ENVISION SERIES INSTALLATION MANUAL
Refrigeration (continued)
Leak Testing
The refrigeration line set must be pressurized and checked for leaks before purging and charging the unit. To pressurize the line set, attach refrigerant gauges to the service ports and add an inert gas (nitrogen or dry carbon dioxide) until pres- sure reaches 60 to 90 PSIG. Never use oxygen or acetylene to pressure test. Use an electronic leak detector or a good quality bubble solution to detect leaks on all connections made in the field. Check the service valve ports and stem for leaks and all connections made in the field. If a leak is found, repair it and repeat the above steps. For safety reasons do not pres- surize the system above 150 psi. Purge pressure from line set. The system is now ready for evacuating and charging.
System Evacuation
Ensure that the line set and air coil are evacuated before opening service valves to the split unit. The line set must be evacuated to at least 200 microns to remove the moisture and air that may still be in the line set and coil. Evacuate the sys- tem through both service ports to prevent false readings on the gauge because of pressure drop through service ports.
Initial System Charge Calculation
The Envision unit comes with a factory
Addition to Factory Charge = (lineset length x oz. per ft) + (20 oz. for accumulator)
The lineset charge should be calculated by multiplying the length times 0.5 oz./ft for 3/8” liquid line and 1.0 oz/ft for 1/2” liquid line in
Example: 036 with 40 foot of 3/8” liquid line.
Additional to be added = (40 ft x 0.5 oz./ft) + (20 oz. for accumulator) = 40 oz.
Solution: 40 oz. should be added to the existing 56 oz. of factory charge as an initial charge.
Charging the System
Charge Method – After purging and evacuating the line set, fully open the service valves counterclockwise. Add
Checking Superheat and Subcooling
Determining Superheat
1.Measure the temperature of the suction line at the point where the expansion valve bulb is clamped.
2.Determine the suction pressure in the suction line by attaching refrigeration gauges to the schrader connection on the suction side of the compressor.
3.Convert the pressure obtained in Step 2 to the saturation temperature by using the
4.Subtract the temperature obtained in Step 3 from Step 1. The difference is the amount of superheat for the unit. Refer to tables on pages
Superheat Adjustment
TXV’s are factory set to a specific superheat; however, the superheat should be adjusted for the application. To adjust the TXV to other superheat settings:
1.Remove the seal cap from the bottom of the valve.
2.Turn the adjustment screw clockwise to increase superheat and counterclockwise to decrease superheat. One complete 360° turn changes the superheat approximately
30 minutes after the adjustment is made for the system to stabilize.
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