Lennox SignatureS
tat 81M26 User Manual

505232 06/07
Page 26
Figure 7 shows a Dual Fuel Flowchart for 81M28 Thermostat.
Figure 7
Dual Fuel Flowchart
for 81M28 Thermostat
Abbreviations:
aux = auxiliary
comp = compressor
LBP = Low Balance Point
temp = temperature
tstat = thermostat
Gas heat lock-
out (when set for
aux heat = add
(comp = off))
De−energize
Y1 & G
Energize
W2
Heat pump lockout
(when set for aux heat =
add (comp = off))
NO
YES
Outdoor
temp above
LBP
?
De−energize
W2
Energize
Y1, B & G
YES
NO
YES
NO
De−energize
W2
2nd stage
heat demand
?
Indoor
tstat heat
demand
?
2nd stage
heat demand
?
Indoor
tstat heat
demand
?
2nd stage
heat demand
?
Indoor
tstat heat
demand
?
De−energize
Y1
Outdoor
temp above
LBP
?
YES
NO
NO
YES YES
NO
NO
YES
YES
NO
Wiring DiagramsThermostat wiring connections with various units,
including dual fuel, zone control, and applications that include the Humidi-
trol
®
accessory. See figures 8 and 9.
Figure 8
Typical Condensing Unit/Humiditrol
®
Accessory
Wiring Diagram
RED
YEL
BLU
BLK
BRN
SignatureStat
t
THERMOSTAT
INDOOR
UNIT
OUTDOOR
UNIT
TWISTED PAIR
PUR
OUTDOOR SENSOR (46M98)
BLK
Y1Y2 JUMPER − IN FOR
SINGLE− STAGE COOLING;
REMOVED FOR 2−STAGE
COOLING
RED
BLK
PUR
EDA UNIT
FAN
RELAY
NOTES −
/1\ NOT REQUIRED FOR APPLICATIONS WITHOUT LSOM
/2\ NOT REQUIRED WITH SINGLE-SPEED OUTDOOR FAN)
/3\ NOT REQUIRED FOR SINGLE STAGE
/4\ ON 81M28 MODEL, E/W1 AND W2 TERMINALS MUST BE JUMPERED
TOGETHER FOR MOST APPLICATIONS

Lennox SignatureS
tat 81M26 Specifications

General

Brand	Lennox
Model	SignatureS tat 81M26
Category	Thermostat
Language	English