Response from Rosa:
.... Thank you very much for your compliments and gratitude. I am happy that you enjoyed your stay in my apartment.
Regarding the issue of hot water in the shower, I would like to comment that few days ago, just before your stay, I installed a new hot water tank for heating water.
Thanks to your information, I noticed that it needs an accurate adjustment.
It has been tested and adjusted again, and now the tank works as expected, providing water for a shower of 12 minutes. Then you have to wait about a quarter of an hour to provide 12 minutes more of hot water.
I have ordered a new apparatus from an American technology firm that will provide endless hot water. It consists of a complementary device that will be connected to the existing water tank. It is based on graphite electrodes. In few days it will be installed in my apartment.