A boiler is a closed vessel in which water or other fluid is heated.The fluid does not necessarily boil. (In North America the term "furnace" is normally used if the purpose is not actually to boil the fluid.) The heated or vaporized fluid exits the boiler for use in various processes or heating applications,12 including water heating, central heating, boiler-based power generation, cooking, and sanitation. Źródło: https://en.wikipedia.org/wiki/Boiler
In such matters require specialized knowledge and skills, and such work is also associated with great responsibility, because the slightest error can result in a major accident.Plumbing may involve many issues. Sometimes it will be installation of hydraulic, other times repairing the broken pipe or replace gaskets and scope of such work is very extensive.
Specialists in the field of hydraulics are needed in each region, because each building are installed plumbing.So it is very important work, without which it would be hard for us to get around..