Page 4
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.
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.
FIGURE 4
SCROLL
HOW A SCROLL WORKS
SUCTION
SUCTION
SUCTION
MOVEMENT OF ORBIT
STATIONARY SCROLL
ORBITING
CRESCENT
SHAPED GAS
POCKET
HIGH
PRESSURE
GAS
DISCHARGE
POCKET
FLANKS
SEALED BY
CENTRIFUGAL
FORCE
12
3
4
SUCTION
INTERMEDIATE
PRESSURE
GAS
SUCTION
POCKET
FIGURE 5
Bypass Ports
Closed
High Capacity
Bypass Ports
Open
Low Capacity
TWO−STAGE MODULATION
To Next Page
Loading...
Need help?
General
