Designed to bring fresh outside air into the paint booth. Non-tempered. Heated options available upon request.
| Heat source | Best for | Notes |
|---|---|---|
| Natural gas | Production shops with gas service | The most common choice. Direct-fired or indirect-fired burners, high heat output and low operating cost. |
| Propane | Remote sites, outdoor booths, no natural gas | Same performance as natural gas, configured for a propane supply. |
| Electric | Sites without gas, clean rooms, sensitive facilities | No combustion and precise digital temperature control; lower heat output ceiling than gas. |
| Non-heated | Mild climates and processes that do not need tempered air | Supplies fresh, filtered outside air. Heat can be added on request. |
A spray booth exhausts a large volume of air to carry overspray and solvent vapor outside. The air make-up unit (AMU) brings the same volume of fresh, filtered air back in. Without it the building goes negative: doors are hard to open, dust and dirt are pulled in through every gap, the booth starves for air and the finish suffers.
The AMU is sized to the booth exhaust in cubic feet per minute (CFM). Booth CFM comes from the booth airflow area and the design air velocity, so a larger booth or a downdraft booth with a full ceiling plenum needs more air. Most booths are balanced slightly positive so clean supply air, not shop air, fills the booth. See our air make-up unit guide for the details.
If the booth runs in cold weather, or the coating needs a stable temperature to flow out and flash, choose heated AMUs. Heating capacity is set by airflow and temperature rise: BTU/h is about 1.08 × CFM × the rise from the coldest outdoor temperature to your setpoint. In mild climates, non-heated AMUs supply fresh outside air at ambient temperature.
Direct-fired gas units put the burner in the airstream, so nearly all the heat goes into the supply air. Indirect-fired units heat the air through a heat exchanger, so combustion products never enter the booth. The choice depends on the application, local code and the fuel available.
Paired with the booth control panel, a heated AMU can run separate spray, flash and cure temperatures. That is how heated paint booths shorten cure cycles and keep production moving through the winter.
OSHA and NFPA 33 require replacement air for spray booths, and the AMU is interlocked with the booth exhaust so spraying cannot start without ventilation. Gas-fired units also need the gas train, flame safeguard and permits your jurisdiction requires. See our NFPA 33 guide.
In most cases, yes. A booth exhausts thousands of cubic feet of air every minute, and OSHA and NFPA 33 require that air to be replaced. An AMU does that with filtered air, keeps the building from going negative and keeps the booth airflow steady.
By the booth exhaust CFM, and for heated units by the temperature rise from your coldest outdoor design temperature to the booth setpoint. Send us the booth size and type and your location and we will size it.
Heated if the booth runs in cold weather or the coating needs a controlled temperature. Non-heated where the climate is mild and tempered air is not needed. A non-heated unit can be ordered with heat added.
Natural gas, propane and electric. Gas units are available as direct-fired or indirect-fired.
Usually. We check the booth exhaust CFM, the duct path and the controls, then size the AMU and interlock it with the existing exhaust fan.
