CHOICE membership

Air conditioner review - your feedback needed!


#1

As summer is fast approaching we are reviewing our online content for air conditioners. To make sure our information is spot on, we’d love to hear your answers to the below.

  • What air conditioning system do you have (i.e. reverse cycle, ducted etc)?
  • What features were important to you when choosing which air conditioner to buy?
  • Are you concerned about the cost of running your air conditioner and if so, what do you do to keep costs down?
  • Finally… feel free to comment or ask anything else about air conditioners!

#3

Type: Fully ducted (insulated), reverse cycle, Panasonic 11 Kw (with room and zone control)

Important Features: Big enough unit to cool or heat at least 3 rooms at a time when it is needed. Easy to understand and use controls

The cost at least doubles our elec bill when we run it so we try opening/closing windows, using our ceiling fans, before we run the unit. You really need to ensure the roof and if possible the walls are properly insulated and have proper curtains and or window film to reduce heat loss/gain if you are going to use any air con in your home. We are going to fit “Whirly Bird” roof vents this year to reduce the heat load held in the roof cavity in Spring/Summer and have them fitted with vent blockers to retain the heat in winter as we find with the lower ceilings that a lot of heat in summer is affecting the time it takes to get the cooling to the desired level.


#4

I have four individual wall split system two large units 7.1 kw for living areas and two 2.0 kw units for the bedrooms that are used. Most units you can buy are very efficient these days often more expensive units are not more efficient than a cheaper unit. I love the fact they can be used to cool a area of your house very quickly as the fan speed can be set very high to remove the heat from the room. I also close off doors and rooms that are not been used to only cool or heat the rooms I’m in. To keep running costs down I close of the house to the outside world and start the large aircons early to stop the house warming up by setting the units at 23-24 degrees early in the day and I never drop past 22 degrees. A lot of people do not realise the air cons do not add cool they remove heat from the room in the evaporator / indoor unit of the unit which absorbs the heat. Keeping your house cool and not letting it get to warm will save you receiving huge power bills. It never ceases to amaze me how many people leave the house all day come home to a stinking hot home and then turn on the air con and because the house doesn’t cool down quick enough they keep dropping the temp lower and lower making unit work ever harder even though that’s the wrong way to cool your home when it’s hot, you need to flush out the warm air if you can first. Most units have timers which can be set or if you have wifi there are remotes that can operated from a app on a smartphone from anywhere which are great so you turn you unit on when you know it’s going to be very hot at work or from anywhere really. Also for most applications the temperature should only ever be between 20-24 wether your heating or cooling not 16-18 to cool or 26-28 to heat that’s when they use suck up power.


#5

It is implied this is about refrigerated A/C. Is that the intent or are you also asking about evaporative systems ?


#6

Hello TheBBG,

Asking about any A/C system, evaporated included. CHOICE doesn’t currently provide reviews on evaporated systems however we’d still be interested in knowing if you have one and what features were important when choosing one.

Cheers

Antonia


#7

Hello Grahroll,

Thank you for taking the time to reply.

Just a quick question to clarify, when choosing your ducted system did you consider any specific features such as ‘sleep mode’ or ‘human presence sensor’?

Thank you again.

Antonia


#8

Hello Paul,

Thank you for your detailed reply.

Just a quick question to clarify, when choosing your split system, did you consider any specific features such as ‘sleep mode’ or ‘human presence sensor’?

Thank you

Antonia


#9

We have the whole house on ducted reverse-cycle. The house is heavily insulated in both walls and ceiling and is double glazed. It is oriented to the sun and has verandas on the north. We have fast growing shrubs on the north too that are cut in May and grow up in September. We have shutters on East facing windows to keep the sun out in summer and let it in during winter. The aircon has individual zone control so we leave off rooms that are unused and keep those door shut. We selected an efficient model at the time it was installed.
We DO NOT keep the temperature at 23C all year round! In between seasons we don’t run it at all. In summer we turn it off and open the house at night once the outside temp drops to about 24C and allow the the house to cool down. It is closed up again at sunrise. When cooling the thermostat is set to 26C and we wear shorts, T-shirts etc. In winter it is set to 19C and we wear trousers, jumpers and ug boots.
We still find that it is expensive to run when it is very hot or cold. Our climate is quite harsh, it hits 43C in summer and -4C on winter nights. Under those circumstances you cannot rely on passive measures unless you live in a deep hole.
I know people who have badly designed and badly insulated houses who run the air at 23C all year round - their bills are toe-curling. They whinge a great deal. You can’t tell them anything.


#10

Our house in suburban Melbourne was built with ducted evaporative and it works well. The area is generally low humidity in summer. With refrigerated the house needs to be sealed and the air is recirculated but with evaporative there is fresh air being circulated through, windows open, light coming in.

The biggest down side of evaporative is it gets ineffective with even moderate humidity. If we have a single 40+ day we usually stay comfortable <25, but successive 40+ days are usually accompanied by increased humidity and interior temperatures have risen to the low 30s. My system starts getting palliative rather than comforting above 35% RH, so on hot days with 50% humidity it is not much better than just the fan without the evaporative system going.

Things to consider with evaporative: Wool fibre or celdek pads - there are proponents of each. Celdek pads seems more efficient and longer lasting but cost more. Most newer systems come with Celdek pads. Pads need replacement at intervals of 5-15 years depending on care and amount of use. Good practice is to rotate the pads (eg around N-S-E-W) one year, and reverse each pad in its bracket the next, so over time each pad has been exposed to the same weather direction and each side of each pad has been exposed to the elements for the same amount of time. That maximises pad life.

Many modern evaporative systems have internal spring and motor driven winter shutters; low end and older ones require manual capping during winter months to avoid warm air rising through the ductwork, or capping the duct vents. I found capping at the ductwork is more effective since caps at the unit can be quite leaky. There are commercial ductwork caps available, but I just cut some foam and put it in the ductwork boxes and that has been very effective.

Routine maintenance includes running a weak bleach mixture at the start of season to kill mould or mildews that cause legionnaires disease. That is not the problem it is with large scale commercial sized towers, but remains best practice. An evaporative system should have an automatic water dump to periodically empty the water so it does not have a chance to build up nasties; the alternative is a water bleed that continuously empties an overflow amount while the pump is running. The dump results in renewing the water periodically and when turned off, the bleed dilutes old with new.

Applying the winter cap, shutting the water, etc, spring cleaning, pad rotation, and recommissioning/checkout is stone simple but requires a climb up the roof. Multi-story buildings and steep roofs do not make it fun and on wet roofs it can be dangerous / slippery.

Prior to selecting an evaporative unit read the service recommendations, note how much of the routine operating requirements are automatic and how many require a trip up the roof. Some newer systems are automated enough that it is reasonable to skip preventative maintenance (excepting things required for warranties) and just fix anything that breaks when it breaks.

My roof is not steep and not onerous to climb so my system has had annual maintenance; a neighbour’s house was completed in 2003 and he cannot find anyone keen to go up his 2nd floor steep roof; he has never had any maintenance but still has not had a worry to date.

Today I would buy refrigerated although it costs about 5-10 times more to operate; it reduces inside humidity and is effective regardless of the outside temperature and humidity, and there is no roof climbing required. However as electricity prices continue to rise and government seems disinclined to commit to a long term energy policy or re-regulation, running costs could be the decider for many in low humidity regions where evaporative is a valid choice.


#11

Type: reverse cycle
Features: energy efficiency, timer, cost of unit, brand reputation
Cost concerns: Not particularly, as I am not a “heavy user” - they really are only for those “extremes” of heat and cold (predominantly cold) that crop up. I use ceiling fans for the most part in summer, and also use them on reverse with the air con to better distribute the hot air in winter.

I’ve been generally disappointed with the performance of the Fujitsu units I purchased. Although the rooms are bigger than average, they are not enormous and are well-enclosed. Even so the units don’t seem to be able to recognise the temperature (for example, I will generally set the temp to 19 degrees in winter, which is enough to take the chill off - but I find I have to crank the setting up to about 24 degrees to achieve any noticeable heating effect, and as a result, the unit runs constantly). So it would be useful to test the accuracy of the heating and cooling sensors. A second-hand Kelvinator I installed in a less-used room is infinitely better despite that room not being fully enclosed.


#12

Hello Farmer Raq,

Thank you for taking the time to reply and share your suggestion to test the accuracy of heating and cooling sensors.

Quick question, you mentioned energy efficiency as a feature, by this do you mean star ratings or a specific feature such as sleep mode or human presence sensors.

Thank you again.

Antonia


#13

Hi Antonia,

I was thinking more along the lines of star ratings. Human presence sensor was not of interest to me as I only use the air con when I am planning to be in the room for any length of time. Sleep mode was a consideration, but more for convenience rather than as a specific energy saving measure.

Hope that helps.


#14

Hello FarmerRaq,

That helps a lot.

Thank you

Antonia


#15

Hello TheBBG,

What a great comprehensive answer; this supports similar problems I’ve heard with evaporative systems in Melbourne.

Thank you

Antonia


#16

Hi Paul

We use 24 as our cooling setting and 18 as our heating. If we are going to use our AC on any given hot day we start it like you in the early morning and leave it on all day or if it is going to a “bad” week we start it and leave it on for the week with the timer controlling a small break each night, however it uses lots of power so as I put in my response we try to use all other means to keep the house cool during summer and warm in winter before we consider the AC and in winter we mostly heat at night so we start the AC in the afternoon when the house already has some heat load. Requires watching weather reports so we anticipate the “bad” days and weeks, when we need to run the AC.

Hi @airwin

No as we only use it when we actually want it on, those considerations were not important. It does come with a sleep mode but it is never active and our zone control is another controller and not part of the AC controller. The timer function is definitely used and our’s gives us quite good setting control.


#17

Another issue in highly mineralised water areas is the build up of salts on the pads and interior and this may require more frequent cleaning of the whole machine interior and the pads to get the best life and efficiency out of them. We had several evaporative systems when we lived in the NT and Mt Isa and all were mounted on pads on the outside of the house, mostly out of the sunny spots.


#18

Hello Grahroll,

Thank you again. I’ve included your answer in an internal document regarding evaporative systems.

Kind regards

Antonia


#19

No I did not as these are gimmicky features that don’t add much value at all. I would prefer to buy a good quality brand that will last 10 plus years.


#20

Hi Antonia

We bought a house in lovely warm Queensland (the state of confusion) that was very poorly insulated, and it is impossible to post fit it as there is no roof cavity, and we can’t get into the walls. The situation is exacerbated by the fact that we get sun on the house all day, plus it is exposed to the prevailing winds. There were existing old and inefficient ceiling fans, that we had to replace.

In the colder months the house is like a morgue, and in the warmer weather it is like a sauna. Consequently, we needed both heating and cooling, but cooling more often than heating,

We post fitted reverse cycle split system units for the bedrooms and the main living areas.

The main criteria was that 1. the units had to be able to handle a larger area than they were put in. This was to ensure that they could effectively cope with the heating/cooling load. Once we knew the size of the units, we then selected 2. the most efficient. Finally, we wanted 3. units that would last, and not rust in the harsh salty/sunny/windy environment we live in.

We only use the air cons when we must. Last summer we only used them for just over a week when the external temps were over 40C. This winter, we only used them for short periods to take the chill off the air. There was a spike in our electricity bill, which was from the ceiling fans and the air cons.


#21

Our cousin is a Refrigeration Mechanic and advised us on the heat loads, air movement needed, type of ducting etc we needed to use for our house. Getting an inspection and the advice of a good AC mechanic is very worthwhile in planning your needs. Some units are too big in some installs for the job they need to do and yet others too small. Refrig Mechs have heat load calculators, and instruments to ensure a good outcome but you do have to find the good ones.