[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-1-en-105":3,"doc-seo-571187-105":53,"doc-detail-571187-en":126},{"code":4,"msg":5,"data":6},0,"success",[7,14,19,24,29,34,39,44,49],{"id":8,"doc_module":9,"doc_module_name":10,"category_name":11,"show_sort_weight":12,"slug":13},11,1,"Template","Presentations",90,"presentations",{"id":15,"doc_module":9,"doc_module_name":10,"category_name":16,"show_sort_weight":17,"slug":18},12,"Resumes",80,"resumes",{"id":20,"doc_module":9,"doc_module_name":10,"category_name":21,"show_sort_weight":22,"slug":23},14,"Invoices",70,"invoices",{"id":25,"doc_module":9,"doc_module_name":10,"category_name":26,"show_sort_weight":27,"slug":28},15,"Posters",60,"posters",{"id":30,"doc_module":9,"doc_module_name":10,"category_name":31,"show_sort_weight":32,"slug":33},16,"Social Media",50,"social-media",{"id":35,"doc_module":9,"doc_module_name":10,"category_name":36,"show_sort_weight":37,"slug":38},17,"Forms",40,"forms",{"id":40,"doc_module":9,"doc_module_name":10,"category_name":41,"show_sort_weight":42,"slug":43},18,"Letters",30,"letters",{"id":45,"doc_module":9,"doc_module_name":10,"category_name":46,"show_sort_weight":47,"slug":48},21,"Paper Templates",5,"papers-templates",{"id":50,"doc_module":9,"doc_module_name":10,"category_name":51,"show_sort_weight":4,"slug":52},158,"General","general-158",{"code":4,"msg":54,"data":55},"ok",{"site_id":56,"language":57,"slug":58,"title":59,"keywords":60,"description":61,"schema_data":62,"social_meta":119,"head_meta":121,"extra_data":123,"updated_unix":125},105,"en","residential-duct-sizing-guide-equal-friction-method","Residential Duct Sizing Guide - Equal-Friction Method","","Residential Duct Sizing Guide provides duct-sizing guidance for typical residential furnace heating and air conditioning using an “Equal-Friction” method based on a fraction drop of 0.10 inches per 100 feet of lineal duct. It includes an air-volume CFM chart that matches rectangular duct heights to equivalent round duct diameters and notes that larger volumes or higher static pressures require job-specific evaluation. It also summarizes basic HVAC duct layout practices, airflow relationships, and installation cautions.",{"@graph":63,"@context":118},[64,80,101],{"@type":65,"itemListElement":66},"BreadcrumbList",[67,71,74,77],{"item":68,"name":69,"@type":70,"position":9},"https://docshare.wps.com","Home","ListItem",{"item":72,"name":10,"@type":70,"position":73},"https://docshare.wps.com/template/",2,{"item":75,"name":36,"@type":70,"position":76},"https://docshare.wps.com/template/forms/",3,{"item":78,"name":59,"@type":70,"position":79},"https://docshare.wps.com/template/residential-duct-sizing-guide-equal-friction-method/571187/",4,{"url":78,"name":59,"@type":81,"image":82,"author":87,"headline":59,"publisher":90,"fileFormat":93,"inLanguage":57,"description":61,"dateModified":94,"datePublished":95,"encodingFormat":93,"isAccessibleForFree":96,"interactionStatistic":97},"DigitalDocument",{"url":83,"@type":84,"width":85,"height":86},"https://docshare.wps.com/thumbnails/residential-duct-sizing-guide-equal-friction-method/571187.png","ImageObject",442,249,{"name":88,"@type":89},"Damian","Person",{"url":68,"name":91,"@type":92},"DocShare","Organization","application/pdf","2026-10-16","2026-10-13",true,{"@type":98,"interactionType":99,"userInteractionCount":9},"InteractionCounter",{"@type":100},"ViewAction",{"@type":102,"mainEntity":103},"FAQPage",[104,110,114],{"name":105,"@type":106,"acceptedAnswer":107},"What method and pressure drop does the guide use for duct sizing?","Question",{"text":108,"@type":109},"It uses an “Equal-Friction” method sized on a fraction drop of 0.10 inches per 100 feet of lineal duct.","Answer",{"name":111,"@type":106,"acceptedAnswer":112},"How does the guide advise choosing duct sizes for airflow (CFM)?",{"text":113,"@type":109},"Use the chart to match air volume (CFM) to rectangular duct dimensions (height) and then select the equivalent round duct diameter for the same CFM.",{"name":115,"@type":106,"acceptedAnswer":116},"What are key ductwork placement and airflow rules mentioned?",{"text":117,"@type":109},"Supplies are on outside walls and returns on inside walls; return air CFM must be equal to or greater than supply air CFM, and last take-off runs should be located 12–18 inches from the end with staggered take-offs to maintain pressure.","https://schema.org",{"og:url":78,"og:type":120,"og:title":59,"og:site_name":91,"og:description":61},"article",{"robots":122,"canonical":78},"index,follow",{"doc_id":124,"site_id":56},571187,1792112387,{"code":4,"msg":5,"data":127},{"doc_id":124,"user_id":128,"nickname":88,"user_avatar":129,"doc_module":9,"category_id":35,"category_name":36,"doc_title":59,"doc_description":61,"doc_content":130,"file_id":131,"file_url":132,"file_type":133,"file_size":134,"view_count":9,"is_deleted":4,"is_public":9,"is_downloadable":9,"audit_status":9,"page_count":9,"language":135,"language_code":57,"site_id":56,"html_lang":57,"table_of_contents":136,"faqs":137,"seo_title":138,"seo_description":61,"update_tm":139,"read_time":4},137451208677,"https://ap-avatar.wpscdn.com/davatar_155a257f0dc6eb9ab79c44ca47cae57d","Residential Duct Sizing Guide  \nThe following duct sizes are based on a fraction drop of .10 inches per 100 feet of lineal duct. This \"Equal-Friction\" method of duct sizing should be adequate for normal residential furnace heating and air conditioning applications. Larger volumes or higher static pressures should be dealt with on an individual job basis.  \nRectangular and Round Duct  \n\n| Air Volume\u003Cbr>CFM | Rectangular Duct Height (inches) |  |  |  |  | Equivalent Round Duct (inches) | Air Volume\u003Cbr>CFM |\n| --- | --- | --- | --- | --- | --- | --- | --- |\n|  | 4\" | 6\" | 8\" | 10\" | 12\" |  |  |\n| 50 | 6 x 4 |  |  |  |  | 5 | 50 |\n| 75 | 6 x 4 |  |  |  |  | 6 | 75 |\n| 100 | 8 x 4 | 6 x 6 |  |  |  | 6 | 100 |\n| 125 | 10 x 4 | 6 x 6 |  |  |  | 7 | 125 |\n| 150 | 10 x 4 | 8 x 6 |  |  |  | 7 | 150 |\n| 175 | 12 x 4 | 8 x 6 |  |  |  | 8 | 175 |\n| 200 | 14 x 4 | 8 x 6 |  |  |  | 8 | 200 |\n| 225 | 16 x 4 | 10 x 6 |  |  |  | 8 | 225 |\n| 250 | 16 x 4 | 10 x 6 |  |  |  | 9 | 250 |\n| 275 |  | 12 x 6 | 8 x 8 |  |  | 9 | 275 |\n| 300 |  | 12 x 6 | 8 x 8 |  |  | 9 | 300 |\n| 400 |  | 14 x 6 | 10 x 8 |  |  | 10 | 400 |\n| 500 |  | 18 x 6 | 12 x 8 | 10 x 10 |  | 11 | 500 |\n| 600 |  | 20 x 6 | 14 x 8 | 12 x 10 |  | 12 | 600 |\n| 700 |  | 24 x 6 | 16 x 8 | 12 x 10 |  | 12 | 700 |\n| 800 |  | 26 x 6 | 18 x 8 | 14 x 10 | 12 x 12 | 13 | 800 |\n| 900 |  | 30 x 6 | 20 x 8 | 16 x 10 | 12 x 12 | 14 | 900 |\n| 1000 |  |  | 22 x 8 | 16 x 10 | 14 x 12 | 14 | 1000 |\n| 1100 |  |  | 24 x 8 | 18 x 10 | 16 x 12 | 15 | 1100 |\n| 1200 |  |  | 26 x 8 | 20 x 10 | 16 x 12 | 15 | 1200 |\n| 1300 |  |  | 28 x 8 | 20 x 10 | 18 x 12 | 16 | 1300 |\n| 1400 |  |  | 30 x 8 | 22 x 10 | 18 x 12 | 16 | 1400 |\n| 1500 |  |  |  | 24 x 10 | 20 x 12 | 16 | 1500 |\n| 1600 |  |  |  | 24 x 10 | 20 x 12 | 17 | 1600 |\n| 1700 |  |  |  | 26 x 10 | 22 x 12 | 17 | 1700 |\n| 1800 |  |  |  | 28 x 10 | 22 x 12 | 18 | 1800 |\n| 1900 |  |  |  | 30 x 10 | 22 x 12 | 18 | 1900 |\n| 2000 |  |  |  |  | 24 x 10 | 18 | 2000 |\n\nHELPFUL BASIC INFORMATION:  \nWhen Cooling: You must have 400 CFM of air flow per Ton of A/C (1 Ton equals 12,000 BTU) Approximately 1 CFM of air is required to heat or cool 1 to 1.25 sq. ft. of floor area.  \nDuct Work  \nSupplies are located on outside walls.  \nReturns are located on inside walls. They should not be located in the same area as the furnace, nor should they be located by moisture sources such as kitchens or bathrooms.  \nReturn Air CFM must be equal or greater than Supply Air CFM.  \nWyes commonly reduce.  \nTees split, but do not reduce, and an appropriate reducer must be added. Dampers on take-off duct runs allow for adjustments of air distribution.  \nIn order to maintain velocity, reduce duct size.  \nNever locate ducts at the end of the trunk line run. Last take-off run to be located 12\" -18\" from end. Always stagger take-off ducts by 12\" to maintain pressure.  \nUse insulated duct or duct board in unheated spaces.  \nFlexible duct work must be stretched tightly for maximum air flow.  \nInformation provided is to be used as a guideline only.","cbCaip9RPKELB4RB","https://ap.wps.com/l/cbCaip9RPKELB4RB","pdf",103398,"English","# Residential Duct Sizing Guide\n## Equal-Friction duct sizing basis\n## Rectangular and Round Duct sizing chart\n## Helpful basic information for HVAC ductwork","[{\"question\":\"What method and pressure drop does the guide use for duct sizing?\",\"answer\":\"It uses an “Equal-Friction” method sized on a fraction drop of 0.10 inches per 100 feet of lineal duct.\"},{\"question\":\"How does the guide advise choosing duct sizes for airflow (CFM)?\",\"answer\":\"Use the chart to match air volume (CFM) to rectangular duct dimensions (height) and then select the equivalent round duct diameter for the same CFM.\"},{\"question\":\"What are key ductwork placement and airflow rules mentioned?\",\"answer\":\"Supplies are on outside walls and returns on inside walls; return air CFM must be equal to or greater than supply air CFM, and last take-off runs should be located 12–18 inches from the end with staggered take-offs to maintain pressure.\"}]","Residential Duct Sizing Guide - Equal-Friction Method | PDF",1791901705]