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 sanitationŹródło: https://en.wikipedia.org/wiki/Boiler
Definition of boiler
A boiler is a closed vessel in which water or other fluid is heated.
About plumber - definition
A plumber is a tradesperson who specializes in installing and maintaining systems used for potable (drinking) water, sewage and drainage in plumbing systems. The term dates from ancient times, and is related to the Latin word for lead, "plumbum".
The word "plumber" dates from the Roman Empire.3 The Latin for lead is plumbum.
Roman roofs used lead in conduits and drain pipes4 and some were also covered with lead, lead was also used for piping and for making baths.5 In medieval times anyone who worked with lead was referred to as a plumber as can be seen from an extract of workmen fixing a roof in Westminster Palace and were referred to as plumbers "To Gilbert de Westminster, plumber, working about the roof of the pantry of the little hall, covering it with lead, and about various defects in the roof of the little hall".6 Thus a person with expertise in working with lead was first known as a Plumbarius which was later shortened to plumber. Źródło: https://en.wikipedia.org/wiki/Plumber
minor plumbing repairs done in the kitchen Home handymen are very fond carry out the various repair work. Therefore, it happens also that alone make minor repairs or improvements hydraulic.
The houses usually they exchange seals and pipes, which has already gathered a lot of dirt and hair and suds.
Similarly, in flats, where sometimes you also need to fix the toilet flush.
In addition, home handymen often deal with repairs washing machines standing in a bathroom or dishwashers standing in the kitchen.
So they can save some money and demonstrate their efficiency in front of family. But keep in mind that the performance of such work will be possible only if equipped house there are small seals and hydraulic tools..