U Values

Why have you moved my post from Plumbing to building. Heatloss calculations are used to size radiators this is determined by u values. I requested U values for a plumbing point of view not a builders. U values relate to windows, doors, internal external walls etc does this mean you will move it to window section, carpentry section.

Move the post back as its to do with rad sizing.

bengasman said:

Can't say I have heard the term before

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If the OP wants go go back to first pinciples, he will have to start by proving the Laws of Thermodynamics, Newton's Law of Cooling etc etc

kirkgas said:

i have a paper version of lists of u values for different materials etc, i could scan them and email you if you dont find what you want on the tinternet, repost a reply if/when you want them and we can sort out email address.

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Not sure what you mean by a paper version list of u values for different materials but .... materials per say do not actually have a u value, they have a manufacturers declared thermal conductivity value that is relevant to that particular material ie. phenolic insulation board, the thickness of that board in a calculation will then give you its thermal [/b]resistance value, thereafter each element that makes up the wall is calculated to achieve an accurate u value.
What I am trying to say is you can not generally have a u value for materials with a uniformed u value and simply add them together, its not that simple