Lennox Harmony III User Manual

55
5.3.4. Dual Fuel Operation (Above Balance Point)
Energize W1
@ furnace
(see NOTE)
No
De-energize
all heat pump
and furnace
stages
Discharge
air falls to
130°F
?
Yes
Yes
No
Yes
Heating
demand
satisfied
?
Yes
Yes
No
No
Yes
No
Energize 1st &/or 2nd stage
ing jumper setting
Discharge
air below heating
staging jumper
setting
?
20-minute
minimum runtime
completed
?
No
No
No
Yes
pressor stages; start
5-minute delay
Shutdown all
compressor
stages
Yes
NOTE - On energize W1 furnace,
compressor heat is locked out - all
heat calls for the next three hours
use gas heat only
Yes
5-min
completion of last
heating
demand
?
Yes
Ambient
temp. Above
Balance Point
sensor setpoint
?
Yes
No
No
See Below Balance Point
sensor setpoint flow diagram
Monitor
discharge air
temperature
Shutdown all
heating stages
Continuous air
delivered to
calling zones
Yes
No
No
Heat pump
locked out
(see NOTE)
YesNo
Monitor
discharge air
temperature
5 min delay
complete
?
YesNo
System
in 3-hr backup
heat mode
?
Yes
No
Discharge
air DAS above
135°F
?
3-minute
minimum runtime
completed
?
Is
discharge
air at upper
limit
?
Does
discharge air
temp. meet
heating staging
differential
?
Heating
demand
satisfied
?
Yes
5 min
delay
complete
?
Heating
demand
satisfied
?
No
HEATING DEMAND
RECEIVED
BLOWER
SHUTDOWN
5.3.5. Defrost Operation
Defrost
control detects
need for defrost
cycle
?
Yes
No
Yes
Harmony III
control energizes
all compressor
stages
Heat Pump
enters defrost
Defrost
completed
?
No
Yes
Harmony III control
de-energizes all
compressor stages - uses
auxiliary heat to complete
existing heat demand
Defrost
period exceeds
20 minutes
?
No
De-energize
all compressor
stages
Yes
No
Heating
demand
satisfied
?
Dual Fuel
?
Yes
No
Harmony III
sends signal to
W1 at indoor unit
Defrost
Te mpering
?
Yes
No
HP cycles W1 OFF at
90ºF and ON at 80ºF
during defrost cycle.
NORMAL
HEAT PUMP
OPERATION

Lennox Harmony III Specifications

General

Brand	Lennox
Model	Harmony III
Category	Control Systems
Language	English