Does anyone know a web site that could give me informationg on these 2 topics? I failed my plumbers exam because of them. In Ontario Canada they switched the code book from Interprovincial to National(canada). Ontarion government didn't want this, but had no choice. So they decided to take it out on the Colleges by not changing the schools programs. Which now left the apprentices out in the dark. Because they do not teach us Hydronic heating or cooling systems in school. So needless to say unless you've actually working in the filed on these your screwed. Me being a residential low rise plumber, makes me extra screwed lol. So if anyone can help me out that would be great.