Using one condensing unit for multiple cold rooms means one outdoor condensing unit supplies refrigerant to two or more evaporators, usually one evaporator for each room, through a shared liquid line and a shared suction return.
This setup can lower equipment cost, save outdoor space, and simplify maintenance. Tuy nhiên, it only works well when the room temperatures, load conditions, piping design, and control logic all match the application.
The key idea is simple: each cold room must cool independently. One room should call for cooling, reach setpoint, and stop cooling without forcing the other rooms to overcool or lose control.
When This Design Makes Sense
A one-condensing-unit multi-room design works best when the cold rooms have similar temperatures and similar operating conditions.
Good Applications:
Same-Temperature Rooms: The Simplest Configuration
Same-temperature rooms create the simplest and most reliable one-to-many setup.
Ví dụ, if you have three cold rooms at +2°C, +3°C, and +4°C, one shared condensing unit often works well because the system can use a similar suction condition for all three rooms.
Same-Temperature System Layout:
Why This Layout Works Well:
In this type of project, the system usually controls well as long as the load calculations, piping, and component selection are correct.
Mixed-Temperature Rooms: Chiller and Freezer on One Unit
When one condensing unit serves a chiller and a freezer, the design becomes more difficult.
The reason is straightforward: the freezer needs a lower suction pressure. If the chiller shares that same low suction condition directly, the chiller evaporator can run too cold. That can cause overcooling, coil icing, unstable room temperature, or even product freezing inside the chiller.
Example:
Trong tình huống này, a basic shared system usually does not perform well by itself. The chiller room branch often needs an EPR valve.
What an EPR Valve Does
An EPR valve helps the warmer room keep a higher evaporator pressure.
You usually install the EPR valve in the suction line of the warmer room, after the evaporator and before the common suction header.
EPR Valve Logic:
With this arrangement:
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The freezer branch follows the lower suction condition it needs.
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The chiller branch stays at a higher evaporator pressure because the EPR valve holds it there.
That is how one condensing unit can serve two different temperature rooms more safely.
When a CPR Valve May Help
Some projects also need a CPR valve near the compressor suction.
A CPR valve protects the compressor during startup or hot pull-down. If several rooms call for cooling at the same time, or if warm product enters the rooms, suction pressure can rise quickly. That high suction pressure can overload the compressor.
CPR Valve Logic:
How to Configure the System Step by Step
A good one-condensing-unit multi-room design usually follows this process:
Bước chân 1: Confirm Basic Project Data
Bước chân 2: Calculate the Load for Each Room
You should calculate each room separately.
Main Load Items:
This step gives you the required evaporator capacity for each room.
Bước chân 3: Select One Evaporator for Each Room
Don’t make all evaporators the same unless the rooms truly have the same load and same operating conditions.
Bước chân 4: Select the Condensing Unit for Combined Demand
This step is where many projects go wrong.
Some people size the condensing unit only by looking at one room. That approach often creates trouble during startup, heavy use, or simultaneous cooling demand.
Condensing Unit Selection Checklist:
The condensing unit must match the system demand under real operating conditions, not just ideal lab conditions.
Bước chân 5: Design the Refrigerant Piping
A multi-evaporator system needs good piping design because it must work in both full-load and part-load conditions.
Piping Rules:
A system may run with all rooms cooling together today, then only one small room may call for cooling tonight. Your piping must support both conditions.
Bước chân 6: Add Room-by-Room Controls
Independent room control is the heart of a multi-room system.
Standard Control Arrangement:
Each room should control its own refrigerant feed. Without that, one room can keep cooling when it no longer needs cooling.
Bước chân 7: Use Pump-Down Control
Pump-down control helps protect the compressor.
Pump-Down Sequence:
This method helps reduce liquid refrigerant migration during off cycles.
Bước chân 8: Plan Defrost for Each Room
Different rooms often build frost at different rates.
Defrost Factors:
It is usually better to stagger defrost schedules instead of defrosting all evaporators at the same time.
Example 1: Three Similar Chiller Rooms
This example shows a standard same-temperature project.
Project Data:
Because the room temperatures are close, one shared condensing unit usually makes sense.
Recommended Configuration:
Operating Logic:
This type of project gives the best balance of simplicity, trị giá, and stable operation.
Example 2: One Chiller and One Freezer
This example shows a mixed-temperature project.
Project Data:
Recommended Configuration:
Operating Logic:
This design can work well, but it needs better pressure control and more careful setup than a same-temperature system.
Example 3: Energy Consumption Comparison
Câu hỏi: “How much electricity can 1 condensing unit save when it serves 3 phòng lạnh, compared with using 3 separate condensing units?”
Tốt, there is no fixed number.
For a project like the example above: one condensing unit serves 3 cold rooms usually saves about 5% ĐẾN 15% điện (if you use inverter condensing unit can save roughly 25% ĐẾN 35%) compared with 3 separate condensing units when the rooms have similar temperatures, similar operating hours, and good piping design.
Simple answer:
Why one unit can save power:
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One larger condensing unit often runs more efficiently than three small units.
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A shared system can reduce cycling losses.
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One system can use capacity more smoothly when room loads change.
But savings can disappear:
Easy example:
If 3 separate units use 100 kWh/day, one shared unit for the same 3 similar rooms may use about 85 ĐẾN 90 kWh/day.
NOTICE: Actual savings depend on room temperature, load diversity, piping, and control design.
Common Mistakes
Most Common Design Errors:
Phần kết luận
One condensing unit can run multiple cold rooms well when you match room temperatures, size each evaporator correctly, and design the controls and piping with care.
For mixed-temperature projects, add the right pressure controls, such as EPR, to protect room stability and product quality. A well-planned one-to-many system can lower cost, tiết kiệm không gian, and deliver reliable performance.
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