Custom Sheet Metal & Ductwork Fabrication — Central Oklahoma
Hartzell’s Heat & Air fabricates custom sheet metal ductwork in-house in Kingfisher, Oklahoma — plenums, custom fittings, transitions, and full supply/return systems. In-house fabrication means faster turnaround and exact fits for unusual spaces that off-the-shelf parts can’t handle. Call 405-375-4822.
Hartzell’s fabricates and installs square metal ductwork built for your specific building — not adapted from whatever’s on a shelf. We run our own sheet metal shop, design systems with Manual D calculations, and rough in new construction ductwork that fits the framing rather than fighting it.
Sheet Metal & Ductwork Services
From a single custom fitting to a full new-construction rough-in, we handle the complete range of sheet metal and ductwork work:
Custom Ductwork Fabrication
Built to your exact specs in our own shop — not adapted from stock pieces.
New Construction Rough-In
Full duct layout and installation coordinated with framing and other trades.
Retrofit & Replacement
Replace deteriorated, undersized, or poorly designed existing duct systems.
Duct Modification & Rerouting
Adding registers, extending runs, or rerouting for additions and remodels.
Leak Detection & Sealing
Mastic sealant and metal tape — the right materials, not more duct tape.
Custom Transitions & Plenums
Precision-fabricated fittings for unusual configurations.
Commercial Sheet Metal
Large-scale fabrication for commercial HVAC, restaurants, and industrial.
Exhaust & Ventilation Ductwork
Kitchen exhaust, bathroom fans, dryer vents, commercial ventilation.
How We Do It Differently
In-House Fabrication
We run our own sheet metal shop. That means we build exactly what the job needs — not whatever’s closest on a shelf — and we can turn parts around fast without waiting on a supplier.
Manual D Duct Design
We size duct systems using ACCA Manual D calculations based on the Manual J load. Properly sized trunk lines and branch runs mean correct static pressure and balanced airflow throughout the building.
Square Metal — Not Just Flex
We install square and rectangular sheet metal trunk lines as the backbone of every system. Flex duct has its place for short final runs to registers — not as a shortcut through a whole house.
New Construction Experience
We coordinate with framers, plumbers, and electricians to rough in ductwork that fits the building — not ductwork that fights it. Proper rough-in avoids the expensive corrections that show up at final inspection.
Why Ductwork Quality Matters
The duct system is the delivery mechanism for everything your HVAC equipment produces. A properly sized, properly sealed metal duct system is the difference between a building that’s comfortable everywhere and one with hot spots, cold rooms, and a system that runs non-stop:
Duct Leakage
The EPA estimates 20–30% of conditioned air is lost through duct leaks in a typical home. That’s money leaving your building every hour the system runs.
Undersized Ducts
High static pressure from undersized trunk lines overworks the blower motor, increases noise, shortens equipment life, and reduces airflow to every register on the system.
Poor Layout
A duct layout that doesn’t match the building’s load distribution creates permanent hot and cold spots no amount of thermostat adjustment will fix.
Flex Duct Abuse
Kinked, compressed, or over-extended flex duct can reduce airflow by 50% or more. It’s a shortcut that costs more in energy and comfort than it saves in installation time.
New Construction Rough-In
We work with builders from initial layout through final commissioning. Our new construction process:
New Construction HVAC services ›
How We Design a Duct System
Before a single piece of metal gets cut, we work out the duct system on paper. Load calculations determine how much heating and cooling each room needs; duct sizing calculations determine what it takes to deliver it. These aren’t guesses — they’re engineering. Here’s what that process looks like on an actual Hartzell’s job:
Actual duct design drafts and load calculation sheets from Hartzell’s jobs. Manual J determines room-by-room heating and cooling loads; Manual D determines the trunk sizes, branch runs, and fittings needed to deliver those CFMs at the right static pressure.
Manual J — Load Calculation
Calculates the actual heating and cooling load for each room based on square footage, insulation, windows, orientation, and internal gains. This is the foundation — get it wrong and everything downstream is wrong too.
Manual D — Duct Design
Uses the Manual J outputs to size every trunk line, branch run, and fitting so the system delivers the right CFM to each room at a static pressure the equipment can handle. Undersized or oversized ducts both create problems.
In-House Fabrication to Spec
Once the design is done, we cut and fabricate the trunk lines, transitions, and plenums in our shop to match the calculations exactly. The field crew installs from engineered drawings, not guesswork.
Frequently Asked Questions
Serving Central Oklahoma
Sheet metal fabrication and ductwork installation throughout Kingfisher, Blaine, Oklahoma, Canadian, Logan, Garfield, and Major counties. Full service area ›
Common HVAC Questions › · Current Specials › · Equipment Warranties › · See Pricing ›
Nearby Communities We Serve
Custom Ductwork or Sheet Metal Project?
In-house fabrication. Manual D design. Free estimates.
Our Job Isn’t Done Until You’re Satisfied
- Your system is running, tested, and set to your preferred temperature
- You understand how to operate your new equipment or thermostat
- The work area is clean — we take our trash with us
- You have documentation for manufacturer warranty and any applicable rebates
- Every question you have is answered before we leave the driveway
Written by Dave Hartzell — Owner, Hartzell’s Heat & Air. Master HVAC License #00115936. Serving central Oklahoma for 15+ years.