Thinking of getting a new A/C? Here's an interesting paper - Inverter vs Non-Inverter

[Crossy]

We all "know" that an inverter A/C can save on A/C energy consumption.

 

Here's a paper on a reasonably well controlled experiment to demonstate that yes, you could save 49% on your aircon energy! I know it's based in KSA but it's actually the most controlled / realistic demonstration I've found to date.

 

Almogbel2020_Article_ComparisonOfEnergyConsumptionB.pdf

 

[Tom H]

….but the compressor needs power:). (vrv).

Edited March 18, 2022 by Tom H

[sometimewoodworker]

13 minutes ago, Tom H said:

….but the compressor needs power:). (vrv).

And the point you are making with that blindingly obvious statement is?

[Crossy]

34 minutes ago, Tom H said:

….but the compressor needs power:). (vrv).

 

I'm a bit confused by this statement, particularly because it's the compressor which has the "inverter" bit controlling its speed.

[tonray]

I did not look at the full data sheet but the graphic states this was done in Saudi Arabia, where the climate is typically very hot but also dry. I wonder if the same savings (or more) might be realized with an environment where the dewpoint temp is very high, such as Thailand. Interesting.....We have inverters in 3 rooms (about 3 years old) and I'm quite happy with their energy use profile, monthly bills are quite reasonable, in most months less than I was paying in a small condo with an older unit previously.

[Etaoin Shrdlu]

We replaced four twenty-year-old Mitsubishi air-conditioners with new units that have inverter technology. The old units had been cleaned and maintained properly. There was a noticeable drop in our electricity bills after the switch.

[Crossy]

18 minutes ago, tonray said:

I wonder if the same savings (or more) might be realized with an environment where the dewpoint temp is very high, such as Thailand.

 

Condensing water out of the air certainly gives up energy which must then be pumped away.

 

Just how much that would reduce the efficiency would be interesting to calculate. Task A. Measure how much water your A/C condenses in a 24 hour period ???? 

[Crossy]

13 minutes ago, Etaoin Shrdlu said:

We replaced four twenty-year-old Mitsubishi air-conditioners with new units that have inverter technology. The old units had been cleaned and maintained properly. There was a noticeable drop in our electricity bills after the switch.

 

We recently replaced the 2012 vintage x 18,000 BTU conventional unit in our bedroom with a 12,000 BTU inverter. Of course it's a smaller unit, but since it's producing the same cooling the numbers should be comparable.

 

We keep a detailed log of consumption (an entry every 60 seconds) because I'm a sad individual. Crunching the night time figures does reveal a noticeable reduction, and because there are no start-up spikes our solar inverters should be rather happier too ???? 

[sometimewoodworker]

15 minutes ago, Crossy said:

We keep a detailed log of consumption (an entry every 60 seconds) because I'm a sad individual.

So since I record every visit to the petrol station with, mileage, trip mileage, car’s reported trip consumption, fuel price and volume, in a spreadsheet that then computes a bunch of other numbers like overall fuel cost and usage per km and exactly how much a the car costs per km driven (฿32.91) and for fuel (฿1.793) all that makes me an equally sad individual? ????

[bankruatsteve]

Not only AC.  Washer and especially refrigerator will have similar savings.

[tonray]

4 minutes ago, bankruatsteve said:

Not only AC.  Washer and especially refrigerator will have similar savings.

Yes...except our refrigerator's savings are mitigated by the GF standing there with the door open for 10 minutes deciding which fermented fish product will go best with her kilo of rice.

[KhunLA]

50 minutes ago, tonray said:

I did not look at the full data sheet but the graphic states this was done in Saudi Arabia, where the climate is typically very hot but also dry. I wonder if the same savings (or more) might be realized with an environment where the dewpoint temp is very high, such as Thailand. Interesting.....We have inverters in 3 rooms (about 3 years old) and I'm quite happy with their energy use profile, monthly bills are quite reasonable, in most months less than I was paying in a small condo with an older unit previously.

Interesting, as using 1 non, in bedroom now, on 16 ish hours a day, at least, and bill is 2500 usually, 2900 thing month, 5-600, almost 700 PEA units this month.   No real cool season, PKK.

 

Old house, 3 non, again, 16 hr a day, had a cool season (Udon Thani), and high bills, 1200 units / 5000 baht.

 

New house will be 2 inverters, and expecting to double the bill, at least, using 1200 units a month, though most will be solar, so ROI should be quick, 5 ish yrs.  Be interesting to see AC savings, and now, one 9 or 11k BTU unit.  New house, one each 18k & 24k BTU units, with both unit probably running 12 hours daily.

[KhunLA]

22 minutes ago, sometimewoodworker said:

So since I record every visit to the petrol station with, mileage, trip mileage, car’s reported trip consumption, fuel price and volume, in a spreadsheet that then computes a bunch of other numbers like overall fuel cost and usage per km and exactly how much a the car costs per km driven (฿32.91) and for fuel (฿1.793) all that makes me an equally sad individual? ????

Yea, I'm constantly crunching #s also, especially when something new.  Crunched the #s for the MG ZS different fuels / driving, E85/20/91.  So happy designed for E85.  Drones, different batteries, flight time, battery C rating, different craft weights / modifications.

 

Can't manage money if you don't know where it's going.   People should keep track of every expense for 3 to 6 months, and they'd be amazed at what they actually spend it on.

 

USA, my dining out budget was more than most of my peers income ... ????  Where my mandatory living expenses, were probably 1/4 of theirs, since usually single, no kids, and rarely had to pay for housing, being a 'slum lord', paid the mortgages and afforded me a free apartment to live in.  Didn't make monthly income, but built equity really fast.

[sometimewoodworker]

11 minutes ago, KhunLA said:

Crunched the #s for the MG ZS different fuels / driving, E85/20/91.  So happy designed for E85.

I’m currently checking between the 2 recommended fuels E20 & 95. It’s clear that 95 gives better fuel consumption but I don’t drive enough to have enough datum points yet to do the calculations for cost while smoothing out for different trips. It is looking as if 95 is actually cheaper despite its higher price. 

[thaisail]

I have had my three Samsung double inverter copper coil 12,000 BTU split unit aircons for more than one year now. Because we live in a more temporate location in Thailand, Chiang Khan, we do not run any AC from December to March. For the rest of the year, we start out running the AC in the living room in the afternoon and by sunset, the AC is no longer needed. However in the bedroom, we start using the AC as soon as the night time temperatures are staying above 22. 

 

Before going to bed, I put the remote mode on "fast". This will set the temperature at 16 and the fan and compressor will slowly ramp up to maximum rpms. I leave this setting for maybe 10 minutes until the room is cooled off. I have found that with the new technology Samsung Inverter AC's, that if I set the remotes on "quiet" which will slow down the fan until the minimum RPM and direct the cold air direct to the bed, I can set the night time temperature to 25 and with a thick sheet or light blanket, the AC will keep us at the maximum comfort. The fan is so quiet and the compressor is running at minimum rpms until the night time temperatures reach around minumum of 30 and the compressor will start to speed up slowly but the fan will run at minimum speed all night and the room is going to stay at 25 all night. I set the timer on the remote to stop the AC at 7 am and the room slowly warms up to the ambiant temerature in the rest of the house. 

 

The main reason that the inverter technology is more efficiant has to do with the laws of thermodynanics. If your AC compressor is always running at a very slow speed, the thermostat is keeping the temperature at a steady temperature which will be controlled by the speed that the compressor is turning. With the old style AC units, the compressor will run at maximum until the temperature reaches say 24. Then the compressor will stop until the temperature reaches the cut in temperature of say 26. This will give an average temperature of say 25. The major loss of efficiancy is the energy required to lower the room temperature by 2 degrees about 10 to 20 times per 24 hours. With inverter technology, this does not happen and therefor this energy loss does not occur. 

 

The other big energy is the compressor starting current with is around 6 times the current required to run the compressor. So if the compressor starts 10-20 times per 24 hours, this starting surge will start adding Kws to your meter and your total power consumption will be higher as a result. With double inverter technology the compressor and the fan will both have what is called a soft start. This surge will be far lower because the speed of both will gradually increase and this will avoid that massive surge that comes with a traditional AC compressor. You will also save money when you build a house because the cross sectional area of your conductors can be less since your amp draw will be lower because of the lack of surges when thing start direct on line.

 

But for me the best reason to go with inverter is the noise. I really like the Samsung system because when I run the AC's in "quiet" mode, there is almost no noise either inside or out. Unfortunately I found out that Daikin was the first company to have the patent on the inverter technology so they have had a 10 year period where they were either the only one selling these units or other companies had to pay a license fee to use this technology. I think this 10 year pattent has now run out and all the companies can now sell inverter technology. So Daikin has has a 10 year head start on this technology and by luck the double inverter 9000 BTU until in our bungalow, where we lived during construction of our new house was really the gold standard. I wish I had known this information about Diakin patent before I ordered the Samsung AC's. Perhaps by now the other companies have developed better technology than Daikin but one thing I like better about the Diakin is that I can adjust the temperature settings by 0.5 degrees increments instead of 1 degree like my Samsung units. This is only a matter of comfort so that if 25 is too hot we can set the room at 24.5 degrees and end the argument with the wife. 

 

The only disadvatage I can see with inverter technology is the extra cost to buy the AC units. But it seems that this cost difference has decreased over the last several years because they are now selling more inverter units than the classic type and the companies have gotten back their research and develpment cost. The other reason is of course repair and maintenance. Because the technology is new, many AC repair technicians are not familiar with them so finding a qualified repair man can be a chalenge in remote areas of Thailand. This problem will eventially go away as inverter technology takes over the market the same as happened already with diesel engines that went to electronic common rail from the classic mechanic deisel engines from the old days. The Thai mechanics had to learn common rail quickly. 

 

But there is one thing that is absolutely critical for using this new inverter technology. You must have a clean power supply. I have installed a high and low voltage safety switch that will trip the entire house power if the voltage goes below 190 volts or higher than 250 volts or If my amps go higher than 40 amps, the entire house will black out and with all of these functions, the power will automatically be restored when the electricity supply returns to normal with a built in timer. I fitted MOVs on my power inlet to deal with lightning surges. The cost the adjustable voltage protector with digital display and timer for the entire house is only 400 baht and the MOV's was less than 135 baht, both with Lazada. Without these feature you may be having to replace your inverter AC units or at least having very costly repairs. 

 

The second very important thing to do when changing from classic to inverter technology is make sure that the earth connection is using the same size condutor as the phase and the neutral. This is really critical the safe and efficient function of inverter technology. Make sure that your earthing rod is 2.5 meters in the ground and goes into wet earth so that there is a very good earth connection and of course, earth fault protection with no more than 30 mA trip setting. I have had a nightmare getting my electrical contractor to conform to these specification and I had to watch him like a hawk to get this done. In fact, he tried to cheat me by not even having an earthwire from the three new Samsung AC units. I had in the end have to have him put conduite around the outside of the house with separate earth wires of the correct cross sectional area going to the earth rod direct which cost me a lot of extra money but it had to be done. 

 

Anyway I just wasted the entire morning writing this essay when I should have be out intalling the new faucets that need to be installed but writing this was better then going outside to work in the hot sun! My wife does not agree!

[Tom H]

On 3/18/2022 at 7:16 AM, sometimewoodworker said:

And the point you are making with that blindingly obvious statement is?

Compressor goes on off 30 times a day. On/Off is connected with a higher electricity:)…Read long commend below from other guy. Sorry for writing short.

[Longwood50]

We replaced two units that were about 15 years old with inverters.  The first one failed and we replaced it with a 12,000 BTU LG.  It is OK but I wished I had gone with a Daikan.  When the unit failed it was the one the service technician had in stock.  It does not blow as cold air and it spits water from the fan blades on occasion which leads to a mold buildup.  

The unit in the living room was huge 33,000 BTU and it was far larger than needed.  Replaced it with a 20,000 BTU top of the line Daikan and very pleased. 

Electricity bills dropped from about 4,600 per month to between 2.200 and 2,500 per month.  This was 16 months ago so soon the Daikan will be paid for and within another year both units will have recouped enough in energy cost to pay for themselves. 

Wish I had done it years ago. 

[Crossy]

19 minutes ago, Tom H said:

Compressor goes on off 30 times a day. On/Off is connected with a higher electricity:)…Read long commend below from other guy. Sorry for writing short.

 

The whole point of an inverter unit is that the compressor doesn't cycle on/off. It dynamically adjusts its output as required by the needed cooling, very rarely actually switching off (most inverter units have a minimum cooling level at which they do power off the compressor).

 

Also inverters are "soft starting" so there's no large switch on surge, this is nice if you have solar or a genset.

[Tropicalevo]

On 3/18/2022 at 7:46 AM, Etaoin Shrdlu said:

We replaced four twenty-year-old Mitsubishi air-conditioners with new units that have inverter technology. The old units had been cleaned and maintained properly. There was a noticeable drop in our electricity bills after the switch.

Same for me and I pay 9 baht per unit for electricity. A big saving.

And the inverter unit is much quieter.

No science behind my comment. Just an observation.

[sometimewoodworker]

56 minutes ago, Tom H said:

Compressor goes on off 30 times a day. On/Off is connected with a higher electricity:)…Read long commend below from other guy. Sorry for writing short.

Talking about an inverter, no it doesn’t, so writing both short and wrong? 55555

it goes on when you switch the AC on and off when you switch it off

 

So it is technically possible to switch the AC on and 30 times a day though that would be incredibly strange behaviour, negating the AC’s thermostat control.

Edited March 19, 2022 by sometimewoodworker

[david555]

But they are more expensive buying (consider cheap Thai elec.) and the electronics more touchy , so in case of repairs more expensive they told to me.....so as always pro's and con's....????

 

 

[soi3eddie]

I installed new Daikin Inverter A/C's to living room and main bedroom in 2019/20 to replace original non-inverter units that were over 10yrs old. Was able to get bigger BTU for same physical condenser size (compressor units a bit bigger though). Therefore the replacements inside fitted perfectly where the old ones had been. Upshot is that the extra capacity can cool the rooms faster and (by my thinking) is less taxing on the units. Therefore longer life perhaps? Either way the new units are much, much quieter and the energy savings dramatic. My electric bills dropped by about 30-40%. Now I'm thinking about replacing a 13yr old fridge freezer that is non-inverter and gets very hot on the side panel at times. Anyone here have any experience with the Samsung inverter fridge freezers and their efficiency?

 

[bankruatsteve]

18 minutes ago, soi3eddie said:

Anyone here have any experience with the Samsung inverter fridge freezers and their efficiency?

Yes.  Large side by side bought 7 years ago.  Hardly shows up on energy meter.  Nothing gets hot.  Consistent temps.

[david555]

1 hour ago, soi3eddie said:

I installed new Daikin Inverter A/C's to living room and main bedroom in 2019/20 to replace original non-inverter units that were over 10yrs old. Was able to get bigger BTU for same physical condenser size (compressor units a bit bigger though). Therefore the replacements inside fitted perfectly where the old ones had been. Upshot is that the extra capacity can cool the rooms faster and (by my thinking) is less taxing on the units. Therefore longer life perhaps? Either way the new units are much, much quieter and the energy savings dramatic. My electric bills dropped by about 30-40%. Now I'm thinking about replacing a 13yr old fridge freezer that is non-inverter and gets very hot on the side panel at times. Anyone here have any experience with the Samsung inverter fridge freezers and their efficiency?

 

I bought this one 3 month ago , works fine , anyway when doing his non frost defrosting get warm too , is needed to defrost .

 

Bought because my Toshiba " played dead " ????...., but was not    ???? as a few days later i tried him (i disconnected Toshiba when not cooling anymore ...... but seems he had an overwhelming ice behind the inside back part .... so fooled me , having 2 working fridges now and leaving Thailand in 4 months to go live home country again  ????

 

Anyway the Samsung has sliding 70 cm shelves on wheels and vegetable container also on sliding wheels , perfect fridge and as inverter low consumption , and 5 in 1 possible positions , separate circuits , all specifications what some latest Samsung inverter fridges can ..... it is all listed  in the attached  PDF, making one big fridge , or 1 small fridge out of the freezer , holiday mode , etc

 

If go buy  lotus or Big C   check several days different as those fridge prices change up and down  by day , just like the airlines ???? ..., Samsung  was 500 cheaper than when i bought few day before that Hisense i returned .....so be aware when buying !!

 

Had first bought a Hisense ..... but changed it to this one by Lotus , as  Hisense cooling not accurate i found 

 

SAMSUNG Normal price RT43K6230S8_ST 15.6Q.pdf

Edited March 19, 2022 by david555

[sometimewoodworker]

2 hours ago, david555 said:

But they are more expensive buying

Proof please. That used to be correct, it isn’t now.

 

2 hours ago, david555 said:

consider cheap Thai elec.

Thai electricity is only cheap if you are a very low user, otherwise it certainly is not cheap.

2 hours ago, david555 said:

and the electronics more touchy

Apocryphal, please provide proof of that statement.

 

Possibly in the early days it was true, today, proof please.

 

2 hours ago, david555 said:

in case of repairs more expensive they told to me

And the cost of a main PCB for both kinds is?

[Crossy]

2 hours ago, david555 said:

But they are more expensive buying (consider cheap Thai elec.) and the electronics more touchy , so in case of repairs more expensive they told to me.....so as always pro's and con's....????

 

Prices are rapidly approaching parity with non-inverter types, as is the cost of repair and the works are significantly more robust than in the past.

 

Ask me 5 years ago and I would think twice about an inverter, now I would only consider an inverter.

 

The manufacturers really love making inverter A/C units:-

• Once the development costs are recovered the electronics is cheap.
• The electronics allows them to use much cheaper motors (they can be designed right to the line as the smart bit protects the motor).
• They do actually save energy so they have a built in selling point for the masses.

So, they have a product that's less costly for them to make that they can (could) sell at a premium, or at least the same price as a conventional unit that costs more to make and the public actually wants the new product.

 

One of those rare occasions where everybody wins, including the environment!

[david555]

1 hour ago, sometimewoodworker said:

Proof please. That used to be correct, it isn’t now.

 

Thai electricity is only cheap if you are a very low user, otherwise it certainly is not cheap.

Apocryphal, please provide proof of that statement.

 

Possibly in the early days it was true, today, proof please.

 

And the cost of a main PCB for both kinds is?

could be they are now more common , and so almost same price , but i can only compare with what i experienced in price difference  when buying my A.C Panasonic non inverter who served me until now without problems for more than 10 years ....

 

Not tearing down your inverter love ....???????? no more comparing info  for me as my oldie system keeps working fine ....., probably  my eventual next one would be inverter as no other ones could become available......,

 

but 10 years ago i could have many Thai Kwh. for the difference in price  at that moment 

 

About Thai electric price i pay 428,35 Thb for 111 units direct from PEA so 3,86 Thbt a unit ,......no middle man / woman  involved jacking up the money for his / her pocket ????

[soi3eddie]

3 hours ago, david555 said:

I bought this one 3 month ago , works fine , anyway when doing his non frost defrosting get warm too , is needed to defrost .

 

Bought because my Toshiba " played dead " ????...., but was not    ???? as a few days later i tried him (i disconnected Toshiba when not cooling anymore ...... but seems he had an overwhelming ice behind the inside back part .... so fooled me , having 2 working fridges now and leaving Thailand in 4 months to go live home country again  ????

 

Anyway the Samsung has sliding 70 cm shelves on wheels and vegetable container also on sliding wheels , perfect fridge and as inverter low consumption , and 5 in 1 possible positions , separate circuits , all specifications what some latest Samsung inverter fridges can ..... it is all listed  in the attached  PDF, making one big fridge , or 1 small fridge out of the freezer , holiday mode , etc

 

If go buy  lotus or Big C   check several days different as those fridge prices change up and down  by day , just like the airlines ???? ..., Samsung  was 500 cheaper than when i bought few day before that Hisense i returned .....so be aware when buying !!

 

Had first bought a Hisense ..... but changed it to this one by Lotus , as  Hisense cooling not accurate i found 

 

SAMSUNG Normal price RT43K6230S8_ST 15.6Q.pdf 569.06 kB · 1 download

Thanks. That's exactly what I'm looking for and similar in size to my old Toshiba. Suppose it's too early to say if there's any energy saving. 

 

[Crossy]

5 minutes ago, david555 said:

but 10 years ago i could have many Thai Kwh. for the difference in price  at that moment 

 

But, we are not talking about 10 years ago are we???

 

What was the correct decision then (it likely was) may be not be the correct one now (it probably isn't).

 

If your current units are functioning OK and your bills are not excessive why change anything?

 

[david555]

Just now, soi3eddie said:

Thanks. That's exactly what I'm looking for and similar in size to my old Toshiba. Suppose it's too early to say if there's any energy saving. 

 

i guess there is...., as my consumption is only 111 units  now at  this season , cooking .....,light ..,big Sharp fan almost a 20 hours a day on  whole day time and evening big Television ( 49 inch ) which i also use as computers screen  , as with this corona time i am almost whole days home ...

Hot season is more as then AC in use