## Common ground
All options refer to heat exchangers—devices that transfer heat between two or more fluids without mixing them.
## Options at a glance
**7322.90 – Air heater exchangers**
- **Defining trait:** Designed specifically for heating air, often in industrial or HVAC systems.
- **Typical examples:** Radiant tube heaters, air preheaters in furnaces.
- **Best fit when:** Used to heat air directly, not fluids like water or refrigerants.
**8402.90 – Boiler/steamer exchangers**
- **Defining trait:** Integrated into hot water boilers or steamers for heating water via combustion.
- **Typical examples:** Firebox heat exchangers in boilers, steam generator tubes.
- **Best fit when:** Part of a system that generates hot water or steam using fuel.
**8415.83 – AC heat exchangers**
- **Defining trait:** Used in air conditioning systems to transfer heat between refrigerant and air.
- **Typical examples:** Evaporator coils in indoor AC units, condenser coils.
- **Best fit when:** Part of a cooling system using refrigerants.
**8418.99 – Refrigeration exchangers**
- **Defining trait:** Designed for heat transfer in refrigerating or freezing equipment (e.g., cold rooms).
- **Typical examples:** Evaporators in freezers, condensers in chillers.
- **Best fit when:** Cooling applications with low-temperature refrigerants.
**8419.50 – Exchange units (brazed/aluminum/coolers)**
- **Defining trait:** Compact, often modular units like brazed aluminum plate-fin or CPU coolers.
- **Typical examples:** Laptop cooling systems, automotive radiator cores.
- **Best fit when:** High-efficiency, small-scale heat transfer in electronics or vehicles.
**8419.89 – Water-tube type**
- **Defining trait:** Fluid flows through tubes surrounded by another fluid (e.g., steam).
- **Typical examples:** Boiler tubes, industrial process heaters.
- **Best fit when:** High-pressure or high-temperature water/steam systems.
**8419.90 – Fire-tube type**
- **Defining trait:** Hot gases flow through tubes surrounded by water (common in boilers).
- **Typical examples:** Traditional steam boilers, marine boilers.
- **Best fit when:** Combustion gases heat water via internal tubes.
**8476.90 – Vending machine exchangers**
- **Defining trait:** Used specifically in vending machines for cooling or heating products.
- **Typical examples:** Beverage cooler coils, heated trays in snack machines.
- **Best fit when:** Integrated into vending equipment for temperature control.
## Key differences
| Option | Primary Fluid | Main Use Case | Flow Design | Integration |
|-------|----------------|----------------|--------------|--------------|
| 7322.90 | Air | Heating air | Air-side only | Standalone or HVAC |
| 8402.90 | Water/steam | Boiler/steamer | Internal heating | Embedded in boiler |
| 8415.83 | Refrigerant/air | Cooling (AC) | Refrigerant cycle | AC systems |
| 8418.99 | Refrigerant | Freezing/refrigeration | Low-temp cooling | Chillers, freezers |
| 8419.50 | Any | Electronics/vehicles | Compact plate-fin | CPU, car radiators |
| 8419.89 | Water/steam | High-pressure systems | Water inside tubes | Industrial boilers |
| 8419.90 | Gases/water | Steam generation | Gases in tubes | Traditional boilers |
| 8476.90 | Refrigerant/air | Vending machines | Small-scale | Dedicated equipment |
## How to choose
- Is it used for heating air? → 7322.90
- Is it part of a boiler or steamer? → 8402.90
- Is it in an air conditioning system? → 8415.83
- Is it for refrigeration/freezing? → 8418.99
- Is it a compact unit (e.g., CPU cooler, aluminum plate)? → 8419.50
- Does water flow through tubes surrounded by gas/steam? → 8419.89
- Do hot gases flow through tubes surrounded by water? → 8419.90
- Is it in a vending machine? → 8476.90
## Overlaps & pitfalls
- A heat exchanger in a boiler may fit both 8402.90 and 8419.89/90 depending on design.
- AC and refrigeration units can overlap (e.g., same coil type), but use differs: cooling vs. freezing.
- If multiple functions apply, prioritize the **main purpose**—e.g., if it cools drinks in a vending machine, use 8476.90 even if it uses refrigerant.
- Avoid confusion: “heat exchanger” is general; the HS code depends on **application and system integration**