The air conditioner has a major issue, which I also read about in another review. It sometimes fails to detect the room temperature and adjust the fan speed accordingly. Additionally, its power consumption is not likely to be A+++.
The manufacturer states that the power consumption for cooling is 640W (240～1380), which I can confirm. It starts working at 800W-1000W and ends up at 400+W once the room reaches 23 degrees and I have set it to 27 degrees at 5 in the morning. As you can understand, it becomes a blanket at night. Alternatively, you can set it to open and close multiple times during the night through the application, in a specific mode, temperature, and airflow.
Lastly, it is relatively quiet. If you put the fan on auto, which you would expect to reduce the airflow when it reaches the desired temperature, it does so at some point and it had a relative noise. It also has a fan mode called mute or silent, where both the noise and power consumption are reduced.
The disappointing thing is that in a small room of 12 square meters, it should work better and more economically with the auto mode rather than the mute mode.
And since I haven't mentioned the performance anywhere, yes, obviously it does the job, it cools the room quite well. I don't have a particular opinion on its heating function.

Review for 18K BTU.
Purchase on 23/12/2022. Installation on 24/12/2022.
The air conditioner was recommended by the technician who installed it. I must admit that I was skeptical due to the company's lack of knowledge.

1. First, let's talk about the installation. It must have at least 2 meters of piping in order for the air conditioner to perform as it claims. Unfortunately, most technicians only use 1.5 meters, resulting in the air conditioner not delivering what it promises.
2. 10-year warranty from Tournikiotis Group. This says a lot about their support and future spare parts availability.
3. It has been working non-stop, day and night, with the temperature set at 22 degrees (heating). Its energy consumption is minimal for the atmosphere it creates in the house. In a week of continuous use, it hasn't consumed more than 70kw (until it reaches the desired temperature, it was running at full power). I have a meter on the socket.
4. We can't even tell that it's working. We haven't heard any plastic parts creaking so far, nor have we heard any noise from the indoor and outdoor units.

What I understood is that the installation of each air conditioner is crucial for its smooth operation. Those who buy an air conditioner should ask for the two pipes that are included in the price anyway. You've already paid for them, guys. For some reason, the manufacturer provides at least these measurements. And even if the indoor and outdoor units are next to each other, make sure to spiral the pipe behind the outdoor unit. Nothing is visible.

In conclusion, I highly recommend it based on the current data. If anything changes, I will update my review.

I bought 2 of the 9000 btu units for heating in two northern bedrooms. The positives are that it has quiet units and has a sleep mode that reduces the noise significantly. The children who sleep in the rooms have never complained about any disturbances. However, I can hear a slight continuous sound and some people may not like it.

As for the WIFI settings, it is really easy to connect. I didn't expect it. And the app is very user-friendly, you have full control from anywhere with your mobile phone. I have programmed it to maintain the desired temperature according to the time. It's very convenient because the children don't know how to operate it.

It performs very well in heating. We started using them in early October and will close them in May (here in the north). Even with temperatures dropping to zero outside, the ACs kept the rooms at the desired temperature. I'm looking forward to seeing how they perform in January when we will have negative temperatures. But I'm already sure they will manage it. Incredible performance.

The only mistake of the distributor is that they advertise it as A+++. It's very wrong because it ruins the very good comments we give here, those of us who bought them. It's not at all in that class. When temperatures drop below 7 degrees and with northerly winds, it gets loud. I would say it's an A+ which is very okay for its price.

During installation, I insisted on using a pipe length of at least 1.5 meters and a vacuum pump, and the units were perfectly aligned and not against the north as the experts request.

I haven't tried the self-cleaning function yet to tell you what it does. Generally, I believe in taking out the filters and washing them by hand with warm water.

Update 14/2/2023: The TCL unit gives its all at -3 degrees. I set it to 18C and it actually maintains it within the range of 17-19C. The noise from the motor at night under such conditions is now noticeable and expected.

And the 56 stores that sell it on the Skroutz platform do not have any photos of the external unit and the dimensions they mention and obviously copied from the representative which, however, are much larger than the ones that came with my machine. Today it was installed, of course, I am very skeptical about whether its performance will be as the manufacturer claims because, as I mentioned before, the external unit is quite smaller especially in its depth and length. It is worth noting that internally the external unit has a condenser next to it for those who do not know what a condenser is, it is a refrigerator container of the external unit to cool the refrigerant when it passes through it, something that more expensive machines have to reduce consumption and obviously for this reason it made the unit smaller. I have the relevant photo posted showing the double condenser. I hope its features correspond to reality. I don't give it five stars, it may deserve them, but because the representative does not provide a photo of the external unit and gives wrong dimensions, it is not allowed for a serious company to make such mistakes. It is the well-known representative who also imports Mitsubishi. The internal unit has dimensions of 810 length, 300 height, and 210 depth, and the external unit has a length of 730, height of 540, and depth of 260, while on the site and in all stores they mention a length of 795, height of 549, and depth of 305 millimeters. Today, September 10th, 2022, I installed a second 12,000 BTU air conditioner. For this, I had to use the WiFi, it connects easily, very good application, you need to download the application from Google Play, open location on your mobile and Bluetooth, and have WiFi or data. You go to device search for TCL air conditioner, it has an image, you open the air conditioner in cooling mode to work and press the middle button on the remote control six times, continue to the second phase and it responds with two beeps, asks you to enter the router password, and everything is okay. I was impressed by how easy it is compared to Mitsubishi, which asked me to enter all the codes separately for the external and internal units, the barcodes, very time-consuming, we had to send you identification codes from the center, a woman opens e-banking at the meeting. Here things are very simple with TCL. The Wi-Fi mechanism is on the top right of the internal unit when you open the lid to clean the filters, it appears the size of a matchbox, and just for that, we change the rating to five stars from four.

Anti-vibration Floor Stand for Air Conditioner - https://www.skroutz.gr/short_videos/1477/thoryvodis-exoteriki-monada-klimatistikou-yparchei-lysi

Self-cleaning program of TCL Miracle II air conditioner - https://www.skroutz.gr/short_videos/1475/programma-aytokatharismou-tou-klimatistikou-tcl-miracle-ii

Defrosting in TCL Miracle II air conditioner - https://www.skroutz.gr/short_videos/1472/apopsyxi-sto-klimatistiko-tcl-miracle-ii

Regarding the 12000 btu miracle 2 that we purchased in November 2021.

Currently only using it for heating.

After the purchase and installation, we noticed a sound coming from the outdoor unit, which created a strong acoustic resonance inside the house. We informed the store, they sent their service, they added anti-vibration pads to the base without touching or opening the outdoor unit (as they should, to avoid voiding the manufacturer's warranty), but the problem was not resolved.

Then we contacted TCL (we had no issues communicating with their service, they always responded, although in our first communication they demanded 40 or 50 euros, I don't remember exactly, in case there was no issue with the unit and we were just imagining it), and they sent a technician relatively quickly. The technician opened the outdoor unit, did what he could to isolate some internal parts to prevent them from vibrating, in order to solve the resonance issue, and asked us to monitor it over time.

While the resonance sound coming from inside the house was reduced, unfortunately, to our surprise, the outdoor unit continued to make a consistently loud noise (you couldn't sit on the balcony because of it). Additionally, many times it made an incredible noise that was not tolerable at all, to the point where we received complaints from neighbors about the disturbance caused, and we couldn't operate the device practically.

After another communication with TCL, they informed us that they would send a technician again to take a look (the second time and a total of three technician visits within a three-month period).

The technician arrived, saw that there was an issue. Today, the outdoor unit was replaced. I will test it for a period of time and will provide an update.

I note that the company's service fully responded, and there was complete coverage.

Update 9/3/22:

The technician came in the previous days, saw that there was an issue. Today, the outdoor unit was replaced. I will test it for a period of time and will provide an update.

I note that the company's service fully responded, and there was complete coverage.

Update: The noise was observed again, possibly even worse than before. I asked if the new outdoor unit was a repaired or new product, but of course, I did not receive an answer. The technician came again immediately, the support and communication with the company are very good. Something was fixed inside the outdoor unit, I will see it over time, as we no longer use heating.

Update 1/7/22: The noise of the outdoor unit is less in cooling mode, obviously because it is under less pressure compared to heating.

However, I must note that the unit performs very well in both heating and cooling. If I didn't have the trouble with the outdoor unit, I would give it a very good rating. I am changing my rating from one star to two stars, due to the unit's performance and the responsiveness of the company's technical department. Also, TCL's mobile application for remote control is very good.

4/2024
I am increasing the rating to 3 stars due to performance, etc

The selection criteria were:
1. 9000BTU
2. Energy class cooling A+++

At first, I had my eye on a Midea with good reviews, but when I finally decided to buy an air conditioner, due to its price and good reviews (I bought it for €399), I preferred to take a little risk and bought this one.
I was pleasantly surprised by the purchase. It replaced an old LG Libero (Very well-made for its time, quiet and good (a rare thing for an LG air conditioner)) with 18 operating levels and a purchase price of €700 (I put it in the adjacent room).
The TCL is just as efficient, even quieter, to the point where you can't tell if the outdoor unit is working. The remote control is simple and user-friendly. I haven't heard the slightest noise that the indoor unit usually makes during cooling. You have the option to reduce the brightness of the display if the light bothers you at night (I do it myself). It also allows you to adjust the louvers for horizontal air distribution.
I'm not interested in Wi-Fi, so I have no opinion on that.
I haven't tested it for heating yet.
It has: Cooling Performance Ratio (SEER) 8.5 W/W
Heating Performance Ratio (SCOP) 4.6 W/W
I will come back in a few months to complete the review. If it doesn't have any problems, the purchase will be an excellent choice.
Update: It also has very good performance in heating. In mine, I don't hear any noise at all. The only negative, for perfectionists, is that when you turn it off and on again, the louvers return to their initial position (like in most units). I mention it because a cheaper one that I gave as a gift to a friend has the ability to reopen with the louvers in the position where you left them (it has memory).