Pawel, just trust the engineers on here mate. Follow the rules and get more knowledge and you will see things becoming much easier. The majority of people on here are highly trained and have huge background of plumbing. The engineers did not just spent their hard earned money for endless trainings but also for the knowledge to become a great engineer. A lot of people on here have over 20-40 years experience. I would say stick around here and try to pick other brains knowledge. If you feel ready then please be my guest and go ahead but you may end up having an installation issue and that could cost you money to fix that and not only that but perhaps a customer or more.