Looking for a Manual J calculation in Duncan, OK? Describe your project once and up to three HVAC designers who work in Duncan and Stephens County get back to you with a quote. It's free and there is no obligation.
Duncan is home to about 23,174 people (2024 Census Bureau estimate), a growing community (+2.2% since 2020). With 540 people per sq mi, it is a semi-rural area. HVAC permits here increasingly require load calculations, especially for new homes and heat pumps.
Duncan at a glance
- Population (Census Bureau estimate, 2024)
- 23,174 (+2.2% since 2020)
- Rank in Oklahoma
- 22nd of 591 cities and towns
- Land area
- 43 sq mi
- Population density
- 540 people per sq mi (semi-rural)
- Type
- City (Duncan city)
- Main county
- Stephens County
What to check before hiring in Duncan
- Requirements: in Oklahoma, ask the building department what report format it expects.
- Inputs: accurate plans and window data make the calculation reliable.
- Volume: builders can often get pricing for several homes.
- Price drivers: home size, number of zones and whether S and D are included.
Useful official resources
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ACCA: Air Conditioning Contractors of America
Official information and guidance.
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ICC: International Code Council
Official information and guidance.
Services available in Duncan
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Manual J load calculation
Room-by-room heating and cooling load calculation for the HVAC permit.
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Manual S and D equipment and duct design
Equipment selection and duct design from the load calculation.
Frequently asked questions in Duncan
How much does a Manual J cost in Duncan, OK?
It depends on the home and the reports needed. Describe your project: designers who serve Duncan reply with a quote.
How long does it take?
Often a few days once plans are received.
Can it be done remotely?
Usually yes, from plans and specifications.
Which HVAC designers will contact me?
Up to three independent HVAC designers who serve Duncan and the surrounding area, chosen for the service you need. Your details are shared only with your consent.
Source: U.S. Census Bureau, Population Estimates Program (Vintage 2024) and Gazetteer Files (public domain), imported on 10/31/2026. Figures describe the incorporated place or county as published; they are shown for information only.