Repairing boiler? Call in the plumber
There are repair jobs, that almost anyone can do themself, but broken boiler isn't one of them. Boiling hot water and immense pressure - those are the things that define boiler, and also the things you should be wary of.
Calling in professional plumber isn't any shame in this case, it is necessesity. It is different from a ticking bomb, but close enough, especially if the safety valves are at fault. All in all, you need expert on this - let him do his job, and relax. He is aware of the risks involved and already knows how to avoid any mistakes. All you need to do is coffee and maybe some snacks, while he do his job.
If you are not convinced by this, and ready to repair you boiler alone, all i have to add is this: search the internet for movies of exploding boilers, I dare you.
Wikipedia about the history of the plumbers
Quick look in to the history of the plumbers, thanks to Wikipedia:
The word "plumber" dates from the Roman Empire. The Latin for lead is plumbum. Roman roofs used lead in conduits and drain pipes and some were also covered with lead, lead was also used for piping and for making baths. 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". Thus a person with expertise in working with lead was first known as a Plumbarius which was later shortened to plumber.
Different pipes for different purposes
Constructing your plumbing and drainage installation, isn't as straightforward as it may seem. First thing you need to choose, is what type of pipes are you going to use? There is plenty to choose from, but not all are multi purpose and good for your home.
Generally speaking, you need the ones relatively easy to install, repair if needed and with long life span. Price is also relevant, of course, but sometimes it is better to pay up more up front, rather than upgrade it later.
The answer to such problem is only one - PEX pipes. You might thought that copper pipes are better, but they aren't - harder to install and much more expensive. All in all, pipes from PEX are very good, either for the plumber or user. The only thing that's left, is to find were you can get them cheapest, and in required diameters.