Cast Air Heavy Duty Shop Tandem Air Compressor — T20324HC3-S
The T20324HC3-S is the top configuration in the 20 HP Shop Tandem series: two 20 HP motors driving HC3 cast iron pumps at 570 RPM on a 240-gallon horizontal ASME tank. Combined output is 180 CFM at 0 PSI and 140 CFM at 175 PSI. At $11,610, this is a serious machine for serious shops. The HC3 pump at 570 RPM is the slowest, quietest, longest-lived pump option Cast Air makes for this horsepower range. Paired with the 240-gallon receiver, you get maximum pressure stability and maximum pump longevity in a single unit. If your shop runs a compressor hard all day, every day, and you cannot afford pump rebuilds every few years, this is the configuration that makes sense economically over a 10–15 year service life.
What Justifies $11,610?
- 570 RPM HC3 pump: The HC3 runs 25% slower than the HC2. At sustained compressor duty, that RPM reduction translates directly to longer valve life, lower operating temperatures, reduced vibration, and extended intervals between major pump service. A pump rebuild on a heavily loaded compressor might come every 4,000 hours on an HC2 — the HC3 pushes that interval substantially longer.
- 240-gallon receiver: Double the storage of the 120-gallon configuration. At 140 CFM of pump output and 240 gallons of storage, this machine handles production-level demand spikes without pressure instability.
- Dual redundancy: Two independent pump systems mean one side can go down for service while the other keeps the shop running. A $11,610 machine that never stops the shop is worth more than an $8,000 machine that stops it once a year for a pump rebuild.
Cast Iron Pump Features
- All cast iron construction: Cylinders, heads, and crankcase on both pumps. The HC3 is the largest pump in the Cast Air industrial piston series.
- 570 RPM (HC3 configuration): The slowest pump speed in the Shop Tandem lineup. Minimal heat generation, minimal vibration, maximum longevity.
- Tapered roller bearings: Both ends of each crankshaft. Built for decades of sustained operation.
- Precision steel connecting rods: Automotive-type rod insert bearings at the crank, needle bearings at the wrist pin.
- Disc and spring valves: Field-serviceable, easy to inspect and rebuild. At 570 RPM, valve wear rates are substantially lower than faster pumps under identical load.
- 4-ring pistons: Maximum efficiency, minimal oil carry-over.
- Centrifugal unloader: Loadless start every cycle. With 40 HP total, eliminating hard-start stress is essential for motor and contactor longevity.
Tank and Controls
- 240-gallon horizontal ASME tank: Powder-coated, channel base. At this horsepower level and pump output, the 240-gallon tank provides the buffer that keeps system pressure stable under any realistic shop demand pattern.
- Two magnetic motor starters — mounted and wired: Factory-installed on both pump sides. Ready to connect to 3-phase service.
- ASME safety valves: Factory-set on both sides.
- Metal belt guards: Fully enclosed on both pump assemblies.
- Copper discharge and unloader tubes: Copper throughout the hot side of both assemblies.
- 1,725 RPM industrial motors: Full 15% service factor or higher on both 20 HP motors.
Available Factory-Mounted Options
- Low Oil Control (#6304x2M): Automatic oil-level shutdown on both pumps. Non-negotiable for production environments.
- Hour Meter 230V (#HRM75x2M) or 460V (#HRM460x2M): Track runtime independently on each pump for scheduled maintenance.
- Alternator Relay (#ALT230M or #ALT460M): Automatically alternates lead pump each cycle to equalize wear on both sides.
- Electronic Auto Drain (#SDV03M): Timed solenoid condensate drain. Critical on a 240-gallon tank in high-humidity environments.
- Dual Control (#DC2x2M): Start/stop and throttle control modes. Standard on HC3 configurations — confirm at order.
- Aftercooler (#BGAC1x2M, 70 CFM rated per unit): Belt-guard-mounted aftercooler on both pump sides. Highly recommended for compressed air quality in a production environment.
- All Options Package (#AOC3D): All asterisk options at 10% off. Note: Cannot combine intake silencers and dual control on HC3 units.
What Is in the Box
- Two cast iron two-stage HC3 pump and motor assemblies (20 HP each) on a single rigid frame
- 240-gallon horizontal powder-coated ASME tank with channel base
- Two magnetic motor starters, mounted and wired at the factory
- Two ASME safety valves
- Two metal belt guards (fully enclosed)
- Copper discharge and unloader tubes on both sides
- Pressure switch for each pump
Optional accessories are factory-installed at time of order and are not included unless specified at purchase.
Available Configurations — 20 HP Shop Tandem Lineup
- T20312HC2-S: 2×20 HP, 758 RPM, 180 CFM / 140 CFM @ 175 PSI, 120-gal — $7,974
- T20312HC3-S: 2×20 HP, 570 RPM, 180 CFM / 140 CFM @ 175 PSI, 120-gal — $10,285
- T20324HC2-S: 2×20 HP, 758 RPM, 180 CFM / 140 CFM @ 175 PSI, 240-gal — $9,460
- T20324HC3-S: 2×20 HP, 570 RPM, 180 CFM / 140 CFM @ 175 PSI, 240-gal — $11,610 (this unit)
When Does a Shop Need This vs. Stepping Up or Down?
- Step down if duty cycle is lower: If your shop does not run the compressor all day, the T20324HC2-S at $9,460 delivers identical CFM and storage for $2,150 less. The HC3 premium is justified by longevity — but only if you actually run the machine hard enough to see the difference.
- This unit is right when: Your compressor runs 8–12 hours per day, you cannot tolerate the downtime of frequent pump service, and you want the longest service intervals available in the 20 HP piston tandem class. Production shops, large collision centers, fleet maintenance facilities, and manufacturing plants with sustained air demands are the right home for the T20324HC3-S.
- Step up to 25–30 HP tandem: If 140 CFM is not enough — very large shops or high-demand production operations — the T25324HC2-S or T30324HC3-S deliver up to 210 CFM at 175 PSI on the same general platform.
Technical Specifications — T20324HC3-S
- Model Number: T20324HC3-S
- Horsepower: 2 × 20 HP (40 HP total)
- Phase: 3-phase
- Pump RPM: 570 (HC3 configuration)
- CFM @ 0 PSI: 180 (combined, both pumps)
- CFM @ 175 PSI: 140 (combined, both pumps)
- Tank Capacity: 240 gallons, horizontal
- Tank Type: ASME-certified, powder-coated, channel base
- Motor Speed: 1,725 RPM, 15% service factor
- Pump Type: Two-stage, all cast iron, centrifugal unloader
- Controls: Two magnetic motor starters, mounted and wired; Dual Control standard on HC3
- Discharge Tubing: Copper
- Belt Guard: Metal, fully enclosed
- Price: $11,609.90
Note: Exact LxWxH dimensions and shipping weight for this configuration are not individually published by Castair. Contact us for freight details before ordering.
Why Buy From Air Compressor Factory Direct?
We have specialized in industrial air compressor sales since 2016. At the $11,000+ price point, you should be confident this is the right machine before you buy it. We will help you evaluate whether the HC3 premium is justified by your duty cycle, and whether 240 gallons of storage is actually what your demand pattern requires.
- Free shipping to a commercial address with a loading dock or forklift
- Free tech support at 866-217-0063 — honest assessment before you spend this kind of money
- Full Cast Air manufacturer warranty — handled directly through us
- Honest guidance: If you would be equally well served by the HC2 or a smaller tandem, we will tell you. We would rather you buy the right machine once.
Call 866-217-0063 for quick answers and help!
