Apparatus for heating and steam generating, namely stoves, part of heating installations, boilers for central heating and natural gas installations (boilers), steam boilers, exchangers, burners, equipment for heating systems, water heaters used also as heating system, water heaters, thermosiphon, namely refers to a method of passive heat exchange based on natural convection which circulates liquid in a vertical closed-loop circuit without requiring a conventional pump, radiators, heat pumps, electrical water boilers used for parts of installation, solar energy collectors and apparatus, water heating unit with solar energy and parts thereof, water heaters used for parts of installation with electrical, solid, household, gas fuels, combination boiler, boilers and central heating boilers, bathroom heaters