The air conditioner for the summer works well for a space of 40 square meters and cools effectively. However, when you switch to heating with an outside temperature of 15 degrees and 20 inside, if you set it to 22, it goes to 24-25 by itself in 3-5 minutes on the second/third speed setting, then it turns off and doesn’t turn back on for a long time unless you raise it by 1-3 degrees as indicated by the unit (it will turn on for a little while) and then it does the same again. But if you set it to 28 or 30 when the unit's temperature is 23, it will run for a long time and turn off at 31-32 degrees (I saw this crazy thing) for a few minutes and then turn back on. In short, the degrees on the unit have nothing to do with the actual room temperature, they change like crazy in seconds, it is assumed that the thermostat has an issue otherwise it cannot be explained. It doesn’t emit strong warm air, while in cooling mode it emits quite a bit. The outdoor unit is very noisy in turbo mode, which we say doesn’t make much noise, so it has a problem. Not all functions work correctly in the app (for example, you set it to blow vertically and it doesn’t work, and only if you press for eco does it change to vertical and the eco doesn’t work, or if you want to change the air direction horizontally/sideways it also doesn’t work, and so on). The job can only be done via remote control. Conclusion: You contact the dealer, send a video, and the thermostat is replaced along with the outdoor unit. For the app, from inside Google Play, you will see comments that are similar to your issue, you send a message to the address provided by the administrator who responds to tell you what to do to fix the problem. That’s it, guys, it’s just a hassle.

Positives:
Affordable to buy, lightweight/easy to install, construction materials seem good (no creaking, etc.), noise from the indoor unit is from zero to not bothersome and has a good design, has wifi/ionizer for this price, 5 years warranty and Eurovent certification.

Neutrals:
The app does not have all the functions nor does the remote control, so you have to use both. The various functions, of course, have almost zero difference in consumption and minimal in behavior.

Negatives:
The outdoor unit is noisy especially at low speeds/watts and very noisy when transitioning from high loads to lower ones and stays there (which it should when reaching temperature) with a continuous loud hum from the compressor; at night it will definitely be bothersome if close to a window. At higher loads, the noise is significantly less to minimal... all of this is probably irrelevant if the unit is placed on the floor.
Consumption, the compressor probably has 3 to 4 speeds and does not seem capable of dropping below 380-400 watts consumption at low, below that it simply shuts off, so the "seer 6.1" is clearly a lie for conditions in Central/Southern Greece; the maximum I have seen it reach for a short time is 1120W in turbo (it calls it rapid) for 1-2 minutes.

All of this for cooling, for the 12, measured after 20 days of use in July/August with tapo p110 in a space with medium/poor insulation and a slab above ~15sqm; for better insulated spaces it should be okay but there are countless parameters at play.
I wouldn't say it's a bad purchase; you definitely don't regret your money, but with installation costs of €80-120, you approach €500; if you can find something better with free installation, do it especially if it’s going to operate for MANY hours.

The 12,000 BTU air conditioner was installed in a dining room of approximately 25 square meters, built in 1972 and facing north. It was purchased through Skroutz for €338 (in July 2022). During the heatwave, it worked perfectly day and night, set at 26-27°C, and lowered the temperature to 25°C and the humidity to 48% from 33°C and humidity above 65% in about half an hour. The wifi connected to the hOn app by Haier in seconds, and I operate it from my mobile phone. I have reservations about the quality and durability of the plastic parts in the indoor and outdoor units. I am the owner of two old non-inverter Fujitsu air conditioners, 9,000 and 24,000 BTU, which have been working flawlessly for 24 years, and the difference in weight and quality of the metal and plastic parts is more than evident, but this applies to all new machines. The positives are that it is quiet, the remote control has colorful buttons, and it can be operated and programmed from the mobile phone via WiFi. Additionally, it comes with a 5-year warranty from Inventor via email. I also installed a 12,000 BTU Pearl from the same company in the bedroom, and the only noticeable difference is that the Pearl has a more matte plastic finish. I note that the Pearl was also purchased for €338 through Skroutz (in July 2022), and then the price skyrocketed. Update 07/2023: After 1 year of operation, I changed my rating to 5 stars because the heating function works flawlessly and the App's operation via WiFi has been very helpful. It is wonderful to be able to activate the air conditioner remotely and arrive home to the right temperature. It offers great value for the price I purchased it for.

Well, the house was built in 2005 with simple aluminum windows and energy class C! (Very important) 12,000 BTU for €330 permanently at 22 degrees in the living room of 30m2. It went from 24 to 21! Now, in strong bad weather, it defrosted once for exactly 15 minutes and we didn't notice because it reached 21 degrees! If the house has losses, you need a more powerful air conditioner! I measured consumption and it was from 1.5 kWh to 1.8 kWh per day with a lower temperature of -2 in Athens! I want to emphasize that if the house has losses, as soon as you turn on the heating, the temperature drops rapidly and consumption increases! I recommend you to energetically upgrade your house with insulation (as it is my job) and you will recover the money in a maximum of 3 years from electricity, oil, natural gas, etc.! Be careful if you only insulate the walls and have losses from the ceiling (terrace). The only thing you will do is trap the cold air that goes downwards and you will not have the desired results (the solution is internal insulation on the ceiling if it is not feasible from above). You can combine it with a thermos or Styrofoam refrigerator, whatever you put in it will keep it for a longer period of time! Finally, the application is perfect, I create scenarios, for example, at 2:30 pm to open it so that it is warm when the child comes home from school at 3:00 pm! It doesn't get stuck anywhere and it has served me very well! PS: There is also an annual energy saving program for those who say they don't have money for energy upgrades in their homes! I hope I helped

23/12/2021:
The review concerns the 12,000 BTU unit with 15 days of operation:
Two similar units were installed in a single-family house in two different rooms of approximately 16 sqm each, but with doors and windows, without insulation. I made the change for economic reasons from two non-inverter General Electric units from the 20-year period. The air distribution is very good and can easily be compared to the Fujitsu units I have installed in two other rooms of the house. I have not used the Wi-Fi. It is very practical that when you turn it on, you can also see the temperature of the room and the outdoor temperature, and adjust accordingly. On the inventor's website, you enter the serial numbers and immediately receive a letter with a written 5-year warranty. I will come back for consumption and any issues. The first impression is very positive.
26/12/2022
After one year of use, I can say that this air conditioner is an excellent choice. It performs well in both heating and cooling. Highly recommended!
26/06/2024
After winters and summers, I highly recommend them. True inverter operation.

It was installed on 8/21 as a replacement for a Fujitsu 24,000 BTU model from 2003 in a 55 sqm space. I made the change for economic reasons because the Fujitsu was not an inverter. I had many doubts if I did the right thing because I didn't have a problem except when the temperature dropped below 4 degrees, the Fujitsu didn't perform well, as stated in the prospectus. Impressions after the first cold days: (for cooling, there's nothing to say, we froze!) Absolutely amazing! We feel like we changed houses, like we have a radiator and not an air conditioner, because the air distribution reaches every corner of the space. Honestly, I don't have words to describe it better. With the Fujitsu, you would get warm enough where the blinds hit, and if you changed the sofa, you would freeze! The Wi-Fi is also fantastic and very easy to use. You can turn it on from your phone not only to warm up the house, but also to see the temperature inside and outside, and adjust accordingly. Exemplary company, I entered the serial numbers on their website the same day of purchase, and they sent me the written 5-year warranty without any conditions in seconds! The air conditioner is the only source of heat, and I am completely satisfied with everything. It's quiet inside and outside without any plastic noises. The remote control menu is easy to use and the prospectus is explanatory. The only negative thing, let's say, is that it doesn't have an independent fan function like the Fujitsu, which is very practical at the beginning of summer. I'm waiting to see its performance in extreme cold and especially at temperatures around zero, and I will come back to share my experience.
Continuing today, 24/11/2021: with the temperature outside at 10-14 degrees and high humidity at 70-80%, I have it set at 21 degrees on the low setting and the house is warm without humidity! The outdoor unit releases water buckets, so it draws moisture from the space and dries it. At some point, the Wi-Fi app showed as deactivated and I couldn't fix it. I contacted Haier Europe support via email, and they replied that I would need to unplug the router and the air conditioner from the socket and then plug them back in after 5 minutes. I did exactly that and it worked. The ONLY fan function that I mentioned earlier and is not available on the remote control, is available on the phone app! The temperatures displayed on the phone and on the air conditioner's display are very accurate with the environment, I checked them with a thermometer. I will come back with more information during extreme cold weather.
Returning on Monday, 20/12/21, immediately after the Carmel storm. External temperatures for 3 days ranged from 2 to 8 degrees, and the indoor temperature was constantly 22 degrees. The fan was on full power, and the warm air was perfectly distributed without any issues. Yesterday, on Sunday, when we were constantly at home, the unit only stopped for half a minute for defrosting! No noise, no interruptions. I am waiting for the next extreme cold weather with temperatures below zero and will update.
And now we have reached the challenging part... Update now on Monday, 24/1/2022, at 20:30 with the "Elpis" storm. The external temperature is 1 degree. The indoor unit is set to 20 degrees. It manages to maintain the temperature in the living room between 15-17 degrees and constantly defrosts the compressor outside. It doesn't manage to perform as advertised, working up to -15 degrees. The only solution is to have a heater in the room to assist it.
UPDATE: during the "Varvara" storm on 5/2/2023, with external temperatures ranging from 0 to 3 degrees, I set it to 28 degrees indoors, and the unit was running non-stop! It defrosted for 10 minutes every 8 hours, while when I had it at 20, it defrosted every 20 minutes! I note that the house is an old one from 1970 without any insulation, wooden shutters, a terrace on top, and no other houses around, like a reed in the field, meaning it gets hit by all the winds. I have bought a 12,000 BTU DAIKIN for the bedroom and a 9,000 BTU MITSUBISHI for another room. The HAIER worked better than all of them, it produced the warmest air, and its outdoor unit faces the north, Mount Parnitha, while the others are protected. Conclusion: IN COLD weather and in old houses without insulation and aluminum, you need a larger BTU capacity and an increase in the indoor temperature.