34
MIN.
50%
60%
(80%)
70%
IGNITION
10 MINS.
8 MINS.
2 MINS.
90%
Operation with Conventional 2-Stage Thermostat
(DIP switch selects 2-stage heat)
Call for 2nd-Stage Heat - Thermostat contacts close R to
W1 and W2.
After a successful Light Off Sequence and expiration of the
Ignition Stabilization Period:
•
The IFC adjusts to the low firing rate.
•
After 2 minutes, the IFC increases to 80%.
•
Thereafter, the IFC will increase 10%, at a rate of 1%
per second, every 10 minutes for the remainder of
the call for heat.
•
The circulator is adjusted to the appropriate CFM,
corresponding to the current firing rate.
O
P
E
R
A
T
I
O
N
MIN.
50%
78%
(80%)
100%
IGNITION
2 MINS.
CALL FOR
2ND STAGE HEAT
UNIT CALL FOR HEAT ENDS
Call for 2nd-Stage Heat with 1st-Stage call for heat call in
progress, with conventional 2-Stage Thermostat.
•
The IFC increases the firing rate to 100% at a rate of
1% per second for the remainder of the W2 call.
•
The circulator is adjusted to the appropriate CFM,
corresponding to the current firing rate.
Call for 2nd-Stage Heat satisfied; Call for 1st-Stage Heat
remains.
•
The IFC remains at the current firing rate until the
1st-Stage call for heat is satisfied.
H
EATING
O
PERATION
WITH
CTK01 T
HERMOSTAT
(C
OMMUNI
-
CATING
)
•
When the Thermostat Heat Setup DIP switch is set to
2-Stage heat, the IFC operation will be compatible
with a CTK01communicating thermostat.
•
When a call for heat is sent, the furnace will go through
the Light Off Sequence, After the successful Light
Off Sequence and expiration of the Ignition Stabili-
zation Period:
•
The IFC adjusts to the low firing rate.
•
After 2 minutes, the IFC accepts the specific Heat
Requested Demand.
•
If the differential is equal to or less than 2 degrees,
the IFC will follow the conventional 2-Stage algorithm,
equivalent to a W1 request..
•
If the heat differential is greater than 2 degrees, the
IFC will follow the conventional 2-Stage algorithm,
equivalent to a W2 request.
•
The circulator will operate per the heat airflow pro-
file.
H
EATING
O
PERATION
WITH
CTK02**, CTK03 & CTK04
T
HERMOSTAT
(M
ODULATING
C
OMMUNICATING
)
•
When the Thermostat Heat Setup DIP switch is set to
1-Stage heat, the IFC operation will be compatible
with a modulating communicating thermostat
(CTK02**).
•
When a call for heat is sent, the furnace will go through
the Light Off Sequence, After the successful Light
Off Sequence and expiration of the Ignition Stabili-
zation Period:
•
The IFC adjusts to the low firing rate.
•
After 2 minutes, the IFC accepts the specific Heat
Requested Demand.
•
If the differential is 2 degrees or less, the Heat Cur-
rent Demand Status will show 50%.
•
If the specific Heat Requested Demand is above 2
degrees, the Heat Current Demand Status will track
the specific Heat Requested Demand.
•
The circulator will operate per the heat airflow pro-
file.
D
RAIN
T
RAP
P
RIMING
The drain trap must be primed prior to furnace startup. To
prime, fill the drain trap with water. This ensures proper fur-
nace drainage upon startup and prohibits the possibility of flue
gases escaping through the drain system.
OPERATION
