Startup; Final Refrigerant Charge; Startup Procedure - Trane SCWM Series Installation, Operation And Maintenance Manual

Startup

WARNING
Live Electrical Components!
Failure to follow all electrical safety precautions when
exposed to live electrical components could result in
death or serious injury.
When it is necessary to work with live electrical
components, have a qualified licensed electrician or
other individual who has been properly trained in
handling live electrical components perform these
tasks.
NOTICE
Compressor Damage!
Failure to follow instructions below will cause the
compressor to operate in a vacuum and result in
compressor damage.
Never manually or automatically pump down system
below 7 psig.
NOTICE
Compressor Damage!
Failure to follow instructions could result in compressor
damage.
Keep crankcase heaters on whenever refrigerant is in
the system.
If crankcase heaters have not been on with refrigerant
in the system, turn the crankcase heaters on for a
minimum of 24 hours before starting compressors.
To start the unit, complete the following steps in order.
Review "Preliminary Refrigerant Charging," p.
applicable. Confirm all steps were completed.

Final Refrigerant Charge

If full charge was not used during installation, follow these
steps:
1. Determine remaining charge required by subtracting
charge added during "Preliminary Refrigerant
Charging," p. 29 from the total.
2. With all circuit compressors running, SLOWLY meter
remaining R-410A into the suction line from the LIQUID
charging connection.
PKG-SVX027A-EN
Compressor Damage!
Overcharging system could result in compressor failure
and/or reduced compressor life.
Do not overcharge system. Excessive refrigerant
charging can cause compressor liquid slugging at
startup, and conditions where compressors and/or
condenser fans short cycle.
Compressor Damage!
Failure to follow instructions below could result in
compressor failure and/or reduced compressor life.
To prevent compressor liquid slugging, only add liquid
in the suction line when the compressor is running. Use
extreme caution to meter liquid refrigerant into the
suction line slowly. If liquid is added too rapidly,
compressor oil dilution and oil pumpout could occur.
3. Use an accurate scale to measure and record amount
of R-410A added.
4. After unit has been operating for approximately 30
minutes at full load, measure and record operating
pressures.
5. Repeat for other circuits.
6. Confirm, and adjust charge if needed, by checking
subcooling at AHRI 340/360 full load operating
conditions (80/67°F entering evap, ~300CFM/ton, 85/
95°F EWT/LWT for water-cooled and 95°F OA for air-
cooled).
Note: Water-cooled subcooling should be 8-10°F.
29, if

Startup Procedure

Using the startup log on the following pages, establish
nominal conditions for consistent measurements as
follows:
• Leaving air greater than 60°F
• Entering air temperature = 70 to 90°F
• Entering water temperature > 60°F With all
compressors running at full load:
1. Compute superheat from the suction line pressure and
temperature at the compressor on each circuit. Adjust
the thermal expansion valve settings if necessary.
Superheat should be between 14 and 20°F.
2. Inspect refrigerant flow in the liquid line sight glass.
Flow should be smooth and even, with no bubbles
once the system has stabilized.
NOTICE
NOTICE
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