Inverter Air Con: Beware Of High Standby Power

[DaveLee1688 1]

In any case, I do find the standby wattage a little high, wonder if we could verify this with the Mitsubishi Electric Japan. Wonder if the numbers were lost in translations. ha

Michael

Those standby power numbers were excerpt from confirmations right from the horse's mouth, via their Singapore office, copied to NEA.

On the pre-heating - at no point during the exchanges with the brand M people did condensation came up as a reason. The only reason quoted was the pre-heating is needed for keeping some oil properly separated from coolant, something like this. So it is speculation.

On the R22 / R410 tingy- I fully support R410 but I am sure brand M is not the only with using R410. The only reason brand D is not using is because Singapore's law does not mandate it until recently, and probably consumer do not want to pay more. At no point did brand M Japan people quote the type of coolant is the reason too. So it is speculation.

I have tried to be very objective in my investigation by first getting NEA to confirm my findings that the condensers are really the culprits. Then, I wrote to brand M people, kind of insisted that they take up the issue with their Japan designers. The findings are their answers to observations I had and they do indeed explain the phenomenon. I did told them that I may share some findings with Singaporeans for the sake of getting to be more energy conscious.

Therefore, whether the additional $10-25 per condenser per month means anything to you, matters to you is entirely your call. What I am saying is that all manufacturers should be honest about their green statement, and be true to it, and not just merely appear to be legit quoting some regulations that have not caught up with time.

Edited September 12, 2010 by mit3a28

[MichaelAng 1]

I entirely agree with you. Hopefully we can get the relevant people to put the records right. I guess it's a matter of personal priority.

Would be interesting to know how the other brands do this if not by heater.

Those standby power numbers were excerpt from confirmations right from the horse's mouth, via their Singapore office, copied to NEA.

On the pre-heating - at no point during the exchanges with the brand M people did condensation came up as a reason. The only reason quoted was the pre-heating is needed for keeping some oil properly separated from coolant, something like this. So it is speculation.

On the R22 / R410 tingy- I fully support R410 but I am sure brand M is not the only with using R410. The only reason brand D is not using is because Singapore's law does not mandate it until recently, and probably consumer do not want to pay more. At no point did brand M Japan people quote the type of coolant is the reason too. So it is speculation.

I have tried to be very objective in my investigation by first getting NEA to confirm my findings that the condensers are really the culprits. Then, I wrote to brand M people, kind of insisted that they take up the issue with their Japan designers. The findings are their answers to observations I had and they do indeed explain the phenomenon. I did told them that I may share some findings with Singaporeans for the sake of getting to be more energy conscious.

Therefore, whether the additional $10-25 per condenser per month means anything to you, matters to you is entirely your call. What I am saying is that all manufacturers should be honest about their green statement, and be true to it, and not just merely appear to be legit quoting some regulations that have not caught up with time.

[MichaelAng 1]

aircon spoil is replaced aircon, nothing to do with piping if they are installed well in the first place. they are independent cases.

Oh I see. That's interesting. I didn't know that one does not need to change piping when change zircon. So it is a permanent fixings? That means the quality of this installation is very important.

Also mean that someone I enquire few months back tried to con me by saying I need to replace my entire piping so as to fit into the new aircon.

[neubie 2]

Oh I see. That's interesting. I didn't know that one does not need to change piping when change zircon. So it is a permanent fixings? That means the quality of this installation is very important.

Also mean that someone I enquire few months back tried to con me by saying I need to replace my entire piping so as to fit into the new aircon.

if the pipings are done properly first time, dun need changing at all...if the aircons need replacement, just change the condenser + FCU, no need rerun all the piping, just ensure the installers perform pressure testing on the pipings after installation, before handing over to u...

fyi, my non-inverter R22 MHI aircon piping is reused for my toshiba inverter and runs fine, even though installers recommending using the thicker piping (higher gas pressure for inverters). so can save on the copper piping.

haaaa, i'm digressing too much.... back to topic

Edited September 12, 2010 by neubie

[wolflet 1]

I did some digging into this heater issue after the discussion and found this post

http://forums.energymatters.com.au/energy-...y/topic594.html

The author is using a daikin aircon and states that it also contains a heater that draws 50W at standby.

He contacted the manufacturers and was told this

"After speaking to the manufacturers, I have discovered the reason is that they have to maintain a minimum temperature of the refrigerant at all times. If the fluid becomes too cool, it increases in viscosity and can damage or severely reduce the life expectancy of the compressor if it is started in that "cold fluid" situation. As a result, in order to be ready to be "instantly activated" the units have a small heater that constantly maintains the fluid temperature.

The advice from the manufacturer is that it takes at least 6 hours for the unit to warm the fluid sufficiently to allow a safe start, possibly slightly less on a hot summer day and probably more (ideally 12+ hours) in winter when the unit is very cold. However, to save this constant 50W draw, the air conditioners can be switched off at the switchboard AS LONG AS THEY ARE ALLOWED TO WARM UP FOR AT LEAST 6 HOURS OR PREFERABLY OVERNIGHT BEFORE THEY ARE ACTIVATED."

So maybe we can also consider turning on the power to the aircon 6 hours before starting to prevent damage to the compressor?

But this may only apply to certain models of daikin and probably not applicable to those being sold in singapore

Edited September 12, 2010 by wolflet

[neubie 2]

I did some digging into this heater issue after the discussion and found this post

http://forums.energymatters.com.au/energy-...y/topic594.html

The author is using a daikin aircon and states that it also contains a heater that draws 50W at standby.

He contacted the manufacturers and was told this

"After speaking to the manufacturers, I have discovered the reason is that they have to maintain a minimum temperature of the refrigerant at all times. If the fluid becomes too cool, it increases in viscosity and can damage or severely reduce the life expectancy of the compressor if it is started in that "cold fluid" situation. As a result, in order to be ready to be "instantly activated" the units have a small heater that constantly maintains the fluid temperature.

The advice from the manufacturer is that it takes at least 6 hours for the unit to warm the fluid sufficiently to allow a safe start, possibly slightly less on a hot summer day and probably more (ideally 12+ hours) in winter when the unit is very cold. However, to save this constant 50W draw, the air conditioners can be switched off at the switchboard AS LONG AS THEY ARE ALLOWED TO WARM UP FOR AT LEAST 6 HOURS OR PREFERABLY OVERNIGHT BEFORE THEY ARE ACTIVATED."

So maybe we can also consider turning on the power to the aircon 6 hours before starting to prevent damage to the compressor?

But this may only apply to certain models of daikin and probably not applicable to those being sold in singapore

seems logical, as i have heard many pple saying it's not good to unplug the power supply to the condenser unit as it will shorten the life of the compressor for the reasons stated above...

maybe i will install one 24-hour timer to cut the supply of the condenser before i leave the home and turn on 3 hours before i come back home....

question is, SG weather is not tat cool, so what exactly is their required temperature to keep the refrigerant suitable for anytime use?

Edited September 12, 2010 by neubie

[manutd1972 1]

there are 2 sizes of piping commonly used in the market.

when one changes the condenser n FCU, one needs to check if the size of the existing pipe and the inlets/outlets of the new aircon fits each other. If so, then yes, the old pipes can be re-used.

if not, the old pipes will need to be changed.

[MichaelAng 1]

seems logical, as i have heard many pple saying it's not good to unplug the power supply to the condenser unit as it will shorten the life of the compressor for the reasons stated above...

maybe i will install one 24-hour timer to cut the supply of the condenser before i leave the home and turn on 3 hours before i come back home....

question is, SG weather is not tat cool, so what exactly is their required temperature to keep the refrigerant suitable for anytime use?

That sounds very much like our car. It needs to be warmed up before driving at higher speed. So always starts slow so as to warm up and ensure that the engine oil is of the right visocity and coated the relevant parts.

I doubt the ambient outside temperature of 30 - 37 degree is enough to warm up the liquid then especially when it cools down at night. But using a timer to on and off the compressor sounds like a good idea. The problem is that it might be hard to get a timer that would fit the electrical plugs for the compressor and it likely not using the same as normal else I can use those I am currently using for my fish tank to do the job.

[neubie 2]

That sounds very much like our car. It needs to be warmed up before driving at higher speed. So always starts slow so as to warm up and ensure that the engine oil is of the right visocity and coated the relevant parts.

I doubt the ambient outside temperature of 30 - 37 degree is enough to warm up the liquid then especially when it cools down at night. But using a timer to on and off the compressor sounds like a good idea. The problem is that it might be hard to get a timer that would fit the electrical plugs for the compressor and it likely not using the same as normal else I can use those I am currently using for my fish tank to do the job.

shd have such 24-hour (even 7-day timer) in 15A roundpin plug-type...

[wolflet 1]

shd have such 24-hour (even 7-day timer) in 15A roundpin plug-type...

my aircon is connected to an isolator box. not the 15A round pin.

[neubie 2]

my aircon is connected to an isolator box. not the 15A round pin.

can be converted one, pretty straightforward... but it is not the practice to directly connect the aircon power directly to the 20A isolator what, what happens if i need to change aircon few years down the road?

[DaveLee1688 1]

Well, sounds similar.

Note that the reply from brand M says that the heater turns on when temperature is above 21 degrees. This is my problem with the heater - In Singapore climax, it hardly falls below 25 degrees, so the heater is ON all the time in standby mode.

The Daikin reply seems to be targeted at counties with 4 seasons, which then, I do understand the heater is necessary in that climax. However, in Singapore, if the temperature gets below 21 degrees, the world will be a very different place, and by that time, my worries will not be about aircon but where to get a boat when polar cap melts further to sink Singapore

I did some digging into this heater issue after the discussion and found this post

http://forums.energymatters.com.au/energy-...y/topic594.html

The author is using a daikin aircon and states that it also contains a heater that draws 50W at standby.

He contacted the manufacturers and was told this

"After speaking to the manufacturers, I have discovered the reason is that they have to maintain a minimum temperature of the refrigerant at all times. If the fluid becomes too cool, it increases in viscosity and can damage or severely reduce the life expectancy of the compressor if it is started in that "cold fluid" situation. As a result, in order to be ready to be "instantly activated" the units have a small heater that constantly maintains the fluid temperature.

The advice from the manufacturer is that it takes at least 6 hours for the unit to warm the fluid sufficiently to allow a safe start, possibly slightly less on a hot summer day and probably more (ideally 12+ hours) in winter when the unit is very cold. However, to save this constant 50W draw, the air conditioners can be switched off at the switchboard AS LONG AS THEY ARE ALLOWED TO WARM UP FOR AT LEAST 6 HOURS OR PREFERABLY OVERNIGHT BEFORE THEY ARE ACTIVATED."

So maybe we can also consider turning on the power to the aircon 6 hours before starting to prevent damage to the compressor?

But this may only apply to certain models of daikin and probably not applicable to those being sold in singapore

Edited September 13, 2010 by mit3a28

[wolflet 1]

Well, sounds similar.

Note that the reply from brand M says that the heater turns on when temperature is above 21 degrees. This is my problem with the heater - In Singapore climax, it hardly falls below 25 degrees, so the heater is ON all the time in standby mode.

The Daikin reply seems to be targeted at counties with 4 seasons, which then, I do understand the heater is necessary in that climax. However, in Singapore, if the temperature gets below 21 degrees, the world will be a very different place, and by that time, my worries will not be about aircon but where to get a boat when polar cap melts further to sink Singapore

did they state why the heater is on only when temp is above 21? shouldn't the heater only turn on when the ambient temp is low instead of high?

[RimBlock 0]

did they state why the heater is on only when temp is above 21? shouldn't the heater only turn on when the ambient temp is low instead of high?

Must be a lost in translation issue. Clearly the heater would be needed if it was cold and not if it was hotter.

Why the aircon unit has a crankcase heater (taken from www.refrigeration-engineer.com here)

One thing that may be confusing to people is why some compressor units will have crankcase heaters installed on or in the compressor and other compressors may not have any installed. It helps to understand the overall application of the equipment and it's location.

Compressors installed outdoors in cold applications make this a mandatory requirement. During the off-cycle the compressor can cool down and allow the oil to dissolve in the refrigerant. When the compressor starts up on the next run cycle the diluted oil thins out (lower viscosity) and can wreck a compressor.

In general practice it is always a good idea to have a crankcase heater installed on the compressor. Usually when you do not see a heater installed on the compressor it is either due to:

1. Someone did not understand why they are required, or

2. Someone tried to save money!

Now I would imagine that in tropical climates it would not be required but I am not a designer of aircon units. The unit mentioned here is probably manufactured for global distribution. What would be the environmental impact of manufacturing a different unit spec for each different climate. Would the effect of doing this outweigh the electricity usage of a crank heater.

Doing a quick google around concerning crank case heaters mentions their failure as one of the main causes for aircon failure or the compressor making noises.

A few points of note on deciding if you wish to turn off your compressor when not in use.....

1. Do you turn off all your TV's, water heaters (drinking water), DVD players, Computers, Singtel or Starhub tv boxes and just about any other electrical appliance AT THE PLUG when not in use. 99% will be using standby power. We have been doing this for two months and have seen a 15-20% drop in our electrical bill.
2. The calculations bounced around here do not seem to take in to account failure rates of a compressor when not keeping the crank heater running. Having to replace the compressor is far more environmentally unfriendly than an extra few dollars electricity a month.
3. The figures here do not seem to take in to account the better efficiency of the coolant to aid cooling on start-up if a crank heater is installed and left turned on. Saving money through efficiency of cooling may well offset the cost of the crank heater running.
4. The engineers at the company who manufactured the aircon unit most likely know more about the best way to run it than you or me so maybe it is best to take their advice. Surely you (as in a general 'you' not anyone in particular) are not the type of person who googles when you are ill then demands the doctor give you a specific treatment.
5. None of the information has citations. It is all just word of mouth. If there are letters or emails etc then please publish in this thread ? Please make them available so we can all see the original responses.

If you fear flipping the RCB on a distribution box because of sparks then you really need to get the distribution box changed as there is something wrong. RCBs should never cause harm to anyone. They are designed to be used by consumers, all be it on an infrequent basis.

I have a Mit Heavy Industries 3 split system and will not be turning it off at the plug when not in use. I would suggest anyone who does also checks their warranty as using it outside of the manufactures recommendations may invalidate it.

Want to make good savings, make sure you turn off all consumer electronic devices at the plug overnight and whist at work where possible (obviously not the fridge etc).

Happy saving cash. More savings means more cash for nicer renos .

RB

[manutd1972 1]

ok, this is wat i just found out frm my aircon guy. but bear in mind, neither he nor I have any concrete numbers to back it up. this is based purely on wat his site "engineers" tell him.

1) all inverters will have this standby power drawn so long as the mains is not switched off.

2) M* brand does have a relatively high standby power usage, as compared to other brands, be they D*, P*, T* or any other inverter system.

3) if the time duration between switching off the mains and turning on the compressor to use the aircon is less than a day, it is still ok, and no significant damage is caused to the compressor. i take it that this means the compressor oil will not lose its temperature that quickly in order to effect its viscosity (thin out) and not be able to perform its function adequately.

4) if you're going to be away for a few days, u can either leave the mains on (thereby incurring standby power usage), or u can switch off the mains, but upon return, make sure u switch on the mains at least 6hrs before using the aircon.

the above is wat is told to me. perhaps someone more technically-qualified or who has the actual numbers and technology know-how can advise us, end-users. thanks.