Lennox CHA16 User Manual

Page 63
CHA162553, 2753, 3003 Operation Sequence: B41 Section and C1
Sections
(Basic Unit with Basic Electromechanical Thermostat)
Blower Operation:
1- Blower demand from thermostat terminal G energizes pilot relay K46.
2- N.O. K461 closes energizing blower contactor K3 and energizes the econo
mizer (If installed). Outdoor damper drives to minimum position.
3- N.O. K31 closes, blower begins operation.
1st Stage Cooling:
4- Cooling demand energizes Y1 and G in the thermostat. G energizes
blower (see step 1).
5- After a delay from DL8 (30 second on delay, 240 second off delay), Y1 ener
gizes pilot relay K66 after passing through N.C. Freezstat S49, N.C. High
Pressure limit S4 and Loss of Charge Switch S24.
6- N.O. K661 closes and 24VAC energizes Fan Start Relay K127and
Compressor Contactor K1 after passing through N.C. compressor moni
tor switch S3.
7- K11 closes energizing compressor.
8- K1271 closes energizing Condenser Fan contactor K10.
9- N.O. K101 closes energizing condenser fan motor B4.
2nd Stage Cooling:
10- After a delay from DL9 (30 second on delay, 240 second off delay), sec
ond stage cooling demand Y2 is routed through N.C freezstat S50, high
pressure limit S7 and low pressure limit S25 energizing pilot relay K67.
11- N.O. contacts K671 close energizing Compressor Contactor K2 and
Condenser Fan 2 Contactor K68.
12- N.O. contacts K21 close energizing compressor B2.
13- N.O. contacts K681 close energizing condenser fan motor 2 (B5).
1st Stage Heating: (See CHA161853 with Electric Heat Pages 5657)
14- Heating demand energizes W1 in the thermostat. Pilot relay K77 is
energized.
15- N.O. K771 close energizing electric heat stage 1 The operation se
quence of electric heat units varies depending on size (kW input rating)
and line voltage rating.
2nd Stage Heating (If equipped with multiple stage heating):
(See CHA161853 with Electric Heat Pages 5657)
16- Additional heating demand energizes W2 in the thermostat. Pilot relay
K49 is energized.
17- N.O. K491 close energizing electric heat stage. The operation se
quence of electric heat units varies depending on size (kW input rating)
and line voltage rating.
Safety Blower Operation:
18- If either limits in the electric heat section trip, the heating elements are im
mediately deenergized.
19- The indoor blower remains energized powered by K3 which is ener
gized by thermostat demand.

Lennox CHA16 Specifications

General

Brand	Lennox
Model	CHA16
Category	Air Conditioner
Language	English