Frequently Asked Questions
Here are some questions people often ask about their air
conditioners. If your questions are not answered here, fell free to give us a
call and we’re always more than happy to provide all the advice you need.
What size unit should I purchase?
The amount of wattage you will need depends on the size of
the room(s) you want to heat/cool and the heat load which is determined by
environmental factors such as the amount of windows and sunlight in the room,
weather conditions and what type of insulation you have. Generally, the bigger
the area you have, the more power you will need to service it. Optimum Air is
more than happy to give you all the advice you need in this regard.
What is an inverter system?
An inverter system lets your air conditioner alter the
speed of its motors (compressors) in response to cooling demand. The result is a
controllable and energy efficient system that is not only cheaper to run, but
also uses a smaller power supply.
See our web page on
What is the difference between a split system and a room air conditioner?
A split system has an indoor and outdoor unit that is
connected together. They provide quieter and more efficient air conditioning
than a single room air conditioner. They work by having the condenser (the noisy
bit) in the outside unit and then having one or more indoor units
that contain the fans.
A package unit (room air conditioner) requires no external
components and has to be installed through a window or hole in a wall. These units are
good for small rooms, but some people find them bulky and unattractive. They
are also much noisier than a split system because the condenser is located
immediately behind the outlet, whereas a split system's condenser can be located away
from the rooms being cooled.
Make sure you check out our web pages on
Multi-Splits, and Ducted Systems.
What is the difference between a split system and a multi
A split system has an indoor and outdoor part that is
connected together. Meanwhile a multi split system has just the one outdoor part
that is connected throughout the house through multiple indoor parts installed
in each room. So while a split system powers up the one room, a multi split
system powers up multiple rooms from one outdoor unit.
What is the difference between a split system and a ducted system?
Nowadays, almost all air conditioners are split
systems. In fact virtually all ducted systems are a kind of split
The term "split system" refers to a type of air conditioner
where the compressor is connected to an indoor unit via pipes. The
actual type of air conditioner can be either a wall-hung system or ducted
system. The ducted system transfers its conditioned air through
ductwork. The wall-hung system has an indoor unit connected directly
to the outdoor unit with pipes, and conditioned air comes directly out of
the indoor unit without the need for any ducting. Of course, this
means the wall-hung indoor unit can only condition one room or area.
To condition more than one area a wall-hung unit would need to have multiple
indoor units. To condition multiple areas with a ducted system you
still need only one indoor unit - the conditioned air from it is transported
using the ducting.
Some people refer to "split systems" when they really
mean "wall-hung split systems". It is just a shortening of the term.
A "split system ducted" air conditioner is, likewise, usually referred to as
simply a "ducted air conditioner".
Again, see our web pages on
Wall Splits, Multi-Splits, and
Is a cooling-only system better than a heating/cooling
Cooling-only systems are not necessarily better than
combined cooling/heating systems, but they are generally cheaper to buy. Air
conditioners that can both heat and cool are known as reverse-cycle
systems. This is because the normal cycle is to pump heat from indoors to
the outside. By reversing this cycle, the heat can be pumped from outside
to inside, and thus the unit becomes a heater. This can save you money
because just the one appliance performs both heating and cooling, obviating
the need to buy a separate heater.
How often do I have to clean my filters?
Return air filters require regular cleaning. The
frequency depends on how dusty the house is. If not cleaned the unit can
ice up and stop working. The condenser (outdoor unit) also needs to be dust
free with an unobstructed air flow. If you do this three or four times a
year, that's almost always sufficient. Optimum Air can design a maintenance
programme for you to make sure that filter cleaning (along with regular
checkups) are done and give you complete peace of mind.
See our separate web page in the Service section on
Cleaning your Filter
Should a thermostat be set to "auto" or "cool" /
Today, most air conditioners have an "auto" setting on the
thermostat that makes the fan operate only when the temperature requires it.
This is generally the most used and efficient setting because programmable
thermostats maintain a steady temperature and reduce energy use by only working
Using "auto" means the air conditioner itself is allowed to
decide whether to heat or cool. For instance if it’s 30° outside, you’ll
probably want the machine to cool, and the "auto" setting will do this. If it’s
10° outside, naturally the desired operation is heating.
If the indoor and outdoor temperatures are roughly the
same, however, this can sometimes confuse the "auto" setting. In this case you
might like to over-ride the auto setting by specifically letting the machine
know that you want it to cool or heat (or possibly just de-humidify) by using
the relevant setting.
Can I leave doors and windows open while operating the
You can leave windows and doors open, but it’s not a good
idea if you’re trying to heat or cool the room. For tips on saving money on
running your air conditioner, please see our separate web page of
It says on the air conditioner that it uses 6,000 watts of
current (thus requiring a 25 amp circuit), yet the manual says the machine only
has a rating of only 2,500 watts. What is going on here?
Electrical input wattage and refrigeration wattage are two
different things. The important thing to note is the refrigeration rating,
which is how effective the machine is in pumping heat. In fact machines of the
same cooling/heating rating might use more or less electricity to achieve this.
The less input energy used to achieve the same refrigeration rating, the
better. This is how the Energy Star ratings are calculated. This gives the
efficiency of a machine in a way most people can understand: the more stars, the
"R22", "R410a", "R407c" and "R417a" mean?
These labels refers to the type of refrigerant gas the air
conditioner uses. Older hydrochlorofluorocarbon (HCFC) based refrigerants are
in the process of being phased out due to their ozone depleting potential. That
means the current air conditioning refrigerant R22 has a phased reduction until
The main replacement that is being introduced is
hydrofluorocarbon (HFC) R410a which has an ODP of zero. Unfortunately it has a
higher direct greenhouse warming potential than R22 but indirectly it's less
damaging to the ozone layer. R22 manufacturing by-products caused a far higher
total greenhouse warming potential.
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. This 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
If you have an old air conditioner or refrigerator it is
important to dispose of it properly. If the refrigerant is released into the
atmosphere the damage to the ozone layer and greenhouse warming potential is
roughly equivalent to operating a medium-sized four cylinder car continuously
for six months! The refrigerant gas can be reclaimed (pumped out) and disposed
of in a safe way by a licensed refrigerant handler, such as Optimum Air
I hear that you can catch Legionnaire’s
Disease from air
conditioning. Should I worry?
Legionnaire’s Disease has been overblown by the media.
CANNOT catch Legionnaire’s Disease from a domestic air conditioner. This
disease is formed in cooling towers which are only used in very large commercial
operations such as in office blocks and shopping centres.
Cooling towers can provide an ideal place for legionella
bacteria to grow (temperatures between 28° to 40°C) and the operation of the
towers causes drift which aerosols the bacteria allowing people to breathe it
in. There is, however, probably more danger in handling potting mix than from a
cooling tower because by law, all towers have to be regularly maintained and
treated with biocide.
Should outdoor units be covered in winter?
Outdoor units are designed to withstand seasonal changes so
do not need to be covered. The heat pumps inside the unit operate year round
and if you cover them, it may cause damage.
If an outdoor unit needs replacing, should the indoor unit
be replaced too?
Generally it is a good idea to replace the entire system
when a major component of the system fails to operate correctly and cannot be
repaired. That's because air conditioning and heating units are designed to
operate as a complete, matched system. In fact it can sometimes be downright
impossible to obtain an indoor or outdoor unit to match its counterpart if the
unit is more than a few years old.
Can plants or shrubs be planted around an outdoor unit?
Yes. However, make sure there is plenty of room around the
outdoor unit so air can freely flow in and out of it. Without room for air
circulation, the unit can overheat and damage itself. It's also a good idea to
trim shrubbery and limbs back because they can cause damage if leaves or twigs
are sucked into the outdoor unit.
What is the average life expectancy
of an air conditioner?
The typical life expectancy of an air conditioner is about
10-15 years. When the air conditioner starts having problems that are not
cost-effective to fix, it may well be time to replace it. Be wary of
spending more than 50% of the replacement value of a machine on repairs.
If the machine should need a similar repair within a few years, you may as
well have bought a new one at the time of the first problem. Modern machines are
usually far more efficient than old systems. This is an added bonus of
replacement: the machine you replace it with will almost certainly use less
electricity than the old one.
I am trying to cut and paste text from this website into my word processor and
it appears invisible! What do I need to do?
The text on this website is white. If you paste it into a word processor
with a white background, the text will be there, but since it's white on white
you won't be able to see it. Either highlight the pasted text and turn the
text colour to black, or alternatively, when you paste the text don't use a
normal paste operation. Choose "Paste Special", and then paste the text as
"unformatted text" (or "normal paragraphs") into your word processor.
Footnote: the above is no longer true, we've changed all the colours on
the website and the text is now black! The above point does apply to some
other websites, however.
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