioner is in fact a heat pump, it pumps heat. It is also interesting that many air conditioners are “Reverse Cycle” they can (unlike the electric fire) run backwards pumping heat from outside your house to inside your house. A modern heat pump is four times as efficient at heating your house than an electric fire.

So you want to buy an air conditioner? Firstly you need to determine how much heat you need to remove from your room(s). A detailed calculation is needed including the floor area, the insulation of the walls and ceiling, the height of the room, the number of windows and doors, how much sun comes into the room, how many people are in the room (and how hot they are!) and the electrical appliances in the room that produce heat including light bulbs. From this the size in pekas can be determined.

This is complex but as an extremely rough guide the following table may (or may not) help:

This is based on a split air conditioner with a COP of 4.

What make should you buy? Well basically you get what you pay for. Generally regarded as the better air conditioners are Daikin and Mitsubishi. At the other end of the scale names like “Chou Well Hung”, “Poo” and “Dung” speak for themselves.

There are many to choose from. Toshiba tend to be a little more expensive than the others, particularly on spare parts, while brands such as Panasonic, LG, Sanyo, Samsung, etc compete at equal levels and try to outdo each other with extra features such as self cleaning, ionisation, bacteria filters, tea makers and toenail clippers. A rugged and reliable choice is Mitsubishi Heavy Industries (not the same as Mitsubishi Electric).

As a final comment, the efficiency of your air conditioners will drop quite markedly as the filters get dirty. It is a good idea to get them cleaned and serviced regularly, perhaps every three months if you use them a lot.

If you don’t understand a word of all this don’t worry about it, just have another glass of wine and put your feet up with a good book.

Phil Wilson

Copyright © Phil Wilson 2009
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