Give the supplier a heat-load brief, not just a body volume
Cubic volume is only one input to refrigeration selection. Heat enters through body surfaces and thermal bridges, through doors and seals, and through any cargo loaded above its required condition. State whether the task is to maintain pre-cooled cargo or perform a defined pull-down.
Available cooling output also changes with box and ambient conditions. A nominal model rating measured under different conditions cannot be used as a like-for-like selection value. Ask the supplier to expose the assumptions and margin in its calculation.
Compare heat load and cooling output at the same conditions
An oversized unit does not correct blocked return air or poor sealing; an undersized one can leave recovery too slow for the route. Door opening duration and multi-drop operation need explicit treatment rather than being hidden in a body-size rule.
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| Decision | What to establish | Condition or limit |
|---|---|---|
| Transmission | Calculate heat through body surfaces and thermal bridges. | Nominal panel thickness alone is incomplete. |
| Infiltration | Model doors, seals and opening duration. | Urban multi-drop duty can dominate the load. |
| Product load | State starting temperature and any pull-down requirement. | Holding pre-cooled cargo differs from cooling warm cargo. |
| Capacity basis | Compare unit output at project box and ambient conditions. | Headline ratings at different conditions are not comparable. |
Add the heat loads at the required operating conditions
Add the documented heat loads before comparing refrigeration units. Body volume and a model rating alone cannot establish the required capacity.
The example base load is 4.6 kW. It is not a unit selection until the supplier verifies every input, margin and capacity condition.
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| Step | Calculation or condition | Result |
|---|---|---|
| Base design load | 2.1 + 1.4 + 0.8 + 0.3 | 4.6 kW |
| Explained margin | 4.6 kW + documented uncertainty or recovery allowance | Supplier defines and explains |
| Capacity comparison | Unit capacity at project box and ambient conditions ≥ design load | Must pass |
- Transmission load: 2.1 kW
- Door infiltration load: 1.4 kW
- Product and internal loads: 0.8 + 0.3 kW
Illustrative heat-load components only. Use controlled thermal data, route conditions and refrigeration manufacturer performance tables.
Compare the unit model and local service, not just the badge
For Thermo King, Carrier or a proposed Chinese-brand unit, request capacity data at the same box and ambient temperatures, power requirements, dimensions, mass and control options. Make sure the quote identifies the exact model and installation scope. There is no like-for-like efficiency or reliability ranking without those records.
Ask who can service that model near your route, which parts they hold and how a warranty claim reaches the responsible supplier. Verify the provider and coverage before purchase. A manufacturer’s international network does not mean every location supports every export model, nor does it establish KEEYAK’s own local coverage.
Match the unit data to the acceptance test
Thermo King selection guidance applies to identified units under stated conditions. Use data for the proposed model and compare those conditions with the required route. A unit name or an empty-box temperature cannot establish its performance with a loaded body. Thermo King truck quick reference guide
Specify the ambient condition and cargo acceptance band, including the initial cargo and box temperatures. Record the insulation and door condition, load arrangement and door-opening schedule. Agree sensor locations and calibration, then state the power mode and recording interval. Keep the raw time-stamped results and exceptions; the proposed protocol is not a completed KEEYAK test.
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| Condition | Record | Interpretation |
|---|---|---|
| Pull-down | Initial box temperature, ambient, power mode and empty or loaded state | Do not equate empty-box cooling with cooling warm cargo. |
| Delivery operation | Cargo, airflow paths, door events and route duration | Review all probes and excursions against agreed criteria. |
| Model identity | Unit, body, insulation and software or control settings | A result for another model or body is contextual evidence only. |
Check cooling capacity in every power mode used on the route
Give the unit supplier a schedule that pairs each temperature zone and operating condition with its available power. Include the demanding ambient condition and repeated door openings, then identify what powers refrigeration during loading, driving and delivery stops. A capacity selection is incomplete if the required output is unavailable in a power mode the route depends on.
Thermo King's e200 sheet describes electric refrigeration for electric or engine-powered vehicles and lists separate power-supply requirements. This is an example of why electric refrigeration does not, by itself, identify the truck drivetrain or prove cooling endurance while parked. Thermo King e200 specification sheet
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| Route period | Buyer input | Supplier confirmation |
|---|---|---|
| Loading at base | Zone temperatures, cargo starting condition, loading duration and available external supply | Required cooling duty and compatibility with the actual site supply |
| Driving and repeated stops | Ambient conditions, zone loads, door events and permitted engine operation | Available refrigeration output in each intended operating mode |
| Parked holding | Required holding time and power source; battery reserve if applicable | Usable energy, controls and limits for the agreed condition |
Request a selection record for the complete body and route
Supply the thermal body data, ambient and cargo conditions, door schedule and required power modes. Keep the unit’s controlled capacity data with the supplier calculation and acceptance plan. Model names and brand comparisons become useful only after those conditions match.
Information to prepare for this review
- Internal and external body dimensions
- Insulation material, thickness and thermal data
- Required box and worst ambient temperatures
- Cargo mass, starting temperature and pull-down responsibility
- Door sizes, openings and route pattern
- Airflow, power, defrost and monitoring requirements
Records to request and keep
- Approved body and operating brief
- Supplier heat-load calculation with assumptions
- Capacity data at project conditions
- Installation, commissioning and airflow verification
Common mistakes and what to check instead
- Sizing from cubic volume only: Calculate all material heat-load components.
- Comparing nominal unit model numbers: Compare capacity at the same box and ambient conditions.
- Adding an unexplained safety factor: State the uncertainty or operational reason for the margin.
Scope of this guide
This page does not perform the final heat-load calculation.
Thermal properties and unit capacity data must come from controlled supplier documents.
Do not approve a unit without a matched body, operating brief and capacity basis.
Sources and applicability
Manufacturer selection reference for the listed Thermo King units and stated body and operating assumptions; not proof for another unit.
Sources checked:
Named-unit example of electric refrigeration on electric or engine-powered vehicles, with separate supply requirements. It is not a KEEYAK component offer, capacity or endurance claim.
Pages 1–2, power options and alternator guidelines
Sources checked:
Controls the project-input, quotation, approval and inspection workflow described in this guide.
Provides public checklists and worksheets; the signed project documents remain controlling.
Defines the relevant product family and published configuration boundaries. Project-specific ratings require the selected OEM documents.
Primary public guidance supporting preconditioning, airflow, door-seal and loading checks. Cargo-owner and destination requirements remain controlling.