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RT-SVX34V-EN
At Shutdown
When a Scroll compressor shuts down, the gas within the
scroll compressor expands and causes momentary reverse
rotation until the discharge check valve closes. This results
in a “flutter” type sound.
At Low Ambient Startup
When the compressor starts up under low ambient
conditions, the initial flow rate of the compressor is low due
to the low condensing pressure. This causes a low
differential across the thermal expansion valve that limits
its capacity. Under these conditions, it is not unusual to
hear the compressor rattle until the suction pressure climbs
and the flow rate increases.
During Normal Operation
The scroll compressor emits a higher frequency tone
(sound) than a reciprocating compressor.
Compressor Crankcase Heaters
Each compressor is equipped with a crankcase heater.
When the compressor is “Off”, the crankcase heater is
energized. When the compressor is “On”, the crankcase
heater is de-energized. The proper operation of the
crankcase heater is important to maintain an elevated
compressor oil temperature during the “Off” cycle which
reduces the potential for refrigerant to migrate into the
compressor oil.
If present during a compressor start, liquid refrigerant could
damage compressor bearings due to reduced lubrication
and eventually could cause compressor mechanical
failures.
Prior to the initial start or when power to the unit has been
“Off” for an extended period, allow the crankcase heater to
operate a minimum of 8 hours before starting the unit.
Charging by Subcooling
The unit is shipped with a complete refrigerant charge.
However, if it becomes necessary to add refrigerant, it
should be done so by adding charge to obtain an
acceptable subcooling as described below. Refer to the
maintenance section for proper refrigerant charging
practices.
The outdoor ambient temperature must be between 65°
and 105° F and the relative humidity of the air entering the
evaporator must be above 40 percent. When the
temperatures are outside of these ranges, measuring the
operating pressures can be meaningless.
With the unit operating at “Full Circuit Capacity”,
acceptable subcooling ranges between 8° F to 16° F.
Measuring Subcooling
WARNING
R-410A Refrigerant under Higher
Pressure than R-22!
Failure to use proper equipment or components as
described below, could result in equipment failing and
possibly exploding, which could result in death,
serious injury, or equipment damage.
The units described in this manual use R-410A
refrigerant which operates at higher pressures than R-
22. Use ONLY R-410A rated service equipment or
components with these units. For specific handling
concerns with R-410A, please contact your local
Trane representative.
1. Measure the liquid line pressure. Using a Refrigerant
R-410A pressure/temperature chart, convert the
pressure reading into the corresponding saturated
temperature.
2. Measure the actual liquid line temperature. To ensure
an accurate reading, clean the line thoroughly where
the temperature sensor will be attached. After securing
the sensor to the line, insulate the sensor and line to
isolate it from the ambient air.
Note: Glass thermometers do not have sufficient
contact area to give an accurate reading.
3. Determine the system subcooling by subtracting the
actual liquid line temperature (measured in step 2) from
the saturated liquid temperature (converted in step 1).
Gas Heat Units
Open the main disconnect switch to shut the unit off.
Follow the Service Test instructions in the Symbio 700
Controller with Voyager 3 Packaged Rooftop Air
Conditioners literature (ACC-APG002A-EN) to put the unit
into active gas heat step.
When starting the unit for the first time or servicing the
heaters, it is a good practice to start the heater with the
main gas supply turned “Off”. The main gas supply valve is
the quarter-turn valve located on the largest gas pipe
leading to the customer connection.
All heating units have either two stage or modulating heat
capabilities. Only 800 MBH heat models contain two heat
exchangers. In staged units, the heat exchangers operate
simultaneously at either the low or high fire state. In
modulating units, the modulating furnace fires first and
adjusts to the needed capacity. If more heat is required
than the modulating can provide, the second bank is fired
and the modulating bank again adjusts to the heating load
present.
Check both ignition systems (if applicable) when going
through the test procedures.
Startup
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