Lennox CHA16 Service Manual page 37

1st Stage Heat Demand
Pilot Relay K9
2nd Stage Heat Demand
Pilot Relay K19
4th Stage
Time Delay DL5
(50 kW 208/230v
units only)
3rd Stage
Time Delay DL4
(40kW and 50 kW
208/230V units only)
2nd Stage
Time Delay DL2
(all units equipped
with multiple stage
heaters)
Primary Limit S15
(208/230V only)
Redundant Limit S63
(460 & 575V only)
Primary Limit S15
(460 & 575V only)
Patch Plate
(in lieu of limit
208/230V only)
Secondary Limit S20
(2 each element)
208/230V,10 kW-2
208/230V,15kW-2
208/230V,30kW-4
208/230V,40kW-6
208/230V,50kW-8
460V & 575V,10kW-2
460V & 575V,15kW-2
460V & 575V,30kW-4
460 & 575V,40kW-6
460V & 575V,50kW-8
Contactor K18
4th Stage
(50 kW 208/230v units)
DL5
K9
K18
K19
DL4
DL2
Contactor K17
Contactor K16
3rd Stage
(40kW and 50 kW
(208/230v 30kW and
208/230V units only)
all 40 kW & 50 kW units)
K17
F3
F3
T2
Electric Heat
Transformer T2
Page 37
2nd Stage Contactor K15
1st Stage (all units)
K15
K16
F3
F3
GND
L3 L2 L1
1st Stage Fuse F3
(all units)
4th Stage Fuse F3
(208/230V, 50kW only)
2nd Stage Fuse F3
(460 & 575V units
if equipped with
multiple stages)
2nd Stage Fuse F3
(208/230V units if
equipped with
multiple stages)
3rd Stage Fuse F3
(208/230V units
if equipped with
multiple stages)
Electric Heat
Terminal Strip TB3