ASHRAE Journal - May 2009 - 50

Equal Friction Solution for Duct Sizing By Fred W. Dougherty, P Life Member ASHRAE .E., T his article presents an automated quick and simple equal friction solution to calculating duct diameter and pressure loss, using an iterative solution to the Colebrook equation. An initial duct diameter is calculated for duct segment airflows at a Dp/100 ft (Dp/30 m) to be input by the designer. Typical values for supply and return ducts would be 0.09, 0.095, or 0.100 in. w.g. per 100 ft (22.41, 23.66, or 24.9 Pa per 30 m) of duct. In the calculations that follow, this parameter is referred to as dp100. The complete solution requires running two VBasic macros in Excel. A copy of the Excel workbook with the macros can be downloaded at www.ashrae.org/ ashraejournal/duct_size_by_dp100.xls. The solutions and macros presented here will primarily be of interest to 50 ASHRAE Journal algorithms in the spreadsheet will help readers understand how the commercial software works, so that it isn’t simply a “black box.” The method outlined here can be applied to the static regain design method, but that exercise is left to the reader. The Designer’s Problem the independent design engineer who is designing HVAC systems for small commercial projects under 20,000 ft2 (1858 m2), generally using DX unitary equipment. Commercial duct design software normally is used for larger, more complex projects. Reviewing the ashrae.org After laying out the ductwork for an air-conditioning project and computing the airflow to each terminal, the designer knows the airflow and length for each supply and return duct segment, and can select a duct height that is compatible with the geometric constraints in the area where the ducts will be routed. (A segment can be defined as a run of duct About the Author Fred W. Dougherty, P .E., is a building systems consulting engineer in Panacea, Fla. May 2009

ASHRAE Journal - May 2009

Table of Contents for the Digital Edition of ASHRAE Journal - May 2009

ASHRAE Journal - May 2009
Contents
Commentary
Industry News
Letters
Meetings and Shows
     Moving Air for Comfort
Feature Articles
     Lessons Learned in Portable Classrooms
     Using Time-of-Day Scheduling to Save Energy
     Equal Friction Solution for Duct Sizing
     Anniversary Feature: System Application and Design for School Air Conditioning
Building Sciences
InfoCenter
Emerging Technologies
Special Products
Classified Advertising
Advertising Index
ASHRAE Journal - May 2009 - ASHRAE Journal - May 2009
ASHRAE Journal - May 2009 - Cover2
ASHRAE Journal - May 2009 - 1
ASHRAE Journal - May 2009 - 2
ASHRAE Journal - May 2009 - Contents
ASHRAE Journal - May 2009 - 4
ASHRAE Journal - May 2009 - Commentary
ASHRAE Journal - May 2009 - 6
ASHRAE Journal - May 2009 - Industry News
ASHRAE Journal - May 2009 - 8
ASHRAE Journal - May 2009 - 9
ASHRAE Journal - May 2009 - 10
ASHRAE Journal - May 2009 - 11
ASHRAE Journal - May 2009 - Letters
ASHRAE Journal - May 2009 - 13
ASHRAE Journal - May 2009 - 14
ASHRAE Journal - May 2009 - 15
ASHRAE Journal - May 2009 - Meetings and Shows
ASHRAE Journal - May 2009 - 17
ASHRAE Journal - May 2009 - Feature Articles
ASHRAE Journal - May 2009 - 19
ASHRAE Journal - May 2009 - 20
ASHRAE Journal - May 2009 - 21
ASHRAE Journal - May 2009 - 22
ASHRAE Journal - May 2009 - 23
ASHRAE Journal - May 2009 - 24
ASHRAE Journal - May 2009 - 25
ASHRAE Journal - May 2009 - 26
ASHRAE Journal - May 2009 - 27
ASHRAE Journal - May 2009 - 28
ASHRAE Journal - May 2009 - 29
ASHRAE Journal - May 2009 -      Lessons Learned in Portable Classrooms
ASHRAE Journal - May 2009 - 31
ASHRAE Journal - May 2009 - 32
ASHRAE Journal - May 2009 - 33
ASHRAE Journal - May 2009 - 34
ASHRAE Journal - May 2009 - 35
ASHRAE Journal - May 2009 - 36
ASHRAE Journal - May 2009 - 37
ASHRAE Journal - May 2009 - 38
ASHRAE Journal - May 2009 - 39
ASHRAE Journal - May 2009 - 40
ASHRAE Journal - May 2009 - 41
ASHRAE Journal - May 2009 -      Using Time-of-Day Scheduling to Save Energy
ASHRAE Journal - May 2009 - 43
ASHRAE Journal - May 2009 - 44
ASHRAE Journal - May 2009 - 45
ASHRAE Journal - May 2009 - 46
ASHRAE Journal - May 2009 - 47
ASHRAE Journal - May 2009 - 48
ASHRAE Journal - May 2009 - 49
ASHRAE Journal - May 2009 -      Equal Friction Solution for Duct Sizing
ASHRAE Journal - May 2009 - 51
ASHRAE Journal - May 2009 - 52
ASHRAE Journal - May 2009 - 53
ASHRAE Journal - May 2009 - 54
ASHRAE Journal - May 2009 - 55
ASHRAE Journal - May 2009 -      Anniversary Feature: System Application and Design for School Air Conditioning
ASHRAE Journal - May 2009 - 57
ASHRAE Journal - May 2009 - 58
ASHRAE Journal - May 2009 - 59
ASHRAE Journal - May 2009 - 60
ASHRAE Journal - May 2009 - 61
ASHRAE Journal - May 2009 - 62
ASHRAE Journal - May 2009 - 63
ASHRAE Journal - May 2009 - 64
ASHRAE Journal - May 2009 - 64a
ASHRAE Journal - May 2009 - 64b
ASHRAE Journal - May 2009 - 65
ASHRAE Journal - May 2009 - 66
ASHRAE Journal - May 2009 - 67
ASHRAE Journal - May 2009 - 68
ASHRAE Journal - May 2009 - 69
ASHRAE Journal - May 2009 - 70
ASHRAE Journal - May 2009 - 71
ASHRAE Journal - May 2009 - 72
ASHRAE Journal - May 2009 - 73
ASHRAE Journal - May 2009 - Building Sciences
ASHRAE Journal - May 2009 - 75
ASHRAE Journal - May 2009 - 76
ASHRAE Journal - May 2009 - 77
ASHRAE Journal - May 2009 - 78
ASHRAE Journal - May 2009 - 79
ASHRAE Journal - May 2009 - InfoCenter
ASHRAE Journal - May 2009 - 81
ASHRAE Journal - May 2009 - 82
ASHRAE Journal - May 2009 - 83
ASHRAE Journal - May 2009 - 84
ASHRAE Journal - May 2009 - 85
ASHRAE Journal - May 2009 - 86
ASHRAE Journal - May 2009 - Emerging Technologies
ASHRAE Journal - May 2009 - 88
ASHRAE Journal - May 2009 - 89
ASHRAE Journal - May 2009 - 90
ASHRAE Journal - May 2009 - 91
ASHRAE Journal - May 2009 - Special Products
ASHRAE Journal - May 2009 - 93
ASHRAE Journal - May 2009 - Classified Advertising
ASHRAE Journal - May 2009 - 95
ASHRAE Journal - May 2009 - Advertising Index
ASHRAE Journal - May 2009 - Cover3
ASHRAE Journal - May 2009 - Cover4
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_MCDEBX
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_WNYSQY
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XATVOD
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_FJSHSS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_CCBZDS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XDEFVG
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2023november_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2023november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_VHGNBL
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_WPKBNJ
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_UUVCDE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RTGDEW
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2023
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_LKRFXS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_AZSOFG
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ERCDBH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QWDFRV
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JHGVDF
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OPUYHG
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SREIBM
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_LRTGLK
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OKRFGH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2022november_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2022november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_TZSERA
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_LVRUIX
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RPTVYZ
https://www.nxtbook.com/nxtbooks/ashrae/mini_pub_catalog
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XIYTGD
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2022
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RFGDOB
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_PABXNU
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_REMKLS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_PICVBT
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_AOYTVW
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JQOPLS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_IOYTBC
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SGAJJF
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_IGHYER
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_PDRKLS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2021november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2021november_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XCODFR
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QSLFGO
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ILKVNM
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2021
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OPDJKD
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_VJKSRY
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SDHUTC
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JPPKRR
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SDLTTH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_CKLLES
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SLDOX
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_HJETUK
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OLUHGE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2020october
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2020october_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ZERDGH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QVMNEO
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RTPOKE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_BBATRE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_STUBMW
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_TPEMPE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JNMKDS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_FBTTPA
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_WQMMNE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_TVBRYN
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_showguide2020
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_KTUZMA
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ABEDGD
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201910
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201909
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2019septmeber_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2019september
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201908
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201907
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201906
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201905
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201904
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2019april
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201903
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2019march
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201902
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201901
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_showguide2019
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018december
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2018fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2018fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018october
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2018
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201810
https://www.nxtbook.com/nxtbooks/ashrae/ashraeinsights_201806
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201805
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201804
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201803
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201712
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201711
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201710
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2017fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2017fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201709
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201705
https://www.nxtbook.com/nxtbooks/ashrae/ashrae_meetinginsert_201610
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2016fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2016fall
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acrexindia
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2015summer_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2015summer
https://www.nxtbook.com/nxtbooks/amca/2014summer2
https://www.nxtbook.com/nxtbooks/amca/2014summer
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acma_2014summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201311
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201309
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acmasupp_2013fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201305
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201303
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2013winter
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201211
https://www.nxtbook.com/nxtbooks/ashrae/achr_expo_mexico2012
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201209
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201208_v3
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201208_v2
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2012summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201205
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201203
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2012winter
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201111_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201109_v2
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2011summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201105
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201103
https://www.nxtbookmedia.com