Installation Guide

39
Call for 1st-Stage Heat - Thermostat contacts close R to W1.
After a successful Light Off Sequence and expiration of the Igni-
tion Stabilization Period:
• The furnace control board adjusts to the low firing rate.
• After 2 minutes, the furnace control board increases the
firing rate to 50% for the next 8 minutes.
• Thereafter, the furnace control board will increase the firing
rate 10%, at a rate of 1% per second, every 10 minutes for
the remainder of the call for heat (See above figure).
• The circulator fan is adjusted to the appropriate CFM,
corresponding to the current firing rate.
Call for 2nd-Stage Heat - Thermostat contacts close R to W1 and
W2.
After a successful Light Off Sequence and expiration of the Igni-
tion Stabilization Period:
• The furnace control board adjusts to the low firing rate of
35%.
• After 2 minutes, the furnace control board increases the
firing rate to 80%.
• Thereafter, the IFC will increase the firing rate by 10%, at
a rate of 1% per second, every 10 minutes for the remainder
of the call for heat.
• The circulator fan is adjusted to the appropriate CFM,
corresponding to the current firing rate.
Call for 2nd-Stage Heat with 1st-Stage call for heat call in progress,
with conventional 2-Stage Thermostat.
• The furnace control board 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 re-
mains.
• The furnace control board remains at the current firing
rate until the 1st-Stage call for heat is satisfied.
HEATING OPERATION WITH CTK01 THERMOSTAT (COMMUNI-
CATING)
• When the Thermostat Heat Setup DIP switch is set to 2-
Stage heat, the furnace control board operation will be
compatible with a CTK01 communicating thermostat.
• When a call for heat is sent, the furnace will go through
the Light Off Sequence, at which time the Heat Current
Demand Status will still show 0%. After the successful
Light Off Sequence and expiration of the Ignition
Stabilization Period:
• The furnace control board adjusts to the low firing rate.
• After 2 minutes, the furnace control board accepts the specific heat requested demand.
• If the differential is equal to or less than 2 degrees, the furnace control board will follow the conventional 2-Stage
algorithm, equivalent to a W1 request and be reflected in the heat current demand status %.
MIN.
50%
60%
(80%)
70%
IGNITION
10 MINS.
8 MINS.
2 MINS.
Operation with Conventional 2-Stage Thermostat
(DIP switch selects 2-stage heat)
Figure 45
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)
Figure 46
MIN.
50%
78%
(80%)
100%
IGNITION
2 MINS.
CALL FOR
2ND STAGE HEAT
UNIT CALL FOR HEAT ENDS
Figure 47