How to Size A Compressor

Getting the right size refrigerator compressor is crucial for efficiency, performance, and durability. Oversized compressors cycle off too quickly, leading to an increasing in the pressure and temperature. Undersized units struggle to maintain desired temperatures, running constantly, which shortens their lifespan and risks food safety.

We suggest looking at the model number of your current compressor unit to find similar specifications. If you don't have access to the worn compressor, find the refrigerator model number instead. Knowing the parts you're working with can simplify the process of replacement.

Larger compressors have faster rates of refrigerant circulation than smaller compressors. Small compressors also tend to operate more quietly than larger compressors. In most cases, the relative size of the compressor depends on the type of cooling system being repaired.

With the old model number, you can call the manufacturer or one of our support representatives for a compatible replacement, hassle-free.

If that method doesn't help (or the sticker faded), take the following into consideration:

• Refrigerator size: Industrial refrigeration for larger spaces requires robust refrigeration systems. Big and tall freezers need more power to operate. Therefore, they usually need larger compressors with more power to boast. Likewise, smaller refrigerators in residential areas don't need to be as powerful. These may only need low voltage mini compressors to get the job done.
• Refrigerator/Fridge Use: Frequent door openings increase compressor workload by allowing warm air in. Refrigerators with heavy use may require high-capacity models to keep output consistent even when the door is open.
• Desired Noise Levels: For max comfort, consider compressor noise levels, measured in decibels (dB). The higher decibels, the louder the refrigerator compressor unit.
• Load requirements: You need a compressor that doesn't exceed the voltage requirements of your refrigerator. Too high and your system will overload, too low and the system will underperform.
• Maintenance and Longevity: Consider maintenance needs and longevity when choosing a compressor. Don't skip on a unit with a longer lifespan. Units with longer lifespans don't need replacing as quickly, saving you money in the long run.
• Connection Sizes: The connection of your refrigerator, or fridge, must match those of the soon to be installed compressor. If not, the lines will leak and cause damage to the system.

When choosing a compressor for your refrigerator, make sure to consider the compressor capacity along with temperature and pressure levels. Compressor capacity is reflected as CFM, or cubic feet per minute, and is proportional to the cooling potential of the unit. The higher the CFM rating, the higher the compressor's cooling capacity.

For example, a compressor with 2500 CFM can get much colder than a unit with 500 CFM. Your choice would change depending on room pressure levels and temperature. Rooms with higher temperatures require a higher CFM to properly cool.

Different types of compressors operate differently based on refrigeration cycles and how they compress the refrigerant gas. We offer a full range of Embraco compressors, including:

• Open compressors (semi-hermetic)
• Hermetic compressors
• Piston compressors
• Screw compressors
• Spiral compressors

If you are on a budget and need an economical option, you could choose an inexpensive hermetic compressor. Hermetic compressors are not repairable because of their construction. This can be costly to fix in the future. Semi-hermetic compressors are more easily repaired but have a higher cost of entry.

If you require higher-pressure operating compressors, you could choose a cost-effective piston compressor or a screw compressor. This decision would be based on your specific power and performance requirements.

It is important to find a compressor with the similar product specifications as the model being replaced. If possible, match the horsepower, voltage, electrical phases, torque properties, and temperature capacity of the previous model. Understanding fridge compressor size involves two key measurements: BTUs and HP. BTUs (British Thermal Units) measure cooling capacity—the higher the BTU, the more cooling power. HP (horsepower) indicates compressor work capacity—a higher HP means a stronger compressor. Both are crucial for gauging compressor size and capacity.

• Electrical phase: The phase represents the electrical current moving between existing and neutral wiring. Single-phase is common in residential settings, while Three-phase is used more in industrial applications.
• Voltage: This is the electrical potential difference required for the compressor to operate.
• Torque: Measures the rotational force produced by the compressor’s motor, affecting its ability to start and maintain operation under load.
• Temperature capacity: Indicates the range of temperatures the compressor can effectively operate in, with low being the coldest and high being the highest temperature setting

When sizing compressors, the compression ratio is discharge pressure over the suction pressure at each stage of the compression process. This ratio is crucial for selecting the right compressor because it shows the compressor's ability to pressurize the refrigerant effectively.

The most common compressor ratios are between 2.3:1 to 3.5:1.

In the context of refrigeration systems, the compression ratio is used to describe the performance of the compressor. The compression ratio in refrigeration is defined as the ratio of the absolute discharge pressure to the absolute suction pressure. The formula is:

Where:

• P_d is the absolute discharge pressure (the pressure at the outlet of the compressor).
• P_s is the absolute suction pressure (the pressure at the inlet of the compressor).

These pressures are typically measured in absolute terms (e.g., psia or kPa absolute), not gauge pressure. This ratio is important because it affects the efficiency and the operational limits of the refrigeration system.

To ensure efficient cooling, the compressor's ratio must match the refrigerator's cooling needs. A ratio that is too low means the refrigerant won't be compressed enough, leading to poor cooling. On the other hand, a ratio that is too high can cause excessive energy use and wear on the compressor.

Another way to determine the appropriate compressor size is by measuring the refrigerator's dimensions and calculating the volume of air that needs to be cooled.