What is the difference between Manual J, Manual S, and Manual D?

Manual J calculates the heating and cooling load of the building. Manual S uses those load numbers to select the right equipment — making sure the unit's actual performance data matches the calculated need. Manual D designs the duct system to deliver the right airflow to every room. All three are ACCA standards. Hartzell's Heat & Air applies all three on new construction projects.

Does Hartzell's do new construction outside Kingfisher Oklahoma?

Yes. Hartzell's Heat & Air serves new construction projects throughout central Oklahoma. For geothermal-integrated new construction, the company travels statewide. Call 405-375-4822 to discuss your project location.

New Construction HVAC Design & Load Calculations — Oklahoma

Name: Hartzell’s Heat & Air
Address: 602 S Main St, Kingfisher, Oklahoma, 73750, US
Telephone: 405-375-4822

Hartzell’s Heat & Air handles HVAC installation for new construction in central Oklahoma — Manual J load calculations, equipment selection, and full system installation for new homes and commercial builds. We coordinate with general contractors, electricians, and inspectors to keep your project on schedule. Call 405-375-4822.

Heat loss in winter. Heat gain in summer. That’s what your HVAC system is fighting every hour of every day. The only way to win — with lasting comfort and controlled energy costs — is to calculate it correctly before the equipment is ever selected. Hartzell’s Heat & Air designs every new construction HVAC system using ACCA Manual J, S, and D standards. Not rules of thumb. Not square footage guesses. Actual engineering.

405-375-4822 · New construction estimates & design consultations available

Why Most New Homes Get This Wrong

Hartzell’s Heat & Air service van at a new construction log home install in Oklahoma — A recent new construction install in central Oklahoma — complete HVAC system from rough-in through commissioning.

The most common HVAC mistake in new construction has nothing to do with the brand of equipment. It’s the size. Most contractors in Oklahoma pick equipment based on a square footage rule of thumb — typically 1 ton per 500 square feet, or something similar. That number ignores everything that actually determines your load:

Insulation values in walls, ceiling, and floor
Window area, orientation, and glazing type
Ceiling height and volume
Air infiltration and envelope tightness
Local design temperature (Oklahoma summers hit 100°F+)
Internal heat gains from people, lights, and appliances
Shade, overhangs, and solar exposure

An oversized system short-cycles — it blasts on, hits setpoint quickly, shuts off, and never runs long enough to dehumidify the air. You end up with a clammy, uncomfortable house even when the thermostat reads 74°F. An undersized system runs constantly and still can’t keep up on the hottest Oklahoma days. Both outcomes are avoidable with a proper load calculation.

The ACCA Standard: Manual J, S, and D

The Air Conditioning Contractors of America publishes the engineering standards that define how HVAC systems should be designed for residential and light commercial buildings. Hartzell’s is an ACCA member and applies all three manuals on every new construction project:

Manual J — Load Calculation

Calculates the exact heating and cooling BTUs your home requires based on your specific construction, climate data, and occupancy. This is the foundation everything else is built on. Without a Manual J, all downstream decisions are guesses.

Manual S — Equipment Selection

Uses the Manual J load numbers to select equipment whose published performance data actually matches your calculated need — at your local design conditions. Not the nominal capacity on the label. The actual capacity at 95°F outdoor temperature when it matters most.

Manual D — Duct Design

Designs the duct system to deliver the right CFM of conditioned air to every room. Proper duct sizing, layout, and static pressure design is what makes the difference between a house with one cold room and a house that’s even throughout.

What Hartzell’s Provides for New Construction

Manual J load calculation — Full room-by-room heat loss and heat gain analysis
Equipment recommendation (Manual S) — Brand, model, and capacity matched to your load at Oklahoma design conditions
Duct layout and sizing (Manual D) — Supply and return design for balanced airflow throughout the home
Geothermal feasibility assessment — New construction is the best time to evaluate geothermal; loop field can be integrated before landscaping and flatwork
Builder and architect coordination — We work directly with your project team to locate mechanical rooms, chase spaces, and penetrations before framing is complete
Energy efficiency advisory — Guidance on insulation, window spec, and envelope decisions that affect your HVAC load and long-term utility costs
Full installation — Equipment, ductwork, refrigerant lines, controls, and startup

Why Geothermal Belongs in the New Construction Conversation

If you’re building new, geothermal deserves serious consideration. The loop field can be installed before the yard is finished — eliminating the disruption and extra cost of retrofitting later. Oklahoma’s stable ground temperatures (58–62°F year-round) and open land make it one of the best states in the country for ground source heat pumps. Oklahoma utility rebates — including up to $2,000/ton through CKenergy and other co-ops — can significantly offset installation costs.

Hartzell’s holds IGSHPA Accredited Installer certification and ClimateMaster GeoElite Dealer status — the two most demanding geothermal credentials in the HVAC industry. Learn more about geothermal ›

Our Credentials

ACCA Member — Air Conditioning Contractors of America. All designs follow Manual J, S, and D.
IGSHPA Accredited Installer — Ground source heat pump certification. One of very few in Oklahoma.
ClimateMaster GeoElite Dealer — Factory-trained by the leading U.S. geothermal manufacturer.
Trane Comfort Specialist — TCS SELECT — Elite Trane dealer. Factory-backed installation support.
Mitsubishi Diamond Dealer — Highest Mitsubishi tier. 12-year warranty eligible installations.
NATE Certified — North American Technician Excellence certification.
Oklahoma Mechanical Contractor #00115936 — Required for all HVAC work in Oklahoma.
OSU Engineering Background — Founder Dave Hartzell brings an engineer’s approach to every system design.

Frequently Asked Questions

What is a Manual J load calculation?
Manual J is the ACCA industry standard for calculating the heating and cooling load of a building. It accounts for insulation levels, window area and orientation, ceiling height, air infiltration, local climate data, and occupancy. The result is the exact BTU capacity the HVAC system needs to maintain comfort without wasting energy. Oversized systems short-cycle, cause humidity problems, and wear out faster. Undersized systems can’t keep up. Manual J eliminates the guesswork.

Do I need a load calculation for new construction HVAC in Oklahoma?
Yes. Oklahoma’s climate demands both serious cooling capacity in summer and meaningful heating in winter. A proper Manual J ensures your system is sized for your specific home — not based on square footage rules of thumb that ignore insulation, windows, and orientation. Hartzell’s performs Manual J on every new construction project.

What is the difference between Manual J, S, and D?
Manual J calculates the heating and cooling load. Manual S uses those numbers to select equipment whose actual performance matches the calculated need. Manual D designs the duct system to deliver the right airflow to every room. All three are ACCA standards. Hartzell’s applies all three.

Can Hartzell’s work directly with our builder or architect?
Yes. We work directly with builders, general contractors, and architects. We can review plans and advise on mechanical room placement, duct routing, and equipment selection early in the process — before decisions are made that are expensive to change later.

Does new construction HVAC qualify for the federal tax credit?
No. Both the Section 25D geothermal credit and the Section 25C air-source credit expired December 31, 2025. Neither is available for 2026 installs. Oklahoma utility rebates remain fully active. CKenergy pays $2,000/ton (up to $24,000) in 10 counties including Canadian and Blaine. OG&E pays $1,000/ton. Cimarron Electric, KPWA, CVEC, and OEC also offer rebates in their service territories. Call 405-375-4822 and I will confirm which rebates apply to your project.

Related Services

Manual J Load Calculations
Geothermal for New Construction
HVAC Zoning Systems
Financing & Tax Credits

Barndominium HVAC — New Construction in the Field

These photos are from a new barndominium event venue in central Oklahoma. Hartzell’s handled the full HVAC scope: spray foam building envelope consultation, Manual J load calculations, equipment selection, and installation of a Johnson Controls split-type heat pump system. The result is a comfortable, energy-efficient event space that handles Oklahoma’s wide temperature swings.