I read many reviews and got confused. So I decided to take the risk and buy it. The machine does what the manufacturer says and does it correctly. If the water input is 15 - 20 degrees, it easily reaches 40 degrees. As the temperature drops, you need to reduce the water flow rate in order for it to have enough time to heat up. It has a special valve that regulates the flow. I followed a hybrid connection, meaning it takes water from the solar panel, so in the winter when the solar panel doesn't heat the water sufficiently, I utilize the lukewarm water without needing to turn on the solar panel's resistance and heat it to the desired temperature of 160 liters, which is the entire tank's water. I use it during the winter in low power mode because the supply cables are thin, and until December, when I have tested it, it's okay. Finally, I would like to advise those who are considering buying it to measure the temperature of the water they will use. If the water is below 15 degrees and you want to raise it to 40 degrees, a single-phase water heater won't do, you need either a three-phase or a gas water heater.

I waited to evaluate it during the winter. Yesterday it reached minus three and part of the water pipe is external, while the rest is underground. The water temperature reached five degrees, but after some flow, it increased to twelve because the pipes are underground. Those that are above ground are at risk of freezing and breaking if the water does not flow a little. When I tried it, the setting was on inverter. It has four settings, and when you install it for the first time, the setting is on the lowest scale, which you need to change unless it is summer. This setting is around 2 kW and it is beneficial to have it during the summer so that you can simultaneously use other devices that consume a lot of electricity. During the winter, however, it requires 5.5 kilowatts and should be set to the third scale, inverter. At first, when the water was frozen, it took a while to raise the temperature. It stayed at 33 degrees out of the 39 I requested, but after a while, when the hot water from the ground arrived, it reached 39 degrees normally. The flow was satisfactory, and I have set it not to run too much to save water. Increasing the flow to full results in a temperature drop to 32 degrees, which is good for winter as I don't need that much water and 32 degrees does not freeze. So, if someone has a problem, they should check their installation because if the temperature is low, it will freeze and the pipe will break. The purchase of the machine cost 80 euros in total from China

It was purchased a year ago, 2 pieces on offer for 120 euros. Let's not forget that they are inverters, so both were installed in a series, one in the bathroom and one in the kitchen with hot water input from the existing solar water heater. I saw savings of 1200 kilowatt-hours in the quarterly bill of 3000. No problem with water pressure, valves have been installed and I have set the maximum flow rate and it works perfectly. Sturdy small construction, fully touch-sensitive and above all Greek. Congratulations to the manufacturers, I am very satisfied.

School editing 14/03/18 1) Many things depend on the water pressure it has. 2) Temperature does not require special valves, the ones that come with the packaging are enough. 3) It is called an inverter because it has temperature reading sensors both at the input and output, so if it drops below 23 degrees Celsius from the hot solar water, the inverter stops the machine and we use the water from the water heater. 4) Greek design and made in China, what can we do about it? Siemens and other companies are also made in China and they cost twice or three times as much and don't offer anything more, the only thing for sure is that whoever wants to buy Siemens or AEG from China will have the same thing with double or triple the money.

It is a product with high build quality, I would say unique for this type of device. Fully electronic and compact, with its functions operated by touch sensitive buttons. It heats water very quickly, however, it does not have good water pressure. Also, in winter the output temperature does not correspond to what it indicates due to the difference in the inlet water temperature compared to summer. I believe that a product of this category, before buying it, you should first try it in a store, to evaluate many things such as the water flow. Both this one and all others from other manufacturers require their own shower head to function properly, which essentially allows a specific amount of water to pass through, increasing the pressure that the device itself has reduced due to its operation. Therefore, be careful in your choice. With the shower head you may already have or some shower column, it does not work properly; however, you can use one with very small holes, specially designed for low water pressure, and make some adjustments, but it will display overheating messages. I believe the water adjustment valve at the inlet has no value, so I removed it. Whether you have high water pressure or not, it reduces it to work satisfactorily.

A big positive is the complete independence from the water heater for the bathroom, since it covers the whole family, no matter how many members there are and whatever time they want to shower. The freedom to use the bathroom, winter or summer, is incredible. Separate from that is the electricity savings.

Edit: I am forced to give it two stars in my rating, however, during the summer months it remains our main device for heating water in the shower. Not only do I use it, but three others in the house whom I must consider. Let me talk about my home's installation: I also have a boiler, which I replaced. For a period in the winter, therefore, I isolated it and used only the boiler, where the whole family noticed the benefits of a boiler and the high water pressure of a conventional "water heater." When we turned off the radiators and went back to the Solcore after two months (we used the boiler's electric resistance in the meantime), there was great disappointment for the obvious reason, the low water pressure. I was forced to find a way not to use its funny shower head, without knowing what long-term cost this will have for the device's life. Nevertheless, its use is positive and I am relatively satisfied. Also, you can get used to its shower head, you just need to spend more time in the shower!!!

It was purchased about 5 months ago. It was installed in the kitchen, in line with the solar water heater, with a flow regulator and bypass (for the summer, when very hot water comes down from the solar heater), while it currently gets power from the dishwasher socket, so I don't use it at maximum power. It works perfectly, has very readable indicators, remembers the settings, and overall "you put it in, set it up, and relax". It has proven to be essential for everyday use at the sink, as you have hot water for rinsing and dishwashing in seconds. Of course, the flow of hot water is small, which I expect to improve significantly when I connect it to a higher power source. Nevertheless, we are very satisfied with the device and regret not buying it earlier. I note that for the bathroom, which unfortunately was far away from the kitchen, I bought the NK1 from the same company (see evaluation there).

Update Aug2018: We have been using it for about one and a half years, now connected to a strong power line (3x6mm2). My initial evaluation still stands, with the following additions: The water flow in winter should be low, even at maximum power, if you want to achieve a satisfactory temperature. For the kitchen and our preferences, this flow is absolutely sufficient, considering that you have hot water in a few seconds. However, I believe that it would not be sufficient for the bathroom under any circumstances.

Having now the experience of using the larger NK1 device in the bathroom, I would choose it for the kitchen as well, despite its higher price. Both the F1D and NK1 are worth their money and the additional expenses and effort for their installation.