Lennox CHA16 - A2 diagram with B2 diagram ECH16-82;95;135;160 20 kW & 30 kW 208;230 V Sequence; Operation Sequence: A2 Section and B2 Sections (20;30 kW 208;230 V electric heat wired to CHA16-1603); 1- 1 st stage heating demand closes W1...; 2- When K15-1 closes, heating elements HE1 are energized...

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A2 diagram
with B2 diagram
ECH16-82/95/135/160 20kW & 30kW 208/230V Sequence
Operation Sequence: A2 Section and B2 Sections
(20/30kW 208/230V electric heat wired to CHA16-1603)
1- 1st stage heating demand closes W1. W1 passes through primary limits S15 to energize
contactor K15, relay K9 and time delay DL2. K151 contacts close and K91 and K92 both
switch.
2- When K151 closes, heating elements HE1 are energized. The elements are arranged in a Del
ta" configuration for 208/230V operation.
3- When K91 switches, indoor blower contactor K3 is energized. When K92 switches, time delay
DL2 is enabled (circuit is closed to W2).
4- When K3 is energized, the indoor blower is powered (and optional economizer opens to mini
mum position when K32 contacts close).
5- Additional heating demand W2 passes through K92 to energize time delay DL2.
6- DL2 closes after 30 seconds. Contactor K16 is energized.
7- When K161 closes, heating elements HE2 are energized.