National Standard (Stillwater, OK) 4.5 MMBTU Makeup Air Heater Retrofit

Project overview

National Standard operates industrial manufacturing in Stillwater, Oklahoma. This project was in their Paint & Coat Building, where tempered outside air is critical for:

• keeping processes stable
• controlling fumes and odors through proper exhaust makeup
• maintaining workable conditions for people and product quality

The existing makeup air heater was very old and at the end of its useful life. The facility also needed more dependable heat capacity, especially when Oklahoma cold snaps show up at the worst time (mid-January is a classic “why did we wait?” moment).

What we installed (and why it mattered)

The replacement was a gas-fired makeup air unit sized around 4.0–4.5 MMBTU/hr. In practical terms, this is the kind of heater that looks simple on paper and becomes a scheduling and safety project in the real world because:

• it’s heavy and awkward (rigging matters)
• it’s connected to high-stakes systems (gas + flame safeguard + high limits)
• it lives at the intersection of HVAC, sheet metal, electrical, and safety controls

Project challenges (the stuff you don’t see on a quote)

Challenge 1: Lead time and “winter urgency”

The facility knew they needed the replacement—then the decision window shrank as the weather got colder. A common Oklahoma pattern is:

• October: “We should replace that heater.”
• January: “We need it now.”

In reality, many commercial/industrial MAU heaters have multi-week to multi-month lead times (we’ve seen 13-week lead times often enough that we plan for it). Waiting forces everyone into a corner:

• expedited logistics
• harder scheduling
• more risk of downtime during the coldest weeks

Challenge 2: Rigging and safe set

A heater retrofit can be “easy” mechanically and still be dangerous if rigging is sloppy. We planned for:

• delivery timing
• cranage / lift planning
• safe setdown and staging so nobody gets hurt

Challenge 3: Duct transitions and “hole in the wall” reality

This install required coordinated sheet metal work where the unit ties into the building. We were able to make specialty sheet metal to:

• adapt duct transitions cleanly
• seal connections properly
• make sure airflow went where it was supposed to go (intake, heat section, discharge)

Scope of work (what we did)

This was a true retrofit: remove old equipment, set new equipment, and commission it properly.

Mechanical + sheet metal coordination

• removed the existing unit
• set the new makeup air heater
• coordinated duct tie-ins and transitions

Electrical

The good news with many retrofits is that existing power is often adequate—especially because newer equipment tends to be more efficient. We still handled:

• verifying electrical requirements and phase
• installing a new disconnect where required
• confirming safe wiring and grounding

Gas piping and gas train setup

On gas-fired makeup air heaters, the gas “tie-in” is not just a pipe connection. It’s a safety system:

• gas piping to the unit
• new gas regulator where required
• leak checks
• confirming correct firing rate range

Commissioning / startup checklist (the part most people skip)

We performed a startup checklist to verify the unit operated within manufacturer specifications and that all safety devices behaved correctly, including:

• flame safeguard verification
• high limits
• airflow proving / interlocks
• stable operation across the intended firing range

This is where “it runs” becomes “it runs safely, repeatedly, and predictably.”

Oklahoma-specific considerations (Stillwater industrial reality)

Cold snaps + process uptime

Stillwater and north-central Oklahoma can swing hard in winter. When the heater is down, it isn’t only discomfort—it can be a production and quality issue.

Supply chain and pricing volatility

Over the last few years, we’ve built more “real-world” language into proposals because material pricing can move fast due to:

• freight delays
• manufacturer allocation
• tariff changes and policy shifts

That doesn’t mean “panic and overpay.” It means plan early so you can order normally instead of ordering in a crisis window.

Results (what the facility got)

This retrofit delivered:

• higher, more dependable heating capacity for makeup air
• a safer and more stable gas-fired system with modern safeties
• a cleaner, better-sealed duct transition into the Paint & Coat Building

Lessons learned (what we’d tell another facility manager)

1. Don’t schedule MAU heater replacement in January if you can avoid it. Start planning in early fall.
2. Treat commissioning as part of the project, not an afterthought. The gas train and safeguards must be verified.
3. Rigging is part of the scope. The easiest way to turn a good project into a bad one is rushing the lift.

Decision guidance: retrofit vs. limp it through another season

Need makeup air / process HVAC support in Stillwater or the OKC metro?

If your facility depends on makeup air, we can help you plan a replacement that’s safe, predictable, and scheduled around operations. Call (405) 223-9900 or request a proposal.

Disclaimer: This case study is informational and generalized. Actual sizing, code requirements, and commissioning steps depend on facility conditions, OEM documentation, and local inspection requirements. Always follow qualified professional guidance.