Installation manual
23
ENVISION SERIES INSTALLATION MANUAL
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
pressure 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 eld. Check the service valve ports and stem for leaks
and all connections made in the eld. If a leak is found, repair it and repeat the above steps. For safety reasons do not
pressurize 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
system through both service ports to prevent false readings on the gauge because of pressure drop through service ports.
Initial System Charge
The Envision Split is shipped with a factory pre-charge. This volume of refrigerant is not sufcient to run the system
and additional refrigerant must be added. If using an Envision NAH series air handler refer to page 9 for the initial system
charge amount. The initial system charge in the table includes the factory pre-charge + the required charge for a 20 ft. line
set + the required charge for the air handler. A 3/8 inch liquid line is calculated at 0.50 ounce of charge per linear foot and a
1/2 inch liquid line is calculated at 1.0 ounce of charge per linear foot using R-410A refrigerant. The suction line will not hold
“liquid” and should be ignored for the charge calculation.
Example: NSZ036/NAH036 with a 40 ft. of 3/8 inch liquid line. Remember that the table on page 9 already
includes enough refrigerant for a 20ft. line set. Calculate for required refrigerant needed for an
additional 20ft. of 3/8 inch liquid line.
Additional refrigerant to be added = (20ft x 0.5 oz/ft)
= 10 oz.
Solution: 10 ounces should be added to the recommended initial system charge of 96 ounces for a total of
106 ounces.
After initial charge, the system should be operated and the system subcooling and superheat veried to the Unit
Operating Parameters table.
If an air handler manufactured by others is used then refrigerant should be added to the Envision Split factory charge
pre-charge. Refrigerant should be added for liquid line length. This should result in a slightly under-charged system
exhibiting low subcooling and high superheat. As charge is added, the subcooling should rise and the superheat should fall.
Charging the System
Charge Method – After purging and evacuating the line set, fully open the service valves counterclockwise. Add R-410A
(liquid) into the liquid line service port until the pressure in the system reaches approximately 200 PSIG. Never add liquid
refrigerant into the suction side of a compressor. Start the unit and measure superheat and subcooling. Keep adding
refrigerant until the unit meets the superheat and subcooling values on pages 26 and 27.
Checking Superheat and Subcooling
Determining Superheat
Measure the temperature of the suction line at the point where the expansion valve bulb is clamped.
1.
Determine the suction pressure in the suction line by attaching refrigeration gauges to the schrader connection on the
2.
suction side of the compressor.
Convert the pressure obtained in Step 2 to the saturation temperature by using the R-410A Pressure/Temperature
3.
Conversion Chart on page 25.
Subtract the temperature obtained in Step 3 from Step 1. The difference is the amount of superheat for the unit. Refer to
4.
tables on pages 26-27 for superheat ranges at specic entering water conditions.
Refrigeration (continued)