Looking for a Manual J calculation in San Marcos, TX? Describe your project once and up to three HVAC designers who work in San Marcos and Hays County get back to you with a quote. It's free and there is no obligation.
San Marcos is home to about 74,316 people (2024 Census Bureau estimate), a growing community (+9.6% since 2020). With 1,861 people per sq mi, it is a suburban area. HVAC permits here increasingly require load calculations, especially for new homes and heat pumps.
San Marcos at a glance
- Population (Census Bureau estimate, 2024)
- 74,316 (+9.6% since 2020)
- Rank in Texas
- 56th of 1,224 cities and towns
- Land area
- 40 sq mi
- Population density
- 1,861 people per sq mi (suburban)
- Type
- City (San Marcos city)
- Main county
- Hays County
What to check before hiring in San Marcos
- Requirements: in Texas, 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 San Marcos
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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 San Marcos
How much does a Manual J cost in San Marcos, TX?
It depends on the home and the reports needed. Describe your project: designers who serve San Marcos 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 San Marcos 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.