Page 35
ComfortSense
t
Model L7742U Touch Screen 7−Day Programmable Thermostat
LEGEND
HBSP − High Balance Set Point
LBSP − Low Balance Set Point
ODT − Outdoor Temperature
NOTES
LBSP and HBSP must not be set closer than 2ºF
2nd stage lock in temperature −20ºF to 75ºF (OFF)
Temperature
Operation
Heat Pump Heat Only
HBSP
Heat Pump or Gas/Oil Heat
LBSP
Gas/Oil Heat Only
Indoor heat
demand
?
YES
NO
Gas/oil
heat (non−HP)
demand (W1) or EM
heat demand
?
YES
NO
ODT above
LBSP +3
?
YES
Compress-
or speed 1 (Y1
only) ?
ODT
> stg2 (Y2)
lock in temp
?
NO
YES
HP
stage
demand
?
Stg1
Stg2
Energize Y1, B,
G and start
upstage timer
Energize Y1, Y2,
B, G and start
upstage timer
Indoor heat
demand
?
NO
YES
Upstage
timer expired
?
NO
2nd stage
demand
?
YES
YES
ODT
< LBSP − 3
?
NO
YES
NO
Indoor heat
demand
?
NO
YES
NO
3rd stage
demand
?
YES
YES
ODT
< LBSP − 3
?
NO
YES
NO
De−energize
Y1 or Y1&Y2,
and G
2nd stg
HP (Y2) or
Gas (W1)
?
A
ODT
< HBSP − 3 or
(if HBSP is
OFF)
?
W1
Y2
De−energize
W1 and W2
HEAT PUMP
LOCKOUT
Energize 1st
stage gas/oil heat
(W1) and start
upstage timer
Indoor heat
demand
?
Indoor heat
demand
?
Upstage timer
expired
?
Energize W2
4th
stage demand
or 2nd stage gas/oil
demand (W2)
?
NO
YES
YES
NO
NO
YES
NO
YES
NO
YES
NO
YES
NO
A
Upstage
timer expired
?
De−energize
Y1, Y2, G
START
Figure 16. Dual Fuel Flowchart
