The Castair Aftercooler Option Bundle AOC1D is the duplex, 230-volt single-phase version of Cast Air's factory aftercooler options package. A duplex compressor installation runs two compressor units — typically on a shared receiver tank with an alternator relay that staggers their operation, so one runs lead and the other runs lag, switching off over time to equalize wear. The aftercooler for a duplex system has to be sized and configured for the combined discharge from both compressors — using a simplex aftercooler bundle (AOC1) on a duplex installation means the heat exchanger is undersized for actual airflow at peak demand, which degrades performance exactly when you need it most. The AOC1D is built for this configuration.
Like all Castair aftercoolers, the AOC1D cools compressed air discharge to within 15°F of ambient temperature before it enters the receiver tank. At full cooling, approximately 65% of the water vapor in the compressed air condenses and drains out at the aftercooler — not in the tank, not in the piping, and not in your tools or spray equipment. For a duplex system running at the kind of sustained duty cycle that justifies two compressors, this moisture removal at the source is essential to keeping downstream equipment working correctly.
Duplex Compressor Systems: Why Configuration-Matched Aftercooling Matters
A duplex system is not just two compressors sitting next to each other — it is a coordinated system where both machines share a common discharge header and tank. When both compressors are running simultaneously (which happens during high-demand periods), the combined discharge volume into the aftercooler is the sum of both machines' output. If the aftercooler is sized for one compressor, it is receiving twice the airflow it was designed for. The result:
- Insufficient residence time in the heat exchanger: Air moves through too quickly for the fan to cool it to near-ambient temperature
- Higher outlet temperature: Air exits the aftercooler warmer than it should, carrying more moisture than a properly sized unit would remove
- Downstream effects: The refrigerated dryer receives hotter, wetter air than it was designed to handle, its performance degrades, and wet air continues downstream to tools and spray equipment
The AOC1D is matched to the duplex configuration — sized for the combined output of both compressor units, not just one.
Key Features of the AOC1D Bundle
- Duplex Configuration: Sized and specified by Castair for two-compressor installations — handles combined discharge volume from both units
- 230V Single-Phase: Matched to 230-volt, single-phase electrical service — check your compressor nameplates before ordering
- Factory-Matched Components: Aftercooler, fan, drain provisions, and hardware are factory-specified for Castair duplex compressor systems
- 250 PSIG Maximum Working Pressure: Compatible with the full operating pressure range of Castair industrial compressors
- 350°F Maximum Inlet Air Temperature: Handles the hottest discharge temperatures from two-stage reciprocating pumps
- Cools to Within 15°F of Ambient: Brings combined duplex discharge air down to near ambient temperature before the shared receiver tank
- 65% Total Moisture Removal: Removes approximately 65% of water vapor from the compressed air stream at the source — every 20-degree temperature drop removes 50% of remaining moisture
- Complete Package Ordering: One bundle covers the complete aftercooler installation for a duplex system — no need to source components separately
- Minnesota Manufacturing: Castair builds to industrial-grade standards in Minnesota
What Is Included in the AOC1D Bundle
The AOC1D is a factory options package. Components are matched to specific Castair duplex compressor configurations — contact us to confirm the exact contents for your compressor models before ordering.
Factory bundle packages typically include:
- Aftercooler heat exchanger: Sized for duplex system output, fan-cooled, 250 PSIG / 350°F rated
- Cooling fan and motor assembly: 115V, 1-phase, 60 Hz — runs on standard shop power
- Condensate drain provisions: For removing moisture collected at the aftercooler drain point
- Mounting and connection hardware: Factory-matched for the duplex compressor system
Optional accessories: filter with automatic drain, temperature control valve #86816.
AOC Bundle Configurations — Selecting the Right Version
Three versions of this factory aftercooler bundle cover different electrical service and compressor configurations:
- AOC1: 230V, single-phase, simplex — one compressor on standard single-phase service
- AOC1-460: 460V, three-phase, simplex — one compressor on industrial three-phase service
- AOC1D: 230V, single-phase, duplex — two compressors sharing a common tank on single-phase service (this bundle)
If you have a duplex system on 460V three-phase service, contact us — we can help identify the correct configuration for your installation.
Full Castair Free Standing Aftercooler Lineup (For Reference)
Castair's standalone free standing aftercoolers cover 35–300 CFM and are available for field installation on any compressor system:
- FSAC35: 35 CFM, 3/4 inch NPT
- FSAC50: 50 CFM, 1 inch NPT
- FSAC75: 75 CFM, 1 inch NPT
- FSAC100: 100 CFM, 1-1/4 inch NPT
- AC120: 120 CFM, 1-1/2 inch NPT
- AC150: 150 CFM, 1-1/2 inch NPT
- AC240: 240 CFM, 2 inch NPT
- AC300: 300 CFM, 2 inch NPT
When Does a Shop Need the AOC1D?
- You are running a Castair duplex compressor system on 230V service and want factory-integrated aftercooling — this is the bundle designed for that configuration
- You are ordering a new Castair duplex system and want the aftercooler specified and matched at the factory rather than adding components later
- You are retrofitting aftercooling to an existing Castair duplex installation on 230V service — the AOC1D gives you factory-matched components rather than a field-improvised assembly
- Your duplex system is producing wet air and you currently have no aftercooling or an undersized aftercooler — a properly sized duplex aftercooler at the discharge point is the correct fix
- Your refrigerated dryer is not keeping up on a duplex system — the combined thermal load from two compressors discharging into the system is often more than a dryer can handle without an aftercooler upstream to pre-cool the air
For single-compressor systems, order AOC1 (230V) or AOC1-460 (460V) depending on your electrical service.
Technical Specifications
- Model: AOC1D
- Manufacturer: Castair (Cast Air) — Minnesota, USA
- Bundle Type: Complete factory aftercooler options package
- Voltage: 230V
- Phase: Single-phase
- Compressor Configuration: Duplex (two-compressor system)
- Maximum Working Pressure: 250 PSIG
- Maximum Inlet Air Temperature: 350°F
- Approach Temperature: Within 15°F of ambient
- Water Removal: Approximately 65% of total moisture (at 250°F inlet)
- Fan Power: 115V, 1-phase, 60 Hz
- Category: Accessories — Aftercoolers
- Compatibility: Contact us to confirm matched Castair duplex compressor models
Why Buy From Air Compressor Factory Direct?
Air Compressor Factory Direct has been supplying commercial and industrial compressed air equipment since 2016. Duplex compressor systems are a more complex purchase than a single-unit installation — getting the aftercooler configuration right requires knowing your compressor models, combined CFM output, electrical service, and installation layout. When you call us about the AOC1D, we can work through all of those details with you before anything ships.
- Free Shipping: AOC1D bundles ship free to the continental US
- Free Pre-Sale Technical Support: Call us with your Castair duplex compressor model numbers and we will confirm the AOC1D is the correct bundle for your system
- Full Manufacturer Warranty: All Castair equipment and factory option bundles carry full factory warranty
- Honest Guidance: If your duplex system needs a different configuration, we will identify the right product before you order — not after it arrives
- Castair Specialist: We carry the complete Castair line and understand how the components work together
Call 866-217-0063 for quick answers and help!
