15+ years • 6,500+ jobs completed • 1,500+ Oklahoma homes served
Dave Hartzell · Experience
The career that built the operator
Before Hartzell’s Heat and Air, I spent a 47-year career in HVAC and building systems. The biggest chapter was running a hardened, mission-critical long-distance switch for Sprint in Fort Worth, against a federal deadline, under budget, with zero FCC-reportable issues. This page is where I tell those project stories straight. More get added as I write them up.
Career projects
A series. Each card is one project, told first-person with the real facts. Project #1 is the deep one, the Sprint Fort Worth switch, featured in full below. The rest fill in over time.
The Sprint Fort Worth mission-critical switch
Recruited by Sprint to run a roughly $34M expansion of a hardened national-carrier long-distance switch. Four independent power feeds, 60-day off-grid autonomy, McQuay chillers, Andover controls, beat the federal E911 deadline. Full story below.
Statewide: field engineer for Sprint’s Texas network
After the Fort Worth switch, Sprint made me the field engineer for their sites across the whole state of Texas. I took on the PCS wireless side, installs and upgrades, and I did Andover building-controls work across the sites, both the wireline switch side and the PCS wireless side. In that era Sprint ran on the order of 22,500 to 25,000 cell sites nationally, and I covered the Texas field.
My own job-site photos caught a lot of those PCS tower sites, the lattice towers, the equipment shelters, the fenced compounds, right alongside the switch build. The throughline is simple: one engineer who could walk into any of their Texas buildings and work the controls and the systems.
That is the work I carry straight into your building today: building automation, monitoring, and predictive maintenance, now AI-assisted. Watch the system, trend it, and fix it before it fails.
Building automation and free cooling
Enterprise controls, the 3x payback rule, and early free-cooling work, before the data-center world made it standard.
Geothermal in Kingfisher and Central Oklahoma
The work my shop is known for today: IGSHPA-accredited geothermal design and installation across northwest Oklahoma.
Featured project
The Fort Worth switch: the biggest project I ever ran
Sprint recruited me to run it. It was a hardened long-distance switching building in Fort Worth, Texas, expanded over a year to carry Sprint’s E911 mobile-location buildout. We beat the deadline, came in under budget, and finished with zero FCC-reportable issues. On a live carrier facility carrying emergency-services traffic, that last number is the one that matters.
How Sprint came and got me
I didn’t walk in the front door. I backed into that building the hard way, through maintenance nobody else wanted. It was so high-priority that every footstep through it took a written procedure, and most vendors wouldn’t put up with that scrutiny. I did the work right, and after a year Sprint started handing me more buildings.
When the big project came on, Sprint wanted me on it. Company policy meant they had to offer the role to all of their roughly 80,000 employees first, so to bring me in from the outside they wrote the position in my favor and hired me directly. They paid me an engineer’s retainer to be ready to be at any of their sites on command. I priced myself like the engineer I was, not a maintenance man.
The hardened switch
This is the part most people never see. The building was built to survive on its own for 60 days, no outside power and no outside water, keeping the switch running and the people inside safe with the doors shut. That is the whole point of a carrier switch: the long-distance network cannot go dark.
Four independent power supplies
- Fort Worth 911 emergency-grade grid feed
- Dallas 911 emergency-grade grid feed, a second city so one metro going down can’t take the switch
- On-site generators with diesel storage sized for long-run autonomy, fed by a fuel tank dug into the ground
- The largest battery bank on site, the DC plant that carries the load with zero interruption during any transfer
Two of those feeds came in as dual 14,400-volt (14.4 kV) lines off the 911 grids. Getting tied into two separate cities’ emergency systems took real lobbying. Add large on-site water tanks and you have the 60-day number made real.
Every one of those systems, the high-voltage gear, the generators, the fuel and water storage, the controls, is something I was trained on and knew how to work on. That’s what Sprint paid the engineer’s rate for.
Built for expansion: twenty years ahead
The building was engineered from the start to take three more stories and two more chillers on top of what we installed. You don’t pour that much foundation for the load you have. You build it for the load you’ll have. The cooling lived in the mechanical room on McQuay chillers, sized and piped to carry far more than day-one demand. That headroom is the whole “twenty years ahead” idea, built right into the steel.
The controls, run from Kansas
The building ran on Andover Controls, very specialized for that era. Sprint is named on Andover’s own published customer list, alongside places like Rockefeller Center. An unmanned, hardened site in Fort Worth, with its environment monitored and run from a secure operations center in Kansas hundreds of miles away. That is enterprise building automation at carrier scale, and it’s a thing I did, not a thing I read about.
The 12-star deadline we beat
The whole expansion existed to house Sprint’s E911 Phase II location equipment, the federal mandate that forced wireless carriers to deliver a 911 caller’s actual location, not just the nearest tower. We went from the old three-satellite fix to a system that locked up to twelve, twelve “stars,” accurate enough to tell which pocket your phone was in. The FCC’s phase-in deadline was October 1, 2001. We finished the build that summer and fall and beat it.
Watch: the Fort Worth switch, in 2,750 photos
The story in Dave’s own words, the 6.5-minute build, told start to finish, narrated over roughly 2,750 photos from the job.
The building today
The building is still standing at 1400 E Presidio Street in Fort Worth, and it’s still doing mission-critical work, only now for everyone, not just Sprint. Sprint merged into T-Mobile, and in 2022 the legacy long-haul network sold to Cogent Communications, which converted the biggest old switch buildings into colocation data centers. This is one of them: about 110,000 square feet, roughly 14 MW of power, listed for sale in 2025 at $140 million.
That’s the “twenty years ahead” point made literal. We built that place overbuilt for a converged-data future, the power, the cooling, the headroom. Today the building I hardened for a Sprint long-distance switch is a nine-figure data center, doing exactly the kind of work it was built ahead of its time to do. The bet was right. It just took the world about twenty years to catch up to the building.
What that work means for you today
So do I know mission-critical? Yes. In the most critical way there is: data. I lived it. I was never more than fifteen minutes from that site for years, ready on command. That job took me from a field technician to a building network engineer, and it is the foundation under everything I offer national chains and their facility-maintenance vendors now.
When I tell a national account I understand a hardened building, the power, the cooling, the controls, the redundancy, the federal scrutiny, I’m not reading it off a brochure. I built one, ran one, and was on call for it for years.
Automation and predictive maintenance
I ran enterprise building automation (Andover controls) across carrier sites all over Texas, the systems that turn the cooling and power on and off and watch them around the clock. Today, with modern tools, I can do more of it than ever. And here’s the discipline I carried straight into my own shop: on a carrier network you don’t wait for it to break. You monitor it, you trend it, and you get it checked before it fails, because a failure is a federal event and lost customers. That’s why I push maintenance and proactive checks instead of waiting for the 2 a.m. breakdown. Catch it on the trend, fix it on your schedule, not the system’s.
It’s the same discipline whether it’s a Sprint switch or a furnace in Kingfisher. Don’t wait till it breaks. Monitor it, trend it, maintain it.
Call 405-375-4822 See my maintenance plans →
Questions about the Sprint project
What was the Sprint Fort Worth project Dave Hartzell ran?
It was a roughly $34 million expansion of a hardened national-carrier long-distance switch in Fort Worth, Texas. Sprint recruited Dave to run it on the ground over a one-year build to carry Sprint’s E911 mobile-location equipment. It came in under budget, beat the federal deadline, and finished with zero FCC-reportable issues.
What made the building mission-critical?
It was built to run on its own for 60 days with no outside power or water. It had four independent power supplies, including dual 14.4 kV feeds off the Fort Worth and Dallas 911 emergency grids, on-site generators with buried diesel storage, and the largest battery bank on site. McQuay chillers handled the heat, and Andover controls ran the environment, monitored from a Kansas operations center.
Does this experience apply to commercial and national-account work?
Yes. Running a hardened, federally scrutinized carrier building is the foundation for the commercial and national-chain HVAC work I do now. I understand power, cooling, controls, redundancy, and the readiness a mission-critical building demands, because I built and ran one.
Can Dave do building automation and predictive maintenance?
Yes. I ran enterprise Andover building automation across carrier sites all over Texas, the systems that control and monitor cooling, power, and environment around the clock. With modern tools I can do more of it than ever, and I bring the same monitor-and-trend, fix-it-before-it-fails discipline to every customer.
What is the building used for now?
It’s at 1400 E Presidio Street in Fort Worth and is now an operating Cogent data center, about 110,000 square feet with roughly 14 MW of power. It was listed for sale in 2025 at $140 million. The building Dave hardened for a Sprint switch does mission-critical data work today.
Mission-critical discipline, brought home to Oklahoma
Whether it’s a national chain’s rooftop, a commercial site, or a furnace in Kingfisher, you get the same standard: monitor it, trend it, maintain it, and tell you straight what it costs before any work starts. 4.8 stars across 300+ reviews.
Call 405-375-4822