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and ICI EMKARATEt RL32CF for use with these com-
pressors. Lennox recommends adding 1 oz. of oil per addi-
tional 10 ft. for applications with line sets over 50 ft. See
electrical section in this manual for compressor specifica-
tions.
TWO−STAGE OPERATION
The two−stage scroll compressor operates like any stan-
dard scroll compressor with the exception the two−stage
compressor modulates between first stage (low capacity
approximately 67%) and second stage (high capacity).
Modulation occurs when gas is bypassed through bypass
ports (figure 5 bypass ports open) in the first suction pock-
et. This bypassing of gas allows the compressor to operate
on first stage (low capacity) if thermostat demand allows.
SUCTION
SUCTION
POCKET
1
SUCTION
3
HOW A SCROLL WORKS
MOVEMENT OF ORBIT
ORBITING
SCROLL
STATIONARY SCROLL
CENTRIFUGAL
HIGH
PRESSURE
GAS
FIGURE 4
TWO−STAGE MODULATION
Bypass Ports
Closed
High Capacity
FIGURE 5
Indoor thermostat setting will determine first or second
stage operation. The compressor will operate on first−stage
until demand is satisfied or the indoor temperature reaches
the thermostat set point calling for second−stage.
Second−stage (high capacity) is achieved by blocking the
bypass ports (figure 5 bypass ports closed) with a slider
ring. The slider ring begins in the open position and is con-
trolled by a 24VDC internal solenoid. On a Y2 call the inter-
nal solenoid closes the slider ring, blocking the bypass
ports and bringing the compressor to high capacity. Two−
stage modulation can occur during a single thermostat de-
mand as the motor runs continuously while the compressor
modulates from first−stage to second− stage.
SUCTION
2
FLANKS
SEALED BY
SUCTION
FORCE
4
Page 4
INTERMEDIATE
PRESSURE
GAS
CRESCENT
SHAPED GAS
POCKET
DISCHARGE
POCKET
Bypass Ports
Open
Low Capacity
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