FREQUENTLY ASKED QUESTIONS

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Frequently Asked Questions

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AIR CONDITIONING QUESTIONS

How do I size an Air Conditioner?

The output capacity is a measure of the amount of heat that will be removed (cooling) or added (heating) to the room/s in your house by the air conditioner. The output range you need will depend upon your particular requirements. Air conditioner outputs are measured in kilowatts (kW). As an approximate guide for sizing a room unit allow:

125watts (0.125kW) per square meter of floor area to be cooled in living areas;

80 watts (0.080kW) per square meter of floor area in bedrooms.

These estimates depend on the climate and the efficiency of your house design (orientation, glazing and insulation levels).

It is advisable to get a full heating or cooling load calculation from an authorized air conditioning installer or manufacturer before you buy.

What is an Inverter?

A new innovation in air conditioner technology is the use of an inverter or variable speed drive in the motor system that drives the compressor. While these systems tend to look less efficient at full load (i.e. their star rating at rated capacity is not always as high as conventional air conditioners), they tend to be very efficient at part load operation, which is a more common mode in a typical household.

So if you are likely to use an air conditioner for long periods because you live in a hot climate, it may be worth considering an inverter system. They are, however, more expensive to buy, as a rule, but cheaper to use.

Air Conditioning Tips

Thermostats should be set between 25–27°C. Every 1°C lower can increase running costs by up to 15% or cost you for repairs because they do like a break every so often.

If there is a hot day forecast, then pre-cool your house the night before. This is especially effective if your house has a high thermal mass such as solid brick. This will allow your air conditioner to work at its optimum during the cool evening, saving power and wear and tear on the unit. It also allows the unit to keep on top of the heat load as it begins to warm up during the heat of the day.

Power kilowatts and Refrigeration kilowatts
Electrical input wattage or Hp, and refrigeration wattage are two different things.

A unit drawing 746W (1Hp) of electricity may move 2 to 3.5 times that in cooling or heating wattage. Only the latter refrigeration kilowatt (kW) rating will give an accurate representation of unit size.

Input Power Conversions.

To convert from Hp to kW multiply by 0.746

To convert from kW to Hp multiply by 1.34

To work out how much your unit will cost to run multiply the kW input figure (electrical) by how much you pay per kilowatt hour for your electricity.

i.e. 13.4c/Kwh x 1.28kw = 17.1 cents per hour to run.

Tell me about Refrigerant types R22, R410a, R407c, R417a

Older hydro chlorofluorocarbon (HCFC) based refrigerants are in the process of being phased out due to their ozone depleting potential (ODP). That means the current air conditioning refrigerant R22 has a phased reduction until 2015. Import levels at 2009 equate to ~1800 metric tonnes dropping to 1350 in 2010, 720 in 2012 and 180 tonnes in 2014. From 2015 to 2030 approximately 45 metric tonnes will be available per year to service existing equipment and none by 2030. Alternative refrigerants (drop ins) will most likely be available for older equipment so you will still be able to repair them using these.

The main replacement that is being introduced is hydro fluorocarbon (HFC) R410a which has an ODP of zero. Unfortunately it has a higher direct greenhouse warming potential (GWP) than R22 but indirectly it’s less damaging. R22 manufacturing by-products caused a far higher total GWP.
R407c is another of the R22 replacements that requires polyol ester oil.

R417a is a drop in replacement for R22 systems that requires no changes and uses the existing mineral oil. Will become the simplest replacement as R22 is phased out.

If you are considering purchasing a new air conditioner, it’s worth shopping for an R410a or R407c unit. They’re marginally more efficient, better for the environment and will be more future proof in terms of servicing Another benefit is reduced unit size relative to an R22 unit. Systems using R410A refrigerant run at a pressure of approximately 1.6 times that of similar systems using R22 so it can’t be used in existing systems due to different components such as compressors and the pipe wall thickness needing to be higher on R410a.

What is the best brand?

The old adage ‘You get what you pay for’ exists for a reason. The dearer units such Daikin are generally (not always) more efficient and or quieter. They also go together better and give you a better finished product. This translates to easier servicing should the need arise which in my opinion makes the additional purchase costs worth considering.

However, some of the cheaper brands provide excellent value for money and offer very good performance. Final decisions should be based on specific unit performance and value for money. There is very little difference between the mainstream and top units sold these days. It's only in the very cheap units that quality begins to suffer.

Understanding Inverter Air Conditioning Units

When a mechanical device starts, there is often a surge or spike in the power consumption to start up the machine. This power spike results in a high running cost as the device has to drain so much electricity to get started. You can often see this in your home when the lights flicker or dim for a few seconds when the air conditioner starts up. Because of this, standard appliances such as reverse cycle ducted air conditioners can be quite costly to run.

An inverter however acts like a throttle of a car. Instead of the initial power usage spike, an inverter slowly ramps up. Often when an inverter air conditioning system starts you do not even notice it has started. The unit gets up to speed more consistently and avoids any power spikes which makes the system cheaper to run.

So how cheaper is an inverter air conditioning system to run? It is hard to say precisely but reports show that you can save up to 40% in running costs when using an inverter over a standard non inverter unit. The inverter unit is also better for the environment because it uses less power so it is a more popular and environmentally friendlier option for air conditioning your home.

Inverter systems are usually also somewhat quieter than standard systems and have a more precise temperature control with less fluctuations.
Non-inverter units will eventually be phased out as part of the battle against global warming. Don’t spend money on a unit that will be considered out of touch and out of date very soon and will cost you a fortune to run.

Sure, you have to pay a little more for an inverter air conditioner but it is worth it. The savings on electricity bills alone are worth the extra money but also the more impressive ability to deliver more consistent temperatures. The inverter air conditioner type is consistent through out most brands these days which means most top manufacturers of inverters have a pretty level playing field when it comes to energy efficiency.