1. Design and load calculation
Before anything is built, the designer works out the refrigeration load: room size and temperature, how much product enters each day and at what temperature, how often the door opens, lighting, people working inside and the ambient temperature around the room and condensing unit. In Indian conditions the design ambient matters a great deal; a condensing unit sized for a mild climate will struggle on a terrace in May.
The result decides the evaporator and condensing unit size, the panel thickness and whether the supply needs to be single-phase or three-phase.
2. Site, floor and services
- Level, load-bearing floor; freezer rooms need an insulated floor with a vapour barrier and protection against frost heave.
- A planned position and route for the condensing unit, piping and electrical cables.
- Power supply to a lockable isolator, installed by a licensed electrician.
- A drain point for the evaporator condensate, with a trap and the right fall.
- Clear access for panels, which arrive as large flat sheets.
3. Erecting the insulated panels
Panels are usually polyurethane (PUF) or polyisocyanurate (PIR) foam sandwiched between coated steel sheets, joined with cam locks or tongue-and-groove joints. Walls go up first on a floor channel or the floor panels, then the ceiling. Large rooms need ceiling hangers or a supporting structure.
Every joint is sealed with a suitable sealant. Gaps let warm, humid air into the panel joints, where moisture condenses and freezes, pushing joints apart over time. A tidy, continuous seal line is one of the best signs of a careful installer.
4. Fitting the door
The door must close and seal reliably. Freezer room doors normally have a heated frame so the gasket does not freeze to it, and a pressure relief valve in the wall so the door can be opened after warm air inside has cooled and contracted. Every walk-in door should open from the inside without a key, and many installations add an inside alarm button for anyone accidentally shut in. Strip curtains or an air curtain reduce warm air entry during busy loading.
5. Evaporator, condensing unit and piping
The evaporator is hung from the ceiling so its fans throw air along the room without blowing straight at the door. The condensing unit goes where it gets plenty of fresh air and shade. Copper refrigerant pipes connect the two, sized and routed so oil returns to the compressor.
Good practice is to braze joints with dry nitrogen flowing through the pipe to prevent internal oxide scale, pressure-test the system with nitrogen to find leaks, then pull a deep vacuum to remove air and moisture before charging refrigerant. Skipping the vacuum or the pressure test saves an hour and can cost the compressor.
6. Electrical work and controls
The control panel connects the compressor, fans, defrost heaters (in freezer rooms), door heaters and lighting. Phase protection, overloads and a temperature controller with alarm are standard. All of this is licensed electrician's and refrigeration technician's work. Ask for the control settings — setpoint, defrost interval and alarm limits — to be written down and handed over.
7. Condensate drain
The evaporator drip tray drains through a pipe that leaves the room, falls continuously and ends in a trap. In freezer rooms the drain line inside the room needs a heater so defrost water does not freeze in the pipe and back up into the tray.
8. Commissioning and handover
- Check pressures, superheat and current draw against design.
- Pull the room down to temperature empty and confirm it holds through a defrost cycle.
- For freezer rooms, many installers pull down in stages rather than all at once to reduce stress on panels and joints; follow your contractor's procedure.
- Test alarms, door heaters, inside release and lights.
- Receive as-built drawings, settings, test records and the maintenance schedule.
Frequently asked questions
- Can I load the cold room on the day it is commissioned?
- Only once it has reached and held its set temperature empty, including through a defrost. Load gradually and avoid filling it with large amounts of warm product at once.
- Do cold rooms need fire approval?
- It depends on the building, its size and use, and your state's rules. Insulated panels add fire load, so check with your architect and the local fire authority early.