Do you use Economy mode on your air conditioner?

Most split-system air conditioners have some form of Economy mode, which can be activated via the remote, and which limits or reduces the cooling and heating output a bit in order to reduce power consumption. This mode might be referred to as Economy, Eco, Econo, Active Energy Control or similar names; it might also use a human presence sensor, which detects whether someone is actually in the room, and switches into economy mode if no one is there.

If you’ve got a split-system air conditioner with these power-saving features, do you use them? If so, have you noticed any significant differences in the cooling/heating output, or in your electricity bills? (It can be hard to tell exactly why household power consumption has gone up or down in any given period, so I’m just looking for anecdotal evidence here.)

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No - Economy mode = less heat or cooling!

MHI invertor aircons approx 8 months new.

Isn’t it just an invissible shift in the set point for the operating temperature? That’s what the manual said in the fine print?

We do not use it, as when cooling everything seems hotter or more humid. And I have tried it, hence the observation.

It may make more sense on an older style non invertor type aircon. Although you could simply change fhe set temperature a few degrees up or down too once the room feels about right.

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We have two Mitsubishi Heavy split systems (open plan living area & main bedroom). There is a High/Normal/Eco switch. Eco operates the unit 1.5 degrees higher (in cooling mode) or 2.5 degrees in heating. We don’t use it. Our unit is set at 27 degrees C now and will gradually rise to 30 degrees (max) at the height of summer. We farm & work outdoors most of the time, so it is only to take the edge off when we come in or have visitors. We don’t use it to cool the house, only people, and only in short periods, eg lunch, dusk when insects are a problem.

Compared with the one portable refrig air con we had, the power usage of these is way, way lower. I am too lazy to look it up, but I compared the power usage of our house for a month before (no air-con) and after installation and there was no appreciable increase. Welders, compressors, pumps etc are also in this bill. Eco mode may not have saved anything.

The Dimplex portable cost $0.46/hr to run and meant insufficient power to run other things (the lights would dip, the microwave slow, the compressor wouldn’t charge). It didn’t have an Eco mode, but did have a lower setting apart from temperature. Don’t know what it did as we didn’t use it and the instruction book & brochure don’t go into detail. We are on a SWER line - hence the power problems.

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No. We use the thermostat. Setting the target temperature nearer the ambient will save far more. Instead of 23C all year round we turn it off between seasons, set to 19C in winter and wear a jumper, set to 26C in summer and wear shorts.

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No. We tried, but it just doesn’t work to raise or lower the temperature sufficiently. Perhaps if we left it running all the time, or at least for long durations it may work?

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We have four split level air conditioners in my home, and we have tried the Economy on each of them, but found it was cheaper to place the temperature on 23 degrees and allow the thermostat to control this.

In Economy mode the temperature was either too warm or too cool for us.

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Don’t have aircon…

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So it’s permanently on econo mode??

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Air conditioners are sized for any given location including room volume, climate, building type, etc. Selecting the economy setting effectively forces the unit to act as a much smaller capacity than it was chosen for.

The laws of physics prevail here. If a given amount of heat is required to be transferred, then a proportional amount of energy (electricity) needs to be expended. You get nothing for nothing. Adjusting the thermostat setting further away from your comfort level will achieve exactly the same outcome.

I have two recent model MHI reverse cycle units, a 7.1kW main unit and a 2kW bedroom unit. For those technically interested, I have measured both with accurate power measuring equipment across the entire inverter speed range. In both units the economy setting forces the compressor to run at minimum speed.

Power draw of the 7.1kW unit on cooling measured 2.2kW at maximum compressor speed and just under 600W at minimum or economy setting. The 2kW unit measured 600W at maximum and 180W on minimum or economy setting.

The only time I have used the economy settings on both was during a long power blackout in a hot spell which allowed my small house connected backup generator to keep the units ticking over on minimum for some relief from the heat. Above my comfort level but still much better than nothing. The genny trips out on overload if they are run in their normal operating modes from it.

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Our quite old 8.4 kW Fujitsu inverter split system does not have ECO/ECON mode mode but do have DRY mode (more about the results my tests with that mode later).

So I got a friend with a 7.4kW Panasonic split system to do some tests with it in COOL only and COOL plus ECO mode and with the temp set at 25 deg. when the outside air here in Brisbane was very humid and the temp was around 30 deg. Over a 2 hour period, the ECO mode used 35% less power and he was quite satisfied with the comfort level in terms of temp and humidity. He now always uses the ECO mode.

My experiments with the Fujitsu in DRY mode in similar conditions have produced similar results. So now we usually use DRY not COOL mode when it is hot and humid.

I think the way air cons operate in ECO/ECON and DRY modes may vary greatly between brands/models and that this will influence power consumption and comfort levels. So too will the air temp and humidity level and the length of the test period.

Given how much power is used by air cons and their impact on bills and peak demand, I think getting more info for consumers about power consumption and comfort levels when in ECO/ECON mode (DRY is probably less important to many people) should be a high priority for govts and industry. Eventually, I’d like to see manufacturers being required to provide info about power consumption in the various modes including ECO/ECON from tests conducted in standardized conditions. This is done now for COOL and HEAT modes for the efficiency star rating system.

Meantime, I think it would be beneficial if more people were aware of and tried ECO/ECON mode.

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It might also be useful if the manufacturers provided a digital display of the actual power consumption as part of the device. Given all the smarts in a modern invertor aircon the system knows exactly what mode it is in and the performance demanded of it. Yes it might need another $2 chip to monitor directly power draw from the supply.

The output could be to the head unit LCD or via a IOT data link to your favourite device.

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Good idea, esp since air cons usually use a lot of power, are often used for long periods, and power use can be influenced by temp setting, operating mode, etc.

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There are some new models that can display current power usage on the indoor unit, e.g. LG’s new WH series. Also, wi-fi enabled models usually have a smartphone app that can do likewise, and also log the unit’s power usage so you can monitor your usage more easily.

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If your machine doesn’t have re-heat then what does ‘dry’ actually do that normal cooling doesn’t do?

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Our aircon service expert recommended that we run our Fujitsu split systems on Dry for 20 minutes or so after operating them in Cool mode so as to dry the moisture off the evaporator coils and their fins so as to reduce the build-up of mould.

These systems build up mould in tropical environments like Cairns which eventually causes the tiny drains in the indoor units to block up, and results in water flowing down the inside walls where they are mounted. The mould would also have health risks associated with it.

We have him professionally service our split systems each year which takes around 2 hours per system, and the interior of the indoor units looks absolutely disgusting before he starts, and sparkling clean when he finishes.

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Thanks Chris. Good to know this exists.

Maybe some community members with such machines, and Choice when testing them, can use these functions to compare power use for cooling and heating (at the room and outside air temps) in cool and heating modes with and without eco/econ mode activated?

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see my post below in reply.

In my experiments, covering up to 2 hours use, in hot humid conditions DRY mode used 36% less less power than COOL mode!

The Fujitsu 2003 manual says this about DRY mode :

Use for gently cooling while dehumidifying your room.
You can not heat the room during Dry mode.
During Dry mode, the unit will operate at low speed: in order to adjust room humidity, the indoor unit’s fan may stop from time to time. Also, the fan may operate at very low speed when detecting room humidity.
The fan speed cannot be changed manually when Dry mode has been selected.
An important feature of DRY mode on this machine is that the required temperature setting can be changed. I think that with some machines t the temperature can not be set when in DRY mode. Others may be able to comment on this.

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Yes, this can happen and not only to the drain holes but also to drainage pipes in which water can collect. I have managed to solve both problems by pushing flexible metal curtain hanging cord up the drainage pipe.

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The thicker whipper snipper cord also works well in helping to clear the drains.

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