Recirculating Untempered Make-Up Air Unit
You need to replace exhausted air and hold building pressure, but the space does not justify the cost of tempering. A recirculating untempered make-up air unit moves air and balances pressure without heating or cooling the supply.
It reuses indoor air, so operating cost stays low.
We match units across multiple manufacturer lines to your airflow and controls, not to one factory’s catalog. Every unit is US-made and backed by the manufacturer’s warranty, and we handle any warranty issue with the factory directly.
Have questions? Need a quote?
We are the authorized distributors for the leading American manufacturers of indirect gas-fired make-up air units. We’ll be pleased to provide the ideal make up air unit for your application as authorized representatives.
For a fast quote or if you have inquiries about commercial or industrial MUA, get in touch with us.
How Recirculating Untempered Make-Up Air Units Work
The unit replaces your exhausted volume and holds building pressure, with no heat or cooling added to the supply.
- Pulls return air from the space and blends in a set fraction of outdoor air through a mixing box.
- Dampers hold the recirculation-to-outdoor-air ratio and modulate against the exhaust load.
- No burner or coil in the airstream, which keeps the energy draw low.
If your application needs warmed supply air, a heated recirculating make-up air unit runs the same logic with a heat source added.
Have questions? Need a quote?
Recirculating Untempered MUA Specifications and Configurations
Sizing follows your exhaust volume and the recirculation-to-outdoor-air ratio your application allows. Use the figures below as planning ranges, then confirm against your exhaust load with our make-up air sizing calculator.
| Parameter | Typical Range or Option |
|---|---|
| Airflow (CFM) | Roughly 800 to 15,000 for modular units, higher on large industrial builds |
| Recirculation / outdoor-air ratio | Adjustable, from high recirculation with minimum outdoor air to full outdoor air |
| Fan type | Belt-driven or direct-drive, forward-curved or backward-inclined |
| Motor and drive | Single-speed, two-speed, or VFD for variable volume |
| Air control | Mixing box with modulating outdoor-air and recirculation dampers, exhaust interlock |
| Filtration | Intake filters, configurable by application |
| External static pressure | Set by ductwork and diffuser layout |
| Tempering | None (see the untempered make-up air range for related configurations) |
Where Untempered Recirculating Make-Up Air Works Best
Untempered recirculation fits when the priority is pressure relief and air movement, and the space tolerates supply air at or near indoor temperature. It also pulls warm ceiling air down in tall spaces, which evens out temperatures without a heat source.
| Good Fit | Spec Tempering Instead |
|---|---|
| Mild or temperate climates | Cold climates with low winter design temperatures |
| Transitional or shoulder-season operation | Year-round comfort or process temperature targets |
| Warehouses and distribution centers | Commercial kitchens and process spaces needing tempered supply |
| Cleaner industrial spaces where unconditioned supply is acceptable | Draft-sensitive occupied areas |
When the building runs cold and needs warmed replacement air, move up to the make-up air unit range and compare tempered configurations.
Why Engineers Spec Recirculating Untempered MUA With Us
We carry multiple manufacturer lines, so the unit we spec is the one that fits your airflow and controls, not the one we happen to stock. You get an honest match instead of a sales pitch for a single catalog.
Every unit is US-made and backed by the manufacturer’s warranty.
If a warranty issue comes up, we handle it with the factory directly, so you are not chasing a manufacturer on your own. That is the difference between buying a box and having an application partner.
Tell us your exhaust volume and your space, and we will size the unit and confirm the configuration. Call 847-262-3457 ext. 23 to start.