Air con experts

[KannikaP]

Good morning experts. I have two 12 year old Mitsu 12000 Mr Slim, on/off air cons in my 36 sq mtr lounge, 3 metres apart on the outside wall.

Last month I bought a TLC Inverter 12000 from Lazada as it was a very good price, Bht 7500, including delivery. My local man came on Sunday and charged me Bht 3000 to remove one of the old ones and fit the TLC.

I decided to compare the efficiency/power usage between the two. I have a ‘smart’ thingy in my fuse box (CU) which sends the electricity consumption to my phone. I turned everything off on the breakers and tested each air con individually setting each at 28C, normal cooling for 20 minutes and recorded the number of units used. Then I did it with the Economy button pressed. Here are my results.

 

TCL. Normal = 0.50 units, Eco = 0.35, which equates to 1.5 and 1.0 per hour.

Mitsu. Normal = 0.34 units, Eco = 0.28 per hour, 1.0 and 0.72 per hour.

So the old one seems to use less electricity than the new TLC over the period of one hour. WHY?

 

Also, I wonder exactly how the units work. I know from testing myself that they both pump out cool air at 17-18C. They drawn in air from the room into the top, through the exchanger and back out into the room, until the temperature sensor measures that the air going in is at the temperature you have set on the remote. Then it turns off, or slows down, until that rises, then it turns back on. If you want the room to be cooler, it simply takes longer for the cool air to mix with the room’s air until the desired temperature is reached. The outside temperature is irrelevant, only that the room can get hotter if insulation, windows, curtains etc are not considered and allow the room to heat up.

Can someone explain IN SIMPLE TERMS, no scientific formulae please? Thank you.

I am considering another TLC as they are on offer on Lazada tonight, 10/10. But if the difference in the cost of running the old one is the same or less than the TLC, which will cost me about Bht 11k including fitting, what will be my return on cost per year? OK, a warranty on the TLC, one year on the TLC card, 5 years on Lazada????

 

[JBChiangRai]

Inverter units save money in normal usage by adjusting the compressor speed and rarely if ever, starting up from stationary.

 

Your test isn't comparing like with like.  You need to get the room to the temperature you like, then compare the costs of maintaining at that over an hour and similar times of day/outside temperature.

 

I think the refrigerant gas can make a difference too, old units may use gas that has been outlawed on new units.

 

You could compare EER ratings too.

[KannikaP]

My test is EXACTLY comparing like with like, two aircons in the same room at more or less the same time, so room temperature is similar. The outside temperature is irrelevant as I explained.

OK, the Mitsu has R31 and the TLC has R32 refrigerant.

EER and SEER ratings mean nothing to me if I have proved that the electricity consumption is greater for one than the other. That's really what matters.

I shall repeat my tests over an hour as opposed to 20 minutes and see the difference then. Thanks for replying.

[chickenslegs]

1 minute ago, KannikaP said:

My test is EXACTLY comparing like with like, two aircons in the same room at more or less the same time, so room temperature is similar. The outside temperature is irrelevant as I explained.

OK, the Mitsu has R31 and the TLC has R32 refrigerant.

EER and SEER ratings mean nothing to me if I have proved that the electricity consumption is greeter for one than the other. That's really what matters.

I shall repeat my tests over an hour as opposed to 20 minutes and see the difference then. Thanks for replying.

I'm not an expert, or even close, but I have a couple of comments.

1. AFAIK it's the frequent restarts of the older unit that consumes the most power. So I think you will get better results over a longer period, say overnight.

2. Using 2 units in one room at the same time. How can you know which unit was more/less responsible for the drop in temperature. Is it possible that the new unit was working harder to get down to the set temperature? 

[KannikaP]

9 minutes ago, chickenslegs said:

I'm not an expert, or even close, but I have a couple of comments.

1. AFAIK it's the frequent restarts of the older unit that consumes the most power. So I think you will get better results over a longer period, say overnight.

2. Using 2 units in one room at the same time. How can you know which unit was more/less responsible for the drop in temperature. Is it possible that the new unit was working harder to get down to the set temperature? 

I look at my power metre on my phone, and do not see a great boost in use on restarts.

I do the tests on the air cons individually so I know how much each has taken during the same length of time. The TCL seems to be taking 1500 watts whereas the Mitsu is around 1000.

But as I said in my previous post, I shall try over an hour instead of 20 minutes.

I do not use my a/cs overnight, bedroom 7 to 10 pm @ 28C, lounge about 4 hours each afternoon also at 28@.

[JBChiangRai]

It helps if you understand the ECO mode.

 

On your Mitsu, it cannot slow down the compressor, what often happens on these type of units is ECO mode sets the temperature to 1 or 2 degrees higher than what it displays. You select 28C and it will deliver 30C.

 

On an Inverter unit, it does something with the compressor.  I'm not sure what, I've tried to research it on TCL units several times and I'm still not sure. I think it prevents the compressor from running at full speed.

 

28C on both units will get the room to different temperatures.  On your Mitsu you will get hysteresis of about 2C so the room will cool to 27C and then wait till the room hits 29C before restarting.

 

On an inverter the temperature control is much finer, often within 0.5C which is why they are recommended for bedrooms.

 

I don't think you can compare them very easily.  Additionally, on an Inverter model, setting it to whisper mode will reduce the available cooling to prevent evaporator icing.

 

Ideally, test over the same period, preferably a whole day and again on a similar day.

 

 

[JBChiangRai]

15 minutes ago, KannikaP said:

I look at my power metre on my phone, and do not see a great boost in use on restarts.

 

 

You won't see it as it's typically a second or less, and typically 3-5 times the steady state.

[KannikaP]

10 minutes ago, JBChiangRai said:

 

You won't see it as it's typically a second or less, and typically 3-5 times the steady state.

So ONE SECOND at 3 or 5 kW every 30 minutes or so, will not drastically increase my power consumption, no?

[Schoggibueb]

I'm not an expert either, just a few thoughts about your topic and my very personal oppinion...

- As alreday mentioned above, 1hour running time isn't enough. Make your test for 24 hours. Seperatly, same conditions.

- Are both compressors outside shaded the same way? If you can choose a location for the compressor, try to place it on a shady place insted of having it standing in the sun. Makes a difference in power consumption.

- Your display on your mobile cant catch the peaks when a compressor starts. Newer compressors could maybe run / be controlled by frequency modulation, but I'm not sure if this is used for AC's.

-

[JBChiangRai]

2 minutes ago, KannikaP said:

So ONE SECOND at 3 or 5 kW will not drastically increase my power consumption, no?

 

Over the course of a few hours, a dozen or more times per hour, it will make a difference.

 

For me, it's not about the power, it's about the comfort.  I like my air con silent, you can't do that with a legacy system because it can ice up as the compressor can't slow down.

 

I do mean silent, I don't mean quiet.

[chickenslegs]

I just looked again at the labels in the OP.

 

The TLC is rated 1 star for energy efficiency but the older Mitsu is rated 5 stars. That seems like a huge difference.

 

[KannikaP]

11 minutes ago, chickenslegs said:

I just looked again at the labels in the OP.

 

The TLC is rated 1 star for energy efficiency but the older Mitsu is rated 5 stars. That seems like a huge difference.

 

That's what I though, hence posting them.

[KannikaP]

37 minutes ago, JBChiangRai said:

For me, it's not about the power, it's about the comfort.  I like my air con silent, you can't do that with a legacy system because it can ice up as the compressor can't slow down.

 

I do mean silent, I don't mean quiet.

Both TLC and old Mitsu are about the same quietness. 

I put the TLC on for over an hour, it's only just been fitted, and yes, it started at 1500 watts and is now down to 750 ish. The Mitsu stays at 1000. So over a year, it will make quite a difference.

I thank you, and Chicken Legs and others who replied with your valuable knowledge, and yes, I shall buy another TLC on offer at Lazada at 20.01pm tonight. I have all the necessary vouchers in my account, so 7250 it is. Great.

Is 3000 for fitting a rip-off? The holes are already in the walls. The bracket is there for the outside unit.

For Schoogibueb, yes the compressors are fairly well shaded from the afternoon sun. 

[KannikaP]

58 minutes ago, JBChiangRai said:

I do mean silent, I don't mean quiet.

If a fan is turning and blowing air, there is no way it can be SILENT, very quiet yes, but not silent.

My Mitsu's noise has never bothered me in the bedroom, as has the Mrs' snoring. Neither the a/c or the Mrs have ever iced up. I get them cleaned every 6 months.

[scubascuba3]

41 minutes ago, chickenslegs said:

I just looked again at the labels in the OP.

 

The TLC is rated 1 star for energy efficiency but the older Mitsu is rated 5 stars. That seems like a huge difference.

 

You aren't reading it correctly, it's not 1* but 5*

 

Here's mine

[JBChiangRai]

2 minutes ago, KannikaP said:

If a fan is turning and blowing air, there is no way it can be SILENT, very quiet yes, but not silent.

My Mitsu's noise has never bothered me in the bedroom, as has the Mrs' snoring. Nither the a/c or the Mrs have ever iced up. I get them cleaned every 6 months.

 

I have Mitsu's as well as TCL. 

 

The TCL is as near damn silent as you can get. 2m from it, I defy anyone to tell me whether or not it is running on silent setting.

 

Mitsubishi Inverter units post a decibel reading for their A/C's, on the silent sitting you will see they don't give a reading, it's unmeasurable.  

 

I notice you get the Mrs and the A/C cleaned every 6 months, unusual, but each to their own, I'm interested how you clean her every 6 months?

[KannikaP]

8 minutes ago, scubascuba3 said:

You aren't reading it correctly, it's not 1* but 5*

 

Here's mine

Yours does not show any star rating, mine has a green colour on No. 5/1. Mitsu shows 5/5.

SEER is 18.7 so that's good, so I read.

[KannikaP]

52 minutes ago, chickenslegs said:

I just looked again at the labels in the OP.

 

The TLC is rated 1 star for energy efficiency but the older Mitsu is rated 5 stars. That seems like a huge difference.

 

I find No. 5, electricity cost per year to be rather silly. Surely it depends on how long and often you use it, and how much you pay per unit of lekky.

[JBChiangRai]

6 minutes ago, KannikaP said:

Yours does not show any star rating, mine has a green colour on No. 5/1. Mitsu shows 5/5.

SEER is 18.7 so that's good, so I read.

 

The Star rating IIRC isn't based on efficiency but on absolute power draw.

 

(edit: I might be wrong on this, it looks like it's changed from when I last looked when it used to just be a number).

[KannikaP]

9 minutes ago, JBChiangRai said:

 

The Star rating IIRC isn't based on efficiency but on absolute power draw.

It says consumption PER YEAR. Yours being 18k BTH says 15054, mine being 12k says 9634. For me that is 803 units per month or 27 per day.

That means over 1 kW per hour, 24 hours a day.

Summat ain't quite right in their maths.

 

 

[OneMoreFarang]

What makes non-inverter ACs ineffective is that they switch on and off. Every time they switch on there is a big load.

Your meter may be able to read this correctly or maybe not.

 

(I am pretty sure) Inverter ACs don't work all exactly in the same way. The electronic tells them what to do in detail, and electronics are different in different models.

 

Just a sample: My brand new, top of the line, Daikin ACs need about a minute after I use the on button to actually blow cold air. Maybe they start the inverter very slowly (to save energy), or maybe the set some other elements like the direction fins first in the desired positions, there might be many reasons.

 

Personally, I wouldn't expect much of a cheap Noname device. 

[KannikaP]

11 minutes ago, OneMoreFarang said:

Personally, I wouldn't expect much of a cheap Noname device. 

TCL = NoName device? Which also takes a short time to start the cold air after switch on.  Unfortunatley my fins only move up & down, not left & right as well. Ah well, you get what you pay for! 

[KannikaP]

34 minutes ago, JBChiangRai said:

The TCL is as near damn silent as you can get. 2m from it, I defy anyone to tell me whether or not it is running on silent setting.

Where is the SILENT setting please. Or maybe my cheapo model does not have.

[JBChiangRai]

1 minute ago, KannikaP said:

Where is the SILENT setting please. Or maybe my cheapo model does not have.

7 minutes ago, OneMoreFarang said:

What makes non-inverter ACs ineffective is that they switch on and off. Every time they switch on there is a big load.

Your meter may be able to read this correctly or maybe not.

 

(I am pretty sure) Inverter ACs don't work all exactly in the same way. The electronic tells them what to do in detail, and electronics are different in different models.

 

Just a sample: My brand new, top of the line, Daikin ACs need about a minute after I use the on button to actually blow cold air. Maybe they start the inverter very slowly (to save energy), or maybe the set some other elements like the direction fins first in the desired positions, there might be many reasons.

 

Personally, I wouldn't expect much of a cheap Noname device. 

 

On my units, if you cycle through the fan speeds, you will get a loudspeaker symbol struck out diagonally, like a mute symbol.  Mine doesn't have a button for it, but it appears before you get to the first bar for slow speed.

 

4 minutes ago, KannikaP said:

TCL = NoName device?

 

According to Lazada, TCL is the market leader in Thailand.

 

Daikin & Mitsubishi don't come close to them for VFM combined with reliability.  There has been a quiet revolution in Thailand over the last 4-5 years with aircons.  The Chinese have come in and taken market leading position.  We're seeing something similar with EV's, BYD is now the third largest automaker in Thailand by sales volume and will probably be second only to Toyota soon.

[KannikaP]

3 minutes ago, JBChiangRai said:

On my units, if you cycle through the fan speeds, you will get a loudspeaker symbol struck out diagonally, like a mute symbol.  Mine doesn't have a button for it, but it appears before you get to the first bar for slow speed.

Thanks for that. It seems it is just a VERY slow speed fan, but is OK for my personal use.

Shame it doesn't say that in the manual, or does it? Shall have another butcher's.

[scubascuba3]

19 minutes ago, KannikaP said:

TCL = NoName device? Which also takes a short time to start the cold air after switch on.  Unfortunatley my fins only move up & down, not left & right as well. Ah well, you get what you pay for! 

the fan fins can move left and right

[KannikaP]

7 minutes ago, scubascuba3 said:

the fan fins can move left and right

Not on my model. Only up & down.

[Fruit Trader]

1 hour ago, KannikaP said:

Is 3000 for fitting a rip-off? The holes are already in the walls. The bracket is there for the outside unit.

 

Is a little over priced considering brackets power supply and trunking are already installed. Removal of the old AC is easy, gas recovery into the outdoor unit takes leas than a minute.

 

Note. As scrap, a fully copper AC will place up to 1600-1800 Baht in your installers pocket, aluminium about 700-900 Baht.

 

The best way to test your AC's in the same room is let each come up to set point then monitor cost to hold temperature over time. Important to measure room temperature with separate device because accuracy of AC's setting varies between brand.   

[scubascuba3]

34 minutes ago, KannikaP said:

Not on my model. Only up & down.

move manually to angle left or right

[Yellowtail]

First, if an air conditioner is undersized or even sized correctly, you will not realize significant savings with an inverter. 

 

When both units are running "wide open", the power consumption should be similar. Undersized units run "wide-open" most of the time, so the start-stop vs cycle-down is not much of an issue. 

 

I would guess your return-air temperature on the mitsu is reading higher that the TLC, so it is actually making the air cooler than the TLC.

 

The outside temperature is significant, because the hotter it is, the harder the condenser (outside unit) has to work. 

 

The compressor in the condenser uses most of the power. The evaporator (inside unit) is mostly just a fan box.