When we chose a water heater, we consulted with the specialists https://chosenrooter.com/services/residential/water-heater/ who installed it. As a result, we decided that on the first floor there would be a boiler for one hundred liters, and on the second - for fifty. On the first floor are the main bedrooms, and on the second floor there is an office, the wife’s workshop and a guest room. And a bathroom for guests.