Product Name: How to Build a Small Cold Room

Small cold rooms (typically 10–50m³, used for restaurant kitchens, fresh food stores, pharmacies, or farm produce storage) are popular due to their low cost, quick construction, and flexible mobility. For hands-on users, mastering a standard small cold room construction method not only saves installation costs but also allows better control over insulation and refrigeration details. Below are the detailed steps for building a small cold room from scratch.

I. Preliminary Planning and Site Selection

The first step in building a cold room is to determine your requirements:

Temperature zone: Chiller room (0–5°C) or freezer room (below -18°C)?

Dimension measurement: Based on the volume of items to be stored, reserve 20%–30% extra space.

Site requirements: Choose a location with good ventilation, no direct sunlight, a level floor, and sufficient load-bearing capacity. For outdoor installation, build a sunshade and rain shelter to protect the unit from sun and rain.

II. Material Preparation and Selection

Core materials for building a cold room include:

1. Insulated panels: Polyurethane sandwich panels (PU panels) are recommended, with a density of ≥40kg/m³. For chiller rooms, choose 100mm thickness; for freezer rooms, choose 120mm–150mm. The thickness of the color steel on both sides should be ≥0.376mm.

2. Refrigeration unit: Select based on the horsepower calculation method mentioned earlier (e.g., a 10m³ freezer room requires a 3HP hermetic scroll unit).

3. Evaporator: Match with an air cooler (forced air) or aluminum fin coils (for humidity retention).

4. Auxiliary materials: Cold room door (with lock and emergency release), sealant (neutral silicone weather-resistant), waterproof tape, copper pipes (deoxidized phosphorus copper), insulation foam, refrigerant (R404A/R22).

III. Detailed Construction Steps

1. Panel Assembly

Floor leveling: Lay a moisture barrier (e.g., PE film), then install the floor panels.

Wall panel assembly: Assemble wall panels in order, lock them together with eccentric hooks, and apply sealant at the joints to ensure an airtight seal.

Ceiling installation: Install the ceiling panels safely, reinforcing the lifting points.

Door installation: Install the cold room door, adjust the lock and gasket to ensure a tight seal with no cold air leakage.

2. Refrigeration System Installation

Unit placement: Position the unit in a well-ventilated area, and add anti-vibration pads under the base.

Copper pipe connection: Cut copper pipes to the designed length, avoiding excessive bending. Use nitrogen-assisted welding to prevent oxidation scale from clogging the system.

Electrical wiring: Connect the power wires for the compressor, condenser fan, evaporator fan, and temperature controller according to the wiring diagram, ensuring proper grounding.

Evacuation and leak check: Use a vacuum pump to evacuate the system to below -0.1MPa, and hold for 24 hours without pressure rise to pass.

3. Insulation and Sealing

Pipe insulation: Wrap all copper pipes and joints with insulation foam, and secure with tape.

Gap treatment: Fill gaps between the cold room panels and walls/floors with foam, and apply sealant on the outside for waterproofing.

4. Commissioning and Operation

Power-on test: Connect power, check that the unit rotates in the correct direction and makes no abnormal noise.

Temperature setting: Set the target temperature (e.g., -18°C) and observe the cooling curve.

Defrost test: Check that the automatic defrost function works properly and the drain line is clear.

IV. Common Problems and Solutions

Slow cooling or no cooling: Often due to refrigerant leakage or insufficient charge; may also be caused by poor heat dissipation (dirty condenser or fan failure).

Excessive frost: Could be a faulty defrost timer on the evaporator fan or a damaged defrost heating element.

Excessive noise: Check if the anti-vibration pads on the unit base are worn, or if copper pipes are resonating with the wall.

Water dripping inside: Check if the drain pipe slope is sufficient, or if insulation is damaged causing "sweating".

V. Summary

The key to building your own small cold room is "perfect sealing" — the insulation panels must be joined tightly, copper pipes welded securely, and sealant applied thoroughly. As long as you strictly follow the steps above, especially the two core processes of nitrogen-assisted welding and vacuum evacuation, even a DIY small cold room can achieve commercial-grade cooling performance and energy efficiency. For beginners without electrical or welding experience, it is recommended to hire professionals to handle the connection and commissioning of the refrigeration system to ensure safety and quality.

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