I can see quite easily how persons new to the trade without any experience in plumbing or a engineering background can fail to grasp and understand the principles or methods used. Sometimes I see them doing something a certain way just because they have been taught it and they do not realise WHY it is done that way.
I learnt about system design by actually calculating water flow rates, pump curves, heat transfer rates through different materials and different thicknesses. On larger systems you have to take into account and calculate resistance to water flow from every bend and restriction. I could, if necessary take a radiator from a shelf, measure it, work out how much water goes is in it and actually calculate its output from first principles. This sort of work is the only way that industrial heating and process systems can be designed.
I'm not for one minute suggesting that plumbers should be able to do those calculations but people on the short courses need to understand more the principles and the physics behind the system design.
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I agree, I'm on one of these courses and there's methods in the coursework and 3D software, but I figured there has to be more than that. I'm thinking if you have pipe and you take the outside measurement but it's 1mm wall you're accounting for water that isn't there, or an immersion heater but how much element is in there or is that all ready accounted for, or am I a bit off track there.
When I go for practical I want to try as many methods in an area as possible e.g. pipe bending, not just what's in the book. I've been working in sheet metal and microns make a lot of difference. The method for bending I cut a tube to length first then bend, I worked out how much I gained before hand, and they came out pretty much the same (not a very accurate bender) and very quickly. I always try and look deeper I would be very interested to hear more.