Cooling - Lennox HP29 Series Manual

6 − Transfer Relay K8 (all units)
Transfer relay K8 ensures that the indoor blower will oper
ate during all modes of operation. K8 also completes the
circuit to Y1 on the defrost control board CMC1. The com
bined operation of latch relay K6 and transfer relay K8 al
lows the HP29 unit to use a conventional heat/cool thermo
stat instead of a heat pump thermostat. When there is a de
mand for cooling, K8−1 closes completing the Y1 circuit to
defrost control board CMC1 terminal Y1. Normally open
K6−1 closes energizing the reversing valve. K8−2 normaly
closed contacts ensure an unbroken circuit between in
door thermostat "G" and indoor blower contactor through
terminals "G" and "G1" on terminal strip TB14. When there
is a heat demand, normally closed K8−1 opens breaking
the Y1 circuit to the defrost control CMC1. Power is sent to
the "RESET" coil on K6. K6−1 opens de−energizing the re
versing valve. K8−2 closes sending voltage from "G1" to
the indoor blower control.
7 − Outdoor Fan Relay K10 (all units)
K68 (HP29−120)
Outdoor fan relay K10 is a DPDT relay and K68 is a SPDT
relay with a 24V coil. In all units K10 energizes outdoor fan
B4 (fan 1) in response to thermostat demand. In the
HP29−120, K68 energizes outdoor fan B5 (fan 2) in re
sponse to thermostat demand.
8 − Terminal Strip TB14 (all units)
TB14 terminal strip distributes 24V power from the thermo
stat to control box components.
9 − Low Ambient Bypass Relay K58
(all units)
K58 is a normally closed DPDT relay with a 24V coil, used
in both HP29−090 and HP29−120 units. K58 is wired paral
lel with the reversing valve L1. When L1 is energized in the
cooling cycle, K58 is also energized, opening K58−1. On
the HP29−120, K58−1 and K58−2 will open. This shuts off
power to the outdoor fans but does not by−pass S11 and
S41, which allow fans to cycle during cooling demand. Dur
ing heating demand, K58 remains closed by−passing S11
and S41 so fans can operate.
10 − GFI− J11 (Optional −2 units)
HP29 units may be equipped with a 110v ground fault in
terrupter (GFI). The GFI is located on the control box panel
on the HP29. Separate wiring must be run for the 110v re
ceptacle.
B−COOLING COMPONENTS
ALL major components (indoor blower/coil) must
be matched to Lennox recommendations for com
pressor to be covered under warranty. Refer to En
gineering Handbook for approved system match
ups.
1 − Scroll Compressor B1
All HP29 units utilize a
scroll compressor.
scroll compressor design
is simple, efficient and re
quires few moving parts.
A cutaway diagram of the
scroll compressor
shown in figure 6. The
scrolls are located in the
top of the compressor can
and the motor is located in
the bottom of the com
pressor can. The oil level
is immediately below the
motor and oil is pressure
fed to the moving parts of the compressor. The lower portion
of the compressor shell is exposed to low side pressure while
only the very top of the shell is exposed to high side pressure.
The scroll is a simple compression concept centered
around the unique spiral shape of the scroll and its inherent
properties. Figure 7 shows the basic scroll form. Two iden
tical scrolls are mated together forming concentric spiral
shapes (figure 9). One
scroll remains station
ary, while the other is al
lowed to orbit (figure
8−1). Note that the orbit
ing scroll does not rotate
or turn but merely orbits
the stationary scroll.
Page 7
IMPORTANT
The
SCROLL COMPRESSOR
DISCHARGE
is
SUCTION
FIGURE 6
FIGURE 7