A survey on measuring wall height

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When measuring the wall height to determine the wall area, it's clear the measurement should be floor to floor for return air plenums. Then the appropriate percentage is used in the wall-to-plenum heat gain field of the System's duct system data.

How many HAP users still measure floor to floor when there is ducted return? Have you then entered the wall area by measuring floor to ceiling to check the effect on the load? What is that effect?

It is such a hassle to re-enter the wall area if the system changes from return air plenum to ducted return. It would seem the safest assumption is to enter wall areas by measuring wall height from floor to floor. Do you agree?

Reba Schaber Mechanical Engineer, P.E.
LEED Accredited Professional
1660 N. Alvernon Way Voice: (520) 731-2060
Tucson, Arizona 85712 Fax: (520) 731-2061
rschaber at phmech.com

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I measure floor to floor whether I have return air plenums or ducted

My thinking is that there is heat gain/loss through the wall portion above a
ceiling and below the floor above whether there is air flowing through it
(RA plenum) or not (ducted returns).

I have not tried any of the testing you've suggested, but now that you
mention it, I might play with it a bit to see what happens.

Michael L. Hardy, PE, F.NSPE
Black Oak Engineering, Inc.
Cell 503.314.5244

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On Thu, Feb 17, 2011 at 11:17 PM, Michael Hardy <


Thanks and Best Regards,


Varun Kulkarni , M.S. , EIT

RMF Engineering

5520, Research Park Drive, Suite 300

Baltimore, MD - 21228

Office : 410-576-0505 ext. 5352

Mobile: (+1)405-385-1928

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