The size calculator estimates storage space, not refrigeration capacity.
In short: calculate transmission, door infiltration, product load and internal heat, then select the unit at the actual design conditions.
An undersized unit may never recover after deliveries. A badly oversized fixed-capacity unit may run very short cycles. Both can result from choosing by room volume alone.
Include ambient temperature, product entry temperature, door traffic, defrost, people, lights and equipment. Compare catalogue capacity at the required evaporating and condensing conditions.
Do not stack several unexplained safety margins. State each assumption and have the final selection checked.
Why volume-only sizing fails
| Sizing error | What happens | Long-term result |
|---|---|---|
| Under-sized | Unit runs continuously, never pulls down to setpoint | Early compressor failure; product at risk |
| Over-sized | Unit short-cycles, swings temperature | Wasted energy; poor humidity control; wear |
Room volume is only one input. Two rooms of identical volume can have very different loads depending on door traffic, product turnover, ambient temperature, and internal heat sources.
Calculate the full heat load
Add up every source of heat the unit must remove:
- Transmission — heat conducted through the panels (driven by panel thickness and the ambient-to-setpoint difference).
- Infiltration — warm, humid air drawn in through door openings.
- Product (pull-down) load — the energy to cool incoming product and, for freezers, the latent heat of freezing.
- Internal sources — fans, lighting, people working inside.
Match a unit to that total, not to a volume rule of thumb. Use the Frostbox size calculator or the method in Heat load calculation.
Matching the Daikin family
The Frostbox catalogue pairs rooms with Daikin condensing-unit families. The correct family depends on capacity, temperature class, and whether the installation is quick-connect or standard split:
| Use case | Daikin families |
|---|---|
| Compact rooms, quick-connect split (pre-charged line sets 2.5 / 5 / 10 m — self-install, no F-gas certification required) | GS, SP-O |
| Larger installations or longer runs, standard split (installed by a certified technician) | DB-O, SAR, SAS |
Refrigerant choice is version- and market-dependent — confirm the specific datasheet for any quoted unit rather than assuming a blanket value.
Frostbox standard range: Panel choice feeds directly into heat load. The Frostbox/Algor line is 80 mm and 100 mm for chill/cold rooms and 100 mm and 120 mm for freezing rooms; the without-floor option exists only for the Cold Room 80 mm configuration. Specify the panel for the temperature first, then size the unit to the resulting load.
Related articles
- Common installation mistakes: overview
- Structural assembly mistakes (floor, panels, plumb, cam-locks)
- Door, sealing & commissioning mistakes
- Using the Frostbox size calculator
- Heat load calculation
- Refrigeration system selection
Guidance reflects the MTH Algor cam-lock panel system supplied by Frostbox. For a heat-load review, contact [email protected].
