AHRI (-)98VA060M317USA, Installation Instructions Manual

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INTEGRATED FURNACE CONTROL
DIPSWITCHES
OFF/OFF - NORMAL OPERATION – MODULATING OR
TIMED STAGING HEAT
When both Mode dipswitches are set to the “OFF” posi-
tion, the furnace operates as normal to a legacy modulat-
ing heat call (“W1” with PWM signal on “V/W2”) with the
firing rate adjusted by the PWM signal. The furnace oper-
ates in timed staging mode when responding to a low heat
call (24 VAC present on “W1” and no signal present on
“V/W2”). A call for low heat alone will start the heating se-
quence as normal and output the low heat rate (40% heat)
for a period of ten minutes followed by a transition to a
65% heating rate. The 65% heating rate will remain active
for the next ten minutes and will be followed by maximum
heat (100% heat) for the remainder of the heating call.
Once the control has switched to high stage heat through
the staging method, the remainder of the heat call will take
place at 100% heat even if a signal somehow becomes
present on “V/W2”. The switch to 65% fire after ten min-
utes and high fire (100% heat) after a total of twenty min-
utes into the heat call will occur as long as there is no 24
VAC signal present at “V/W2”.
If 24VAC is sensed on “V/W2”, 100% heating operation
will take place at the 100% heat rate until the end of cur-
rent heat call as it is assumed that the customer wants to
operate the furnace as a two-stage furnace with no timed
staging. When the “V/W2” terminal becomes inactive while
the “W1” request remains active, the IFC will switch to the
low heat rate (40%). If the unit is already operating at
100% heat rate due to the timed staging algorithm then
the IFC will continue to run at 100% heat rate for the rest
of the heat cycle regardless of whether 24VAC is applied
to or removed from “V/W2”.
If a PWM signal is sensed at terminal “V/W2”, the timed
staging feature will be cancelled until the end of current
heat call and normal modulating heat will take place as
according to Section, item #3. If the unit is already operat-
ing at 100% heat rate due to the timed staging algorithm,
then the IFC will continue to run at 100% heat rate for the
rest of the heat cycle regardless of the PWM signal ap-
plied to the “V/W2” terminal.
Control must be able to sense a change in PWM signal in
no more than 3 seconds.
ON/OFF - LOW HEAT SINGLE RATE MODE
For the single rate mode, when SW10 is “ON” and SW11
is “OFF”, the furnace will operate in the 40% heat mode
with any legacy call for heat (first stage, second stage or
modulating). A legacy heat call will cause the furnace to
go through a normal heating cycle with heating fire rate
fixed at 40%. The voltage at the terminal labeled “V/W2”
will be ignored.
OFF/ON - HIGH HEAT SINGLE RATE MODE
When SW10 is “OFF” and SW11 is “ON”, the furnace will
operate in the 100% heat mode with any legacy call for
heat (first stage, second stage or modulating). That is, a
24 VAC signal on “W1” will cause the furnace to go
through a normal heating cycle with heating fire rate fixed
at 100%. The voltage at the terminal labeled “V/W2” will
be ignored.
ON/ON - RESPONSE TO TWO-STAGE THERMOSTAT
WITH 3 STAGES OF HEAT OPERATION
When both Mode dipswitches are set to the “ON” position,
a 24VAC signal present on “W1” with no signal on “V/W2”
will always operate low-fire heat (40% heat rate). With
24VAC present on both “W1” & “V/W2” the IFC will oper-
ate at 65% gas heat for ten minutes followed by 100%
heat until 24 VAC is no longer present on “V/W2”. This se-
quence will be triggered also when 24VAC signal on
“V/W2” appears during “W1” operation.
When both Mode dipswitches are set to the “ON” position,
the furnace operates as normal to a modulating heat call
(“W1” with PWM signal on “V/W2”) with the firing rate ad-
justed by the PWM signal.
Continuous Fan Speed; SW12
One dipswitch (SW12) is to be provided for legacy contin-
uous fan adjustment.
Selections are as follows:
*SW12 = OFF = 500 CFM for ½ HP
700 for 3/4HP
SW12 = ON = 800 CFM for ½ HP
1200 for 3/4HP
Gas Heat Rise (Airflow) Adjustment; SW13, SW14,
SW15 & SW16
Four dipswitches are to be provided to adjust the low and
high heating temperature rise by changing the airflow. The
switches are to be labeled
“HEAT ADJ”
(SW13 & SW14),
“+/-” (SW15) and “2F/4F”(SW16). These switches will ad-
just the temperature rise by changing the airflow only
when SW13 and SW14 are NOT set to OFF/OFF. SW13
and SW14 will select the method of temperature rise ad-
justment as follows:
Selection SW13 SW14 Description
A OFF OFF No Adjustment*
B ON OFF Adjust High Heat Only
C OFF ON Adjust Low Heat Only
D ON ON Adjust BOTH Low
and High Heat
Together by the
same amount.
SW15 (“+/-“) is mapped as follows:
SW15 OFF = Positive Temperature Rise Adjustment
SW15 OFF = (Airflow is Reduced)*
SW15 ON = Negative Temperature Rise Adjustment
SW15 OFF = (Airflow is Increased)