Understanding Grille Temperatures in Mini Split Air Conditioners

When discussing the proper grill temperature of a mini split air conditioner, it's important to note that the temperature varies based on several key factors. In the context of a 1 ton mini split AC unit set to 16°C (which is the equivalent of 60.8°F) in an ambient temperature of 37°C (98.6°F), the grill temperature is influenced by a range of variables, including the type of compressor motor, room conditions, and air flow.

What Factors Affect Grill Temperature?

In a typical mini split air conditioner, the grill temperature is primarily related to the differential temperature (Delta T) between the input air and the output air. A nominal Delta T for a properly functioning system is approximately 20°F (11.11°C). However, this can vary based on several factors:

Heat Exchanger Issues: Problems with the heat exchanger can affect the efficiency and temperature reduction. Blower CFM (Cubic Feet per Minute): The power and efficiency of the blower directly impact the air flow and, consequently, the grill temperature. Ambient Temperature: The temperature of the ambient environment can also play a role.

Real-world applications show that the Delta T can range from 18°F to 22°F (10°C to 12.2°C). This means the grill temperature can vary significantly even within a single system.

Factors Influencing Grill Temperature in Detail

Let's break down the key factors that determine the grill temperature in a mini split air conditioner:

Type of Compressor Motor

The type of compressor motor—whether it is on/off or inverter—plays a significant role in determining the grill temperature. On/off units operate in cycles, while inverter units can adjust the cooling intensity continuously. This adjustment affects the grill temperature, particularly when the unit is initially turned on after being idle for a while.

Room Temperature and Air Volume

The room temperature at the time of turn-on and the air volume per minute passing over the cold coils are crucial. When returning from an extended absence, the grill temperature will be the maximum possible degrees cooler than the room temperature, depending on the fan setting. A higher fan setting increases air volume but reduces temperature drop.

As the room approaches the thermostat setting, the inverter unit will adjust its cooling intensity. This reduces the temperature difference between the room and the grill temperature.

Evaporator Temperature

The evaporator temperature is the part of the mini split unit that does the cooling, and it can vary based on the specific model. Typically, the evaporator temperature ranges from 41 to 52°F (5 to 11°C). This temperature can vary depending on ambient conditions and the refrigerant type, such as R410A.

Practical Considerations

For a mini split air conditioner set to 16°C (60.8°F) in an ambient temperature of 37°C (98.6°F), the grill temperature can be expected to be anywhere between 10°C to 14°C lower than the incoming air temperature, which is approximately 27°C to 31°C. As the room temperature drops closer to the set temperature, the grill temperature will also approach the set point.

If the indoor temperature is around 30°C (86°F), the grill temperature should be around 19°C to 21°C (66°F to 70°F). When the indoor temperature drops to 25°C (77°F), the grill temperature should be around 15°C (59°F).

Additionally, it's important to check the outdoor coil to ensure it is not clogged with dirt. Regular maintenance, such as washing the outdoor coil with a garden hose, can help maintain optimal performance.

Conclusion

Understanding the grill temperature in a mini split air conditioner involves considering several factors, including the type of compressor, room conditions, and air flow. Regular maintenance and keeping the outdoor coil clean are essential for efficient and effective cooling.