2) the low-water security system has to be tested
3) it is necessary to make a restriction
4) the device forces air to blow vertically against the plates in order to cool the fluid inside
5) there are some instruction to be followed
6) to inspect and to clean the boiler two times a year means to maintain it properly
7)some boilers provide the water to be heated at temperature 120
8) the classification of the boilers depends on the water circulation to be boiled
9) a consideration of the modern manufacturing methods to be used is important