1. The Importance of the Solenoid Valve
The solenoid valve plays a crucial role in stopping the flow of refrigerant to the thermostatic expansion valve when the system needs to shut down.
- Functionality:
When the solenoid valve closes, the refrigerant stops circulating. This allows the low-pressure switch to detect insufficient pressure and turn off the equipment, reducing risks during compressor startup. - Recommended Placement:
Install the solenoid valve as close as possible to the evaporator for efficient operation.
2. Positioning the Thermostatic Expansion Valve
The thermostatic expansion valve should be installed above the level of the evaporator to ensure smooth refrigerant flow into the evaporator.
- Sensor Bulb Placement:
- Position the bulb on a horizontal section immediately after the evaporator outlet.
- Avoid:
- Placing the bulb on vertical sections.
- Installing the bulb after an oil trap or siphon.
3. Recommendations Based on Pipe Diameter
The position of the sensor bulb varies depending on the pipe diameter:
- Pipe diameter 3/8 to 5/8 inches: Place the bulb between the 11 o’clock and 1 o’clock positions on an imaginary clock face.
- Pipe diameter 3/4 to 7/8 inches: Place the bulb between the 10 o’clock and 2 o’clock positions.
- Pipe diameter greater than 7/8 inches: Place the bulb between the 9 o’clock and 3 o’clock positions.
4. Large Evaporators
For large systems:
- The thermostatic expansion valve can be placed inside the evaporator casing.
- The solenoid valve should be near the expansion element.
- It is crucial to position the valve at the top for optimal performance.
5. Thermal Insulation of the Sensor Bulb
Use thermal insulating material to protect the sensor bulb from exposure to hot air currents or elevated temperatures. This ensures precise control of superheat, defined as the temperature increase of the refrigerant after it has completely transitioned to a gaseous state.
