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Ashrae fundamentals calculation - heat transfer off insulated pipe.

Ashrae fundamentals calculation - heat transfer off insulated pipe.

(OP)
Hi,
I've been setting up a calculation following the heat transfer calculations outlined on pages 4.3 & 4.4 of the ashrae fundamentals handbook (2017). I've been using their example to check my spreadsheet before adapting for my actual calculation.
The problem is I can't seem to get all the numbers to pan out. I was wondering if someone else could crosscheck for me to see if it is me or the document that is wrong.

I don't really want to post the actual text for copyright infringemnt reasons, but I am getting different answers for both R2 & R3.
The stated results are
R2 = 3.37*10^(-5) h.degF/Btu
R3 = 0.254 h.degF/Btu

The results I am getting are
R2 = 2.82*10^(-6) h.degF/Btu
R3 = 0.021 h.degF/Btu

In both cases I am out by a factor of 12 which is obviously a feet-to-inches conversion, but in the context of how the information is presented this does not make sense.

RE: Ashrae fundamentals calculation - heat transfer off insulated pipe.

I don't use ASHRAE so I would not be familiar with the formula. From what you revealed, the only thing that I can think of, is the thickness of the insulation; one equation has feet for the thickness and the other thickness is in inches.

RE: Ashrae fundamentals calculation - heat transfer off insulated pipe.

Are the conductivity values in BTU/hr.in.F or Btu/hr.ft.F? If the value is in inches, consider pipe length in inches.

RE: Ashrae fundamentals calculation - heat transfer off insulated pipe.

(OP)
Iguess that is it, thanks Quark!

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