Hidden fridge quotes describe layouts that put the visible parts of the unit behind a panel or in the roof void; details vary between suppliers, so the drawing should show what goes where. The layout does not change the insulation requirement, because target temperature sets the wall thickness. Under ATP 2024, Annex 1, a normally insulated (IN) body can have a K coefficient of up to 0.70 W/m²·°C; heavily insulated (IR) bodies are limited to 0.40, and classes B, C, E and F, which can reach -10 °C or below, must in every case stay at or below 0.40. Chilled and frozen goods therefore do not travel behind the same wall.
Thickness is paid for in interior volume. A hypothetical example: for a body with external dimensions of 3.30 × 1.80 × 1.85 m (10.99 m³), insulated to the same thickness on all six faces, the remaining volume changes as follows.
| Insulation thickness | Interior (m) | Interior volume |
|---|---|---|
| 40 mm | 3.22 × 1.72 × 1.77 | 9.80 m³ |
| 60 mm | 3.18 × 1.68 × 1.73 | 9.24 m³ |
| 80 mm | 3.14 × 1.64 × 1.69 | 8.70 m³ |
Going from forty to eighty millimetres takes away 1.10 m³. That calculation leaves out the liner, shelves, air ducts, threshold and door seal, each of which reduces the door opening and stack height further. A quote should therefore list the external size, the finished internal size and the narrowest clear door opening on separate lines.
A hidden layout can cut the projection above the load, but the evaporator's airflow path still cannot be blocked. A Thermo King trailer-unit manual (pp. 125-126) asks for pre-cooled cargo, space for air circulation around the load and evaporator inlets and outlets left open; the unit is designed to hold temperature, not to pull down a warm load. Take another installation's clearances from its own documentation.
Service access is written down in two parts: where the service panel opens for daily checks, and whether workshop maintenance needs a panel removed or the vehicle unloaded. If the last row of containers blocks the service panel, the layout does not fit the workflow. Compare two layouts on the same loading job: one may fit an extra container, the other keeps the evaporator and service access clear.
If an insulated container such as GEBHARDT Isotec TBX is going into the vehicle, its external size and the door opening are checked separately. Tie the load and entry checks to the same drawing, as in the refrigerated-body dimensions guide.
