38
3.5.2. Gas Heating Operation
3-Minutes
since completion
of last heating
demand
?
Energize W1 @
furnace; Ramp
indoor blower to
minimum CFM
setting
Discharge
air above
100°F
?
Discharge
air below heating
staging jumper
setting
?
Ramp indoor
blower to
heating staging
jumper setting
3-Minutes
minimum run time
in 1st stage
completed
?
3-Minutes
minimum run time
in 2nd stage
completed
?
No
Yes
No
Yes
No
No
Yes
Yes
Yes
Yes
No
No
No
Yes
Yes
No
De-energize
W2
Energize W2
@ furnace
Monitor
discharge air
temperature
Yes
No
Yes
No
Yes
No
De-energize
W1 @ furnace
Hold dampers
open for 3½
minutes
Monitor
discharge air
temperature
REFER TO
DISCHARGE AIR
UPPER LIMIT
DIAGRAM
(Page 38) FOR UPPER LIMIT
AND DIFFERENTIAL DETAILS.
Shut down all
heat stages
Is
discharge
air at upper
limit
?
Does
discharge air
temp. meet
heating staging
differential
?
Is
discharge
air at upper
limit
?
Heating
demand
satisfied
?
Heating
demand
satisfied
?
Heating
demand
satisfied
?
Discharge
air falls to
130°F
?
No
Yes
Continuous air
delivered to
calling zones
Yes
5 min
delay
complete
?
No
HEATING DEMAND
RECEIVED
BLOWER
SHUTDOWN
3.5.3. Discharge Air Upper Limit and Differential Temperatures
Discharge air upper limit is
160ºF unless 140ºF DAS
jumper installed
To / from the
appropriate
gas heating or
dual fuel
diagram
Furnace
energized
No
Yes
No
Yes
No
Monitor
discharge air
temperature
Is
discharge
air at upper
limit
?
3-minute
pleted
?
Yes
Differential is 20ºF above
heating staging jumper
setting with the following
exception:
Differential is 15ºF if the
140ºF DAS jumper is in
place on PIAB 1 terminals
and
er is on 120 or 130.
Does
discharge air
temp. meet
heating staging
differential
?
Summary of Contents for Harmony III
Page 80: ...80...
