Your Opinion of Mitsubitshi "Inverter" A/Cs

[Pib]

One of my home York A/Cs (an 18K BTU, 10 year old, fixed speed/standard A/C) has developed a major problem that going to take around Bt7K to repair (the main electronics board on the inside unit).   This York A/C has literally run almost 24/7 for the last 10 years with only a few minor repairs required and it's definitely feeling its age from hard use over the years.  Rather than repair, I plan to replace this York 18K BTU standard A/C with an inverter A/C in the 18-24K BTU range.

 

At this point I plan to buy either a Mitsubishi Mr Slim "inverter" model number MSY-GN-18VF (18K BTU) or MSY-GN-24VF (23K BTU).    Below snapshot is the approx cost of above mentioned models plus another Bt3-4K for installation.

 

My questions are: for those of you who have an "inverter" A/C, preferably a Mitsubishi inverter A/C, what do you think of them..do your recommend them?    Thanks in advance. 

 

 

 

 

[r136dg]

I didn't go Mitsubishi on our new build, but no doubt it was a neck in neck contender. All my research pointed to Mistsu or Daikin inverters. The only reason I went with Daikin is a handful of close friends that built within the last decade did & had only praise for them. One of our bedrooms has a 18,000btu that sale priced very close to the price you were quoted on the Mistu. IMO- I'm reasonably sure you couldn't go wrong with the Mistu inverter, especially at that price.

You obviously looked into the benefits of inverters when running 24/7. Be careful if running with the 24,000btu, we oversized in one room and just can't get that perfect comfort zone in there because of it.

[stevkob]

You can rest assured that your purchase of the Mitsi unit will be a good one. As the previous poster mentioned, the Daikin and Mitsubishu product are the best.

You will probably find your electricity bill will reduce if the room it serves is small and has the correct capacity requirement.

[bankruatsteve]

Inverter for sure with AC.  You can probably go down in size from conventional.

[Pib]

Thanks guys.  The room it will cool is more like three rooms. 

 

Basically it will primarily cool the dining room where the A/C inside unit is fitted on the wall...the dining room is approx 35 sq/mtrs but the dining room joins with the living room (35 sq/mtrs) and another room of about 25 sq/mtrs...both of which have A/Cs also but we rarely run these A/Cs because the cooled air from the dining room goes into these rooms through large openings between the rooms and keeps them fairly cool.  And actually the small indoor kitchen and downstairs bathroom get some cooling from the dining room also.  So I guess I really have one large "zig-zag shaped" room of over 95 sq/mtrs...and we keep the temp at around 26C for the dining room.    The dining room is the main portion to cool with the adjoining rooms just to get a secondary cooling effect.

 

Now I know 95 sq/mtrs of area needing cooling needs a lot more than 18-24K BTU cooling especially if wanting to cool down to around say 23C, but the current standard/fixed speed A/C of 18K BTU has done the job for 10 years in keeping a 26C temp "but" I know it has had to run a lot to maintain that....running a lot means a lot of compressor usage/running which means a lot of electricity usage.   

 

So, right now I strongly leaning towards the 23K BTU sized inverter...the Mitsubishi MSY-GN-24VF model.   Going larger than that starts getting pretty pricey, the compressor outside unit starts getting kinda large and my gut tells me it actually might not properly cool the zig-zag area/rooms I need cooled due to being oversized as it might sense the dining room as the only area it really needs to cool versus the two adjoining rooms also to a degree.

 

And the last time I had a A/C repair team here to do a repair that cost around Bt3K I had the Thai wife ask them in Thai what A/C inverter brand would they recommend...what they considered the best A/Cs....they recommended Mitsubishi and Daikin with the caveat that they were a little pricier than most other manufacturers.  And this repair team actually worked primarily for another major A/C manufacturer (York) but could also work other manufacturer models also.

 

Here in my large moobaan without a doubt the majority of houses have York, Mitsubishi, and Daikin A/Cs installed with York and Mitsubishi running neck and neck in quantity and Daikin not too far behind.   I think there are so many York A/Cs because the moobaan developer must have got a good deal for a large buy.   I've been happy with my 7 York A/Cs in my house and only one of them has every required any major maintenance (the one that runs 24/7), but they are now a decade old and when a major & too costly repair comes up on any of them I'm going probably going to replace them....probably with an inverter in most rooms...call it multi-year staggered replacement/upgrade program.

 

Thanks again for the feedback.

 

 

 

 

 

 

 

 

[xylophone]

22 minutes ago, Pib said:

Thanks guys.  The room it will cool is more like three rooms. 

 

Basically it will primarily cool the dining room where the A/C inside unit is fitted on the wall...the dining room is approx 35 sq/mtrs but the dining room joins with the living room (35 sq/mtrs) and another room of about 25 sq/mtrs...both of which have A/Cs also but we rarely run these A/Cs because the cooled air from the dining room goes into these rooms through large openings between the rooms and keeps them fairly cool.  And actually the small indoor kitchen and downstairs bathroom get some cooling from the dining room also.  So I guess I really have one large "zig-zag shaped" room of over 95 sq/mtrs...and we keep the temp at around 26C for the dining room.    The dining room is the main portion to cool with the adjoining rooms just to get a secondary cooling effect.

 

Now I know 95 sq/mtrs of area needing cooling needs a lot more than 18-24K BTU cooling especially if wanting to cool down to around say 23C, but the current standard/fixed speed A/C of 18K BTU has done the job for 10 years in keeping a 26C temp "but" I know it has had to run a lot to maintain that....running a lot means a lot of compressor usage/running which means a lot of electricity usage.   

 

So, right now I strongly leaning towards the 23K BTU sized inverter...the Mitsubishi MSY-GN-24VF model.   Going larger than that starts getting pretty pricey, the compressor outside unit starts getting kinda large and my gut tells me it actually might not properly cool the zig-zag area/rooms I need cooled due to being oversized as it might sense the dining room as the only area it really needs to cool versus the two adjoining rooms also to a degree.

 

And the last time I had a A/C repair team here to do a repair that cost around Bt3K I had the Thai wife ask them in Thai what A/C inverter brand would they recommend...what they considered the best A/Cs....they recommended Mitsubishi and Daikin with the caveat that they were a little pricier than most other manufacturers.  And this repair team actually worked primarily for another major A/C manufacturer (York) but could also work other manufacturer models also.

 

Here in my large moobaan without a doubt the majority of houses have York, Mitsubishi, and Daikin A/Cs installed with York and Mitsubishi running neck and neck in quantity and Daikin not too far behind.   I think there are so many York A/Cs because the moobaan developer must have got a good deal for a large buy.   I've been happy with my 7 York A/Cs in my house and only one of them has every required any major maintenance (the one that runs 24/7), but they are now a decade old and when a major & too costly repair comes up on any of them I'm going probably going to replace them....probably with an inverter in most rooms...call it multi-year staggered replacement/upgrade program.

 

Thanks again for the feedback.

 

 

 

 

 

 

 

 

Have recently installed a Mitsubishi 15k BTU Mr Slim inverter a/c in my apt and it is working like a dream........very efficient and saves on the previous elec bill.

 

Have had Samsung before and they are poor compared to the Mitsubishi.

[cornishcarlos]

I hope you have steady electric supply ? Apparently, inverters don't do spikes and troughs too well :)

[Pib]

. 

2 minutes ago, cornishcarlos said:

I hope you have steady electric supply ? Apparently, inverters don't do spikes and troughs too well :)

Yes, my electric supply is stable/clean...and I've always heard inverters A/Cs are more subject to damage from unsteady electric supply than standard A/Cs....and more costly to repair due to the special inverter electronics used.

[CGW]

I had problems with a 18k Mitsu Inverter AC that nobody could fix, including techs from Mitsu - its a long story that i did post about at one time! (we have three other Mitsu Inverters that have been no problem)

We moved that AC from the bedroom to a room that isnt used so much and replaced it with a Daikin inverter, the Daikin is far superior, in future any new AC I buy will be a Daikin

[stevkob]

In lieu of the larger capacity you are hoping to meet I would also recommend you go for the 24VF model. And I take back what I said about expecting any power bill savings :)

[Pib]

26 minutes ago, stevkob said:

In lieu of the larger capacity you are hoping to meet I would also recommend you go for the 24VF model. And I take back what I said about expecting any power bill savings :)

Actually it still should save on my electric bill because its max running current when using all its 23K BTU capacity is 8.6amps which is the same at the 8.6A running current of my 18K BTU standard A/C.  However, the invertor will not be running at full capacity...says it backs off to 10K BTU once it cools down the area which means it's running current/amperage will be much lower....which means lower electric bill.  

 

 

[bankruatsteve]

From my experience (which is a 9K BTU Mitsu conventional replaced by a "12K" Daikin inverter (the manual says up to 11K something BTU), the inverter typically runs at about 35% of the power draw that I measured on the Mitsu.  It's pretty much the same at start-up but the inverter will reduce power draw within about 30 min.  And, I have never come close to the BTU/hour rating of either unit as measured by my watt meter - so I don't know how they come up with the rating if my units are any example.

[Pib]

An inverter can vary its BTU output from its minimum to maximum....which varies it power usage....that's how it saves on electricity used.  For an 18K BTU an inverter's maximum BTU output will usually be around 20K BTU and its minimum around 5K BTU.

 

When the inverter A/C starts up if the room is hot its going to run towards in max BTU capacity if necessary and once the room starts cooling down the inverter will back off its BTU output...like maybe back-off down to its minimum of around 5K BTU as the room temp stabilizes...or it maybe stabilize somewhere between its min and max BTU rating as needed to maintain whatever the temperature setting is...like maybe stablize around 10K BTU, or 8K BTU,  or you fill in the blank.

 

Below is a snapshot from the Mitsubishi catalog regarding show the key BTU/Wattage/Amps specs for its inverter A/Cs.  Notice how each has a "nominal" max BTU rating like 18K BTU which it's advertised/sold as and its model number is based on.  However, it's BTU output will actually exceed that nominal rating by X-amount...maybe around 10% more and go all the way down to around 25% of it max BTU output.    For example the 18K BTU inverter capacity can vary from a little over 5K BTU up to around 20.4K BTU as it operates to cool the room.    Only use/vary the BTU capacity compared to a standard A/C that always put out its max BTU when the compressor/outside unit is running.

 

The Running Current rating is really the running current at its nominal rating...the current drawn will be less when running at it lower BTU capacity, etc.    And in the Input Power Rating area you see how the wattage used varies from a min to a max as the BTU output would vary from a min to a max.

 

 

 

[Pib]

10 hours ago, r136dg said:

You obviously looked into the benefits of inverters when running 24/7. Be careful if running with the 24,000btu, we oversized in one room and just can't get that perfect comfort zone in there because of it.

 

Since an inverter A/C can vary its BTU output...and I expect your 24K BTU inverter A/C could lower its output down to around only 5K BTU if required....or anything between around 5K to 25K BTU, can you expand a little bit on what you mean by "...just can't get that perfect comfort zone in there because of it." 

 

I can understand an oversized standard/fixed speed A/C causing such an issue, but how would an inverter cause that that issue since it could act like a much smaller or just right-sized A/C. 

 

Not arguing it didn't happen with you...just want to get a better idea of what you mean by not being able to get the perfect comfort zone, how the A/C operated, etc.  Thanks.

 

 

[tutsiwarrior]

I've had a 24kbtu Mitsibishi 'Mr Slim' inverter unit installed for a year now...and very happy with it...it cools the downstairs of one of our shop houses...I also use a pedestal floor fan to help distribute the cold dehumidified air in a 4m x 12m space with a 3m ceiling...

 

one thing I noticed when we had the unit cleaned after 6 months of service was that the evaporator (indoor) coils were unbelieveably filthy and there's no hard duty that would account for this...I'll just havta keep to a strict maintenance schedule, I suppose...

 

 

Edited January 2, 2018 by tutsiwarrior

[maxpower]

The worst scenario for proportional control would be to under size a unit to the point where it rarely drops below full output.

 

Inverters have conversion loss which makes them less efficient than a conventional AC when running at full output. They must run at reduced output for long enough periods to justify additional cost. 

 

It should also be noted that most modern conventional AC employ accurate PID control even though its ON/OFF. They are not that inefficient when compared to an inverter controlled equivalent. The sales BS will often quote crazy laboratory percentages.

 

Inverter controlled refrigerators are a good example of accurate output matching which results in high efficiency.
 

[stevkob]

7 hours ago, maxpower said:

Inverters have conversion loss which makes them less efficient than a conventional AC when running at full output. They must run at reduced output for long enough periods to justify additional cost. 

 

And this why I commented as to the lack of energy bill reduction, the 95m2 area you wish to keep cool is too large for the unit to effectively do it's job and will most likely most of the time be running flat out.

 

Having said that, in practice there are many installations that have undersized units operating and the occupants are quite satisfied with the cooling effect they receive. So I am confident you will be pleased with your new unit purchase.

 

[r136dg]

12 hours ago, Pib said:

 

Since an inverter A/C can vary its BTU output...and I expect your 24K BTU inverter A/C could lower its output down to around only 5K BTU if required....or anything between around 5K to 25K BTU, can you expand a little bit on what you mean by "...just can't get that perfect comfort zone in there because of it." 

 

I can understand an oversized standard/fixed speed A/C causing such an issue, but how would an inverter cause that that issue since it could act like a much smaller or just right-sized A/C. 

 

Not arguing it didn't happen with you...just want to get a better idea of what you mean by not being able to get the perfect comfort zone, how the A/C operated, etc.  Thanks.

 

 

Being in a hurry & listening to a very confident installer I took his word for the sizing of a bedroom. It turned out to be oversized and the repercussions are I can't get the same performance I get out of rooms that are sized properly. I like 27c & the rooms sized properly will be right in my comfort zone on 27c cool or dry. The oversized room will not. Dry setting or 27c cool setting leaves the room humid, like there's no ac in the room at all. The only way to get the humidity out of the room is to turn it down on the cool setting to 25c, a little nippy for my wife.

Anyways, that's how oversizing impacted us. Hope it helps.

[simoh1490]

Mr Slim units are very sturdy and reliable, I have three of them.

[Pib]

2 hours ago, stevkob said:

 

And this why I commented as to the lack of energy bill reduction, the 95m2 area you wish to keep cool is too large for the unit to effectively do it's job and will most likely most of the time be running flat out.

 

Having said that, in practice there are many installations that have undersized units operating and the occupants are quite satisfied with the cooling effect they receive. So I am confident you will be pleased with your new unit purchase.

 

I totally agree a 24K BTU inverter is too small to evenly/fully cool a 95 sq/mtr area, especially if it was was just one large rectangular/square area which it is not, just as my current 18K BTU is too small for a square/rectangular 95 sq/mtr area, but has still done the cooling job to our satisfaction for a temp setting of 26C since it's a zig-zag shaped area.

 

As mentioned earlier this area is really three separate rooms interconnected with large interconnecting openings approx 2 meters wide between the rooms.   It's not just one "rectangular/square"...that's why I called it a zig-zag room arrangement.    That zig-zag arrangement limits how much cool air overflows into two rooms from the room with the A/C.

 

The A/C is mounted in one room in such a way that it evenly/fully cools that room--and that is what the A/C temperature sensor monitors to determine when to cut A/C on and off.   Now since two more rooms connect to that room with the A/C, a good amount of cool air flows into them also....maybe call it overflow from the room with A/C.  And this overflow does a good enough job to keep them cool enough especially with a couple of floor fans moving the air around.    

 

Now the overflow (loss) of cool air from the room with the A/C of course makes the A/C work harder to cool that room down due to loss of cool air into the other rooms, but that A/C still is using the sensed temperate in that room to control its operation.  Iit does not sense the temp in the two adjacent rooms that are getting overflow cool air.    So when the temp in the room its located in reaches 26C it cuts off; the temp in the other two rooms is probably going to be around 27C and 28C based on their location in the zig-zag shaped room.   Turn the temp setting down to 25C in the room with the A/C and the other two rooms will get down to around 26C and 27C.  

 

And I could go on talking about where the A/C is currently placed in the room would really do a better job in cooling these areas if it had been originally placed in another room based on our living arrangement within the house....where we spend most of time, day and night.   But that is water under the bridge now since the A/C wiring was predesigned into the house.   And I will have to admit for the dining room where the A/C is mounted on the wall that is the "only" location it could have gone based on the design/shape of the room.   

 

If I had it to do all over after living in the house for almost 10 years now and taking in account how we live int the house, where we spend most of our time, etc.,  the three A/Cs I have installed downstairs would still be installed in the same locations (no real choice due to electrical wiring/room design), but I would resize two of the three A/Cs.  Make one larger and one smaller BTU-wise and flip the amount of usage I give each.    However, to do that now would require buying "two" new A/Cs (the one I'm replacing right now and one that is still working perfectly fine), some minor construction, etc.,...probably just not worth it. 

 

So, in buying this 24K BTU inverter which is really too much for the room it location in, it has a dual duty of all cooling "to a degree" to connecting rooms that will bleed off some of its cool area.  By the way I haven't fully decided on a 24K BTU size year as I'm actually struggling in deciding between an 18K or 24K sized inverter because of the reasons I've covered above...but I'm leaning more towards the 24K BTU size.

 

Yea, if I could go back in time during the original installation of the downstairs A/C and say, No, do this instead because of these reasons.   :)

 

Cheers and Happy Holidays.  And big thanks to all who have given great input....it's much appreciated.

 

 

 

 

 

 

  

[Pib]

2 hours ago, r136dg said:

Being in a hurry & listening to a very confident installer I took his word for the sizing of a bedroom. It turned out to be oversized and the repercussions are I can't get the same performance I get out of rooms that are sized properly. I like 27c & the rooms sized properly will be right in my comfort zone on 27c cool or dry. The oversized room will not. Dry setting or 27c cool setting leaves the room humid, like there's no ac in the room at all. The only way to get the humidity out of the room is to turn it down on the cool setting to 25c, a little nippy for my wife.

Anyways, that's how oversizing impacted us. Hope it helps.

Yea, sure does. 

 

I'm fairly sure these generic-BTUs-needed-to-cool-so-many-square-meters-ratings that A/C manufacturers/installers use to develop their EER/SEER specs for an A/C  and for BTU room size advertising purposes is based on an indoor temperature of 27C.  But even using various BTUs needed calculators on the web can give widely varying recommendations since they all seem to use different formulas and data input to make their recommendation.

 

I'm just somewhat surprised an inverter A/C which can downshift its BTU cooling capacity...usually down to around 5K BTU for commonly used inverter A/Cs that most any inverter A/C could end up being over-sized if a person selects a 27C or lower indoor temperature.  But the devil is always in the details of exactly how the A/C design, its circuity/programming, the room itself, etc.   Preaching to the choir I know.   Cheers.

[Pib]

Thanks to everyone on their input.  Today I ordered the 23K BTU Mitsubishi invertor model # MSY-GN-24VF with a planned install date of this Sunday assuming the installer gets back from New Years vacation on time.   Ordered it from the same company here in Bangkok I used to buy my York A/Cs from 10 years ago.   

 

Product price: Bt35,800 plus another Bt3,000 install....total Bt38,800.  

 

That Bt38,800 price with full Mitsubishi warranty sure beats the price of big box stores like HomePro, PowerBuy, etc., where the A/C goes for around Bt10K more at around Bt50K (includes install) give or take a little.   One thing I found out over the last year in comparing air con prices is you will "not" get the best/lowest cost deal at a Thailand big box store no matter how fantastic they make a sale sound.   In my shopping around in big box stores here in Bangkok for this particular model the lowest price I found (including install cost) was Bt46,000 and I think that was at PowerBuy in the Central Pinklao mall.

 

If Bought At HomePro (includes install cost)

 

Edited January 4, 2018 by Pib

[lopburi3]

On 1/2/2018 at 9:04 PM, tutsiwarrior said:

I've had a 24kbtu Mitsibishi 'Mr Slim' inverter unit installed for a year now...and very happy with it...it cools the downstairs of one of our shop houses...I also use a pedestal floor fan to help distribute the cold dehumidified air in a 4m x 12m space with a 3m ceiling...

 

one thing I noticed when we had the unit cleaned after 6 months of service was that the evaporator (indoor) coils were unbelieveably filthy and there's no hard duty that would account for this...I'll just havta keep to a strict maintenance schedule, I suppose...

 

 

Extremely dirty is an understatement - I can not get more than 5 months service from a small unit in grandchildren's bedroom.  There are 2 teenage girls in room so expect that may have something to do with it - but never had to clean this often with normal units.  Would not be buying another inverter of this brand.  ((and yes be keep filters cleaned))

Edited January 8, 2018 by lopburi3

[Pib]

Many people are surprised in how dirty (and how quickly) an A/C can get evne when the filters are cleaned frequently/once a month or sooner....both the inside and outside unit. 

 

I live in western Bangkok....no construction going on close to me or dusty roads to cause dust to be in the air.   We use A/Cs 24/7 with no doors or windows opened; therefore, there is no stuff from the outside to blow into the house to contribute to making the inside unit dirty.  And the wife is clean freak!   I mean she is always cleaning the house...mopping...vacuum cleaning...dusting for dust that barely exists, etc.  We have one dog which is a short hair dog.  We don't smoke.  The kitchen is in a separate room. 

 

I clean the A/C inside units twice a year and the A/C's outside unit once a  year.    I'm always amazed in how dirty the A/Cs get,especially the inside unit cage fan....the spinning cage fan you can see with a flash light when looking into air output vent.   And when that cage fan gets dirty/grimy it's air pulling/pushing capacity is very significantly reduced which means less air is pulled through the cooling fins/coils and less cool air can be pushed out into the room. 

 

And this reduced cooling capacity causes the whole A/C system to work harder to cool....especially the outside unit/the compressor where over 90% of your A/Cs power  usage is consumed.   And I found cleaning the outside unit once a year is enough...twice would be good but not really required especially if it's kinda hard to get to like mount up on the house wall.  But when its too dirty it will really cause your compressor to work really hard....really consume a lot more energy.  And I'm talking about my location in Bangkok...if out in the provinces cleaning the outside unit twice a year is probably a good idea as their is more dust and stuff floating around in the air.

 

I saying this based on 10 years of experience with the 7 York A/Cs I have in my house and I have maintained/cleaned over those 10 years....and closely watched their energy consumption like monitoring the ammeter on my main circuit box to check the current/power usage of each A/C as I know what each one normally draws amperage-wise from its specifications and just monitoring them over the years.   I can literally tell from the current draw how dirty the A/C is or isn't.    

 

Summary regarding a dirty A/C: I think you will find all A/C can get dirty pretty easy even in a home/room kept clean, a non-smokers room, non-cooking room, etc.  

 

But as of this Monday afternoon I now only have 6 York A/Cs as that Mitsubishi Inverter 23K BTU A/C was installed and running as we speak..replaced a York 18K BTU standard A/C.   Right now I still trying to learn its controls, figure out the Star Trek remote control, and various things.  It runs so quite, especially the outside compressor unit.  It's a very quite 23K BTU inverter A/C...and lot more quite than the York it replaced.  I'm monitoring it's amperage draw with the ammeter on the the house circuit breaker box and at around 7pm tonight it was using around 25% less amperage than the standard/fixed speed 18K BTU it replaced.  And right now at around 8pm its using around 40% less than what the York standard A/C would be drawing at this time & outside temperate.   As mentioned, I've watched the amperage draw of my A/C closely for 10 years so I know what they normally draw during the day and night at various temperatures.  Anyway, so far, so good with this new Mitsubishi Inverter 23K BTU.  Cost  Bt35.8K plus Bt3K install for a total of Bt38.8K...the installer did a good job...I watched him and his helper closely as they did the install today.

 

In closing, I asked the installer today what A/C brands he thought were the best.  A gentlemen around 50 years old, been installing/repairing A/Cs for many years in residences and businesses.   Tied for his number 1 ranking were Mitsubishi and Daikin....he felt they were equal and the best.   And then his next choice was Carrier followed by Trane.

 

Edited January 8, 2018 by Pib

[mindovermatter]

Mitsubishi and Daikin are very good AC brands so the difference between them may be very minimal. 
 

[tutsiwarrior]

17 hours ago, mindovermatter said:

Mitsubishi and Daikin are very good AC brands so the difference between them may be very minimal. 
 

 

yeah...I wanted to get a daikin but there wasn't one available in the size I wanted (24kbtu) so I got the mr slim instead...paid about the same as Pib for his unit but the installation was included in the price...from a 'big box store' up at the changwat; bought a 4.8kw shower water heater and a small TV at the same time and they gave me a free toaster which was handy as the old one played out when I got home right after I retired...

 

now that I remember it's just about time to clean the unit again according to schedule but it hasn't had much use during the past couple of months...just keep the fan goin' to circulate the air...

 

 

[Pib]

Some very preliminary feedback on the Mitsubitshi MSY-GN-24VF (23K BTU) on energy savings after having monitored/compared the energy usage over a 24 hour period with past energy usage.   

 

I have logged my monthly electricity usage since moving into my Bangkok house over 9 years ago.  I know exactly how many KiloWattHours (KWH) I've used each year and for each month.  

 

When I look at last year's bill for this time period and do some math to convert it to a daily average Kwh used I get 54.68Kwh/day.   If I use 2 years worth for this time of year I get 54.26Kwh/day....for 3 years 50.62Kwh....for 9 years 53.34Kwh.   The temperature setting I've always used on my A/Cs over these periods is 26C.

 

When I looked at the amount of electricity I used from yesterday morning at 11:20am to this morning at 11:20am I used exactly 36Kwh.  During this period the A/C was set to 25C, one degree cooling than my normal setting of 26C.  I expect if I had set the inverter to the same 26C the usage yesterday would have been a little less than 36Kwh.   

 

Anyway, using above past daily average Kwh usage and amount used over the 24 hour/1 day period mentioned above, I get the following percentage savings:  

- Based on past 2 years average: 34% savings

- Based on past 3 years average: 29% savings

- Based on past 9 years average: 32% savings

 

I was kinda surprised my electricity savings was right around the 30% savings that A/C inverter manufacturers always advertised.    But 1 day of current usage data is not very much....I will recalculate some numbers after 3 and 7 days of usage, but I expect it going to come out right around 30% savings.

 

So, what does a 32% monthly savings (based on my 9 years of past usage during this time of year) mean to me baht-wise based on my typical electrical bill?  This is a cooler time of year so my monthly bill is usually a little over Bt6,000...during the hot months it's been around Bt10,000.  This means a 32% reduction of Bt6,000K would reduce that bill by $1,920....and reduce a month bill of Bt10,000 by Bt3,200.   

 

Let's say I end up with an average savings of Bt2,500/month over a typical year  To recover the total Bt38,800 spent to buy and install the inverter A/C it will take me 15.5 months to recover that cost....not bad, a pretty fast payback period.

 

So far, so good.  And I have to repeat the inside and outside unit are so, so quiet.  

 

 

[maxpower]

1 hour ago, Pib said:

Some very preliminary feedback on the Mitsubitshi MSY-GN-24VF (23K BTU) on energy savings after having monitored/compared the energy usage over a 24 hour period with past energy usage.   

 

I have logged my monthly electricity usage since moving into my Bangkok house over 9 years ago.  I know exactly how many KiloWattHours (KWH) I've used each year and for each month.  

 

When I look at last year's bill for this time period and do some math to convert it to a daily average Kwh used I get 54.68Kwh/day.   If I use 2 years worth for this time of year I get 54.26Kwh/day....for 3 years 50.62Kwh....for 9 years 53.34Kwh.   The temperature setting I've always used on my A/Cs over these periods is 26C.

At our BKK data center we monitor and log outside and inside temp to calculate efficiency because the outside temp has a dramatic effect on how much energy is required to cool some areas. 2017 had some really high peaks which are reflected in outside temp data and cloud cover.  

[Khun Jean]

For larger areas, especially no rectangular ones, i prefer to use more then one aircon.

In one scenario (office) we changed one older 24.000 BTU with two 9000btu inverter ones.

This gave more control as the cooling needs were not always the same. Especially when there large changes in the number of people occupying the space. Most of the time one unit was sufficient and sometimes two.

The reduction in electricity was huge.

For 95m2 this solution might also work. Place them strategically so that the airflow is exactly where you need it. With only one unit that is very difficult. 

[Pib]

Yea, in the 95m2 irregular shaped area (actually three rooms which are have large wall opening between each other which kinda make it one, big area) I have a total three A/Cs.  One in each room. 

 

Up until I installed the 23K BTU inverter in the room we spend our most time in and which is the largest of the three rooms I had an 18K, 18K, and 12K BTU fixed speed/regular A/Cs among those three rooms.   Running all three at once was just too much in terms of cooling need and electricity usage.   And the most we ever run at once was the two 18K BTU A/Cs when having visitors for a couple of hours to provide more even cooling.   Otherwise, it was just running the one 18K BTU in the dining room.

 

With just the wife and I just running one of the three A/Cs was generally enough cooling....and it was almost always the 18K BTU A/C in the dinning room area which cooled that area well and cool air overflow into the other two rooms did a good enough job to keep those two rooms cool enough.   Running just the other 18K BTU A/C in the living room did not work as well to cool all three rooms but was acceptable....just an area shape issue.   And the 12K BTU in the third room just wasn't big enough for this large area, but was OK in a pinch.  It was just simply the irregular shape and total size of the three-room area which resulted in the 18K BTU in the dining room area doing the best job when cooling all three rooms/the entire area and generally keeping us cool enough....cool enough only needing to run one 18K BTU for this 95m2 area versus running three A/Cs totalling 48K BTU.

 

But now the primary 18K BTU fixed speed A/Cs has been replaced with the 23K BTU inverter A/C as of Monday afternoon.  It's now Friday morning and that inverter A/C has not been turned off....has run 24 hours a days since Monday afternoon.   It's doing a great job of cooling to our desire the entire 95m2 irregular shaped area...and definitely using less Kwh than when I had the fixed speed 18K BTU doing that cooling....and the inverter A/C inside and outside unit are so quite.  After I have run the A/C for around 7 to 10 days I'll give some more electricity savings feedback.

 

Yeap, definitely agree in most cases having multiple, smaller BTU A/Cs for odd-shaped or long rooms/areas versus one large A/C would probably provide better/more even cooling and lower electricity usage.    Picking the right amount of BTUs really needed and how many A/Cs are needed to provide that BTU cooling definitely depends on more than sheer total size....a person needs to also look at the shape of the area, when and how people use that area, and just a whole range of considerations that can vary from person to person....even whether a fixed speed or inverter A/C might be the better choice. 

 

If you are only going to cool the area for a few hours each day,  turn that A/C off & on numerous times during the day, or just using the A/C occasionally going with a fixed speed A/C would probably be the better choice to get the quicker cool down, lower upfront cost, and probably less repair bills over the long term.   But if using an A/C a good amount, definitely go with an inverter A/C.