Lennox O23 User Manual

Page 15
TABLE 7
PRIMARY LIMIT CONTROL (S10)
UNIT
ACTUATES
ON TEMP. RISE
ACTUATES
ON TEMP. FALL
O23Q2−70 210F (99C) 180F (82C)
O23Q3−105/120 220F (104C) 190F (88C)
O23Q5−140/154 210F (99C) 180F (82C)
OHR23Q3−105/120 240F (116C) 210F (99C)
OHR23Q5−140/154 190F (88C) 160F (71C)
OF23Q3−105/120
OF23Q3−105/120R
240F (116C) 210F (99C)
OF23Q5−140/154
OF23Q5−140/154R
210F (99C) 180F (82C)
FIGURE 12
INSULATING COVER
LIMIT CONTROL (S10)
SPADE CONNECTORS
LIMIT
D−Blower Compartment (Figure 13)
Blower motor (B3), capacitor (C4), and secondary limit con
trol (S21) are located in the blower compartment. The blow
er compartment can be accessed by removing the blower
access panel.
FIGURE 13
BLOWER COMPARTMENT
(OHR23 SIDE VIEW SHOWN)
BLOWER
MOTOR
CAPACITOR
(C4)
SECONDARY LIMIT
CONTROL (S21)
(OHR23 ONLY)
(BACK SIDE)
BLOWER MOTOR
(B3)
1.Blower Motor (B3) and Capacitor (C4)
All O23, OHR23, and OF23 series units use single phase
direct drive blower motors. All motors used are 115V perma
nent split capacitor motors to ensure maximum efficiency.
See SPECIFICATIONS tables for horsepower and motor
nameplate for capacitor rating.The blower motor is con
nected to the blower control board via the blower motor
plug P43.
2.Secondary Limit Control (S21)
The secondary limit (S21) is used on the OHR23 series unit
only. The N.C. limit is mounted on the side and toward the
back of the blower housing. See figure 13 for location and fig
ure 14 for type. When excess heat is sensed in the blower
compartment, the limit will open. If the limit is tripped, the blow
er control deenergizes the thermostat, inturn shutting down
the unit. The limit automatically resets when unit tempera
ture returns to normal. The switch opens at 150F + 5F
(65.5C + 2.8C) on a temperature rise and resets at
140F + 5F (60.0C + 2.8C) on a temperature fall. The
switch is factory set and cannot be adjusted. The set
point is printed on the face plate of the limit.
FIGURE 14
SECONDARY LIMIT CONTROL (S21)
E−Optional Accessories
Optional accessories are available from Lennox for the O23,
OHR23, and OF23 series units. Some accessories are in kit
form which come with instructions.
1.Low Speed On − Off Switch (S68)
The low speed on  off switch is a kit (catalog # 67H91) which
permits continuous low speed blower operation. The switch is
a DPDT toggle switch.
2.Economizer Relay (K43)
The economizer relay (catalog # 65G40) is used to energize
the economizer if used. The relay is a 120V coil, single pole
contact which is energized by the accessory terminal of the
blower control board.

Lennox O23 Specifications

General

Brand	Lennox
Model	O23
Category	Furnace
Language	English