You have two cooling rooms and a room for freezing storage. You received an offer with a condenser unit for each room, another offer with a central rack, and a third offer with a glycol chiller. Before comparing prices, ask each supplier how each room will receive its required capacity on loading day, and what will remain operational if part of the system stops? The answers to these two questions clarify differences that the total kilowatts in the price offer may conceal.
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1. Independent condenser unit for each room
In this arrangement, each room has its own condenser, evaporator, and refrigerant circuit. If the freezing room unit stops, the cooling rooms can continue as long as the fault is confined to the room's circuit, and there is no shared fault in the electrical supply or control. You can also add a new room with an independent circuit when the project expands.
The trade-off is that each room needs its unit and space for installation, ventilation, and maintenance. As the number of rooms increases, compare the cost of repeating units and maintenance points with the cost of the central system. If you have one room with high inventory value, review its emergency plan even if the other rooms are independent.
2. Central compressor rack
The rack combines several compressors serving a group of evaporators. When the load decreases, the control system can operate fewer compressors or adjust the capacity according to the design. This idea is useful in a facility where room loads change throughout the day, especially if receiving and loading times differ.
The temperature of each group matters. Cooling rooms and freezing rooms often require different evaporation temperatures. If the offer combines them on one rack, request a diagram showing the pull groups or the method of separating the two levels, and the capacity of each group under its conditions. Operating cooling loads at a suction pressure lower than required may increase energy consumption, depending on the system design.
Having more than one compressor makes you ask about the remaining capacity. If a compressor goes out of service, how many kilowatts will remain available for each group? And if the fault is in a common component like the control panel or the condenser, which rooms will be affected? The answer to this question determines whether the system can maintain the critical rooms during maintenance.
3. Chiller with water or glycol circuit
In this system, the chiller cools a fluid, and the pumps distribute it to heat exchangers in the rooms or production lines. This is an option worth considering when the project itself requires cooling fluid to serve more than one point, such as refrigerated storage rooms and a production line, and you want to consolidate the main refrigerant circuit in the equipment area.
In comparison, calculate the consumption of the pumps alongside the chiller consumption, and check the fluid temperature at supply and return, pipe insulation, and glycol properties at the operating temperature. The lower the application requires temperatures, the more important the choice of fluid, pump, and exchanger becomes. If the offer includes a freezing room, request to calculate the circuit performance at the required operating temperature for the room.
A practical example for a project with 3 rooms
Assume you have two cooling rooms at +2°C and a frozen storage room at −18°C. After calculating the loads, the first cooling room needs 8 kilowatts, the second 7 kilowatts, and the freezing room 10 kilowatts. These numbers are hypothetical, and the room temperatures differ from the refrigerant evaporation temperatures used in the selection.
| If the offer includes | ask the supplier to clarify |
|---|---|
| 3 independent units | the capacity of each unit under its room conditions, and the installation, ventilation, and maintenance location. |
| Central rack | the capacity of the cooling group and the freezing group separately, and the remaining capacity when the largest compressor goes out of service. |
| Glycol chiller | The fluid temperature and flow rate at each load point, the pump power requirements, and how the system will achieve the required freezer room temperature. |
If the two cooling rooms receive shipments at the same time, the proposal must show how the system will cover the simultaneous load. If the receipt is at different times, the designer may study the impact of this on the capacity of the cooling unit, based on an actual operating schedule. The capacity of the freezing unit is preferably calculated under its specific conditions. .
Before you approve the price quote
ask each supplier to provide the same data so that the comparison is based on a single standard.
- Room load schedule in kilowatts, with the product temperature upon entry, its quantity, and loading times.
- Cooling capacity under design conditions for each room or unit, specifying operating temperatures and refrigerant.
- The electrical capacity of the entire system, including fans and pumps as per design, and operating data at partial load if available.
- Failure and maintenance scenario, detailing the rooms that will be affected and the capacity that will remain available.
- Supply limits, including pipes, insulation, control, installation, and operation, so you can compare the cost of the same scope of work.
Are you preparing a project with more than one room? Send to the team
Al-Bassem refrigeration industries the required storage temperatures, daily product quantities, loading times, and specify the rooms that must remain operational during maintenance.