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*
Ramping
Profile
Tap A
Ramping
Profile
Tap B
Ramping
Profile
Tap C
Ramping
Profile
Tap D
Ramping Profiles
*
(
indicates factory setting)
6. Select the heating speed from the heating speed chart in the
Product Data Book applicable to your model* for your model.
The adjust setting (already established by the cooling speed
selection) determines which set of speeds are available. The
selected speed must provide a temperature rise within the
rise range listed with the particular model.
Example:
The *MV90704BXA is set for 990 CFM on
cooling, the "ADJUST" is set to "-" (minus). The
four heating speeds available are "A Minus",
"B Minus", "C Minus", and "D Minus". "A Minus"
has a rise of 56°F for both stages which is within
the 30-60°F rise range for the *MV90704BXA.
This setting will keep electrical consumption to
a minimum. Set the "Heat" speed DIP switches
to "A".
7. Select the desired "heating" speed tap by positioning switches
7 and 8 appropriately. Refer to figure above. Turn off power
to furnace for a minimum of 10 seconds, allowing motor to
reset and recognize new speed selection. Turn on power to
furnace. Verify selected CFM by counting the green CFM
LED blinks.
In general lower heating speeds will: reduce electrical consump-
tion, lower operating sound levels of the blower, and increase the
outlet air temperature delivered to the home. The speeds available
allow the blower performance to be optimized for the particular
homeowner's needs.
B
H
O
D
LOWER
EAT
FF
ELAY
The integrated control module provides a selectable heat off delay
function. The heat off delay period may be set to 90, 120, 150, 180
seconds using the DIP switches or jumper provided on the control
module. The delay is factory shipped at 150 seconds but may be
changed to suit the installation requirements and/or homeowner pref-
erence. Refer to the following figures for switch positions and corre-
sponding delay times.
*NOTE: Please contact your distributor or our website for the applicable product data book referred to in this manual.
8 7
6 5
4 3 2 1
O
O
F
F
F
F
8 7
6 5
4 3 2 1
O
O
F
N
F
8 7
6 5
4 3 2 1
O
O
N
F
F
8 7
6 5
4 3 2 1
O
O
N
N
T
IMINGS
ON
ON
ON
OFF
OFF
ON
OFF
OFF
(* indicates factory setting)
Heat Off Delay Switches
XV. NO
XV
XV
XV
XV
. NORM
. NO
. NO
. NO
RM
RM
RMAL SEQUEN
RM
AL SEQUEN
AL SEQUEN
AL SEQUENCE O
AL SEQUEN
P
U
OWER
P
The normal power up sequence is as follows:
•
115 VAC power applied to furnace.
•
Integrated control module performs internal checks.
•
Integrated control module flashes LED one time.
•
Integrated control module monitors safety circuits
continuously.
•
Furnace awaits call from thermostat.
H
M
EATING
ODE
The normal operational sequence in heating mode is as follows:
•
R and W1 (or R and W1/W2) thermostat contacts close,
initiating a call for heat.
•
Integrated control module performs safety circuit checks.
•
Induced draft blower is energized on high speed for a 15-
second prepurge. Humidifier terminals are energized with
induced draft blower.
•
Induced draft blower steps to low speed following prepurge.
Low stage pressure switch contacts are closed.
•
Igniter warm up begins upon step to low speed and presence
of closed low stage pressure switch contacts.
•
Gas valve opens at end of igniter warm up period, delivering
gas to burners and establishing flame.
•
Integrated control module monitors flame presence. Gas
valve will remain open only if flame is detected.
•
If the thermostat call is for low heat, gas valve and induced
draft blower will continue on low stage. If the call is for high
heat, the gas valve and induced draft blower will change to
high stage.
•
Circulator blower is energized on heat speed following a fixed
thirty second blower on delay. The circulator blower requires
thirty (30) seconds to ramp up to full speed. Electronic air
cleaner terminals are energized with circulator blower.
•
Furnace is now operating on the specified stage called for
31
Heat Off
3
Delay
2
90 Seconds
1
3
Heat Off
Delay
2
120 Seconds
1
*
3
Heat Off
Delay
2
150 Seconds
1
3
Heat Off
Delay
2
180 Seconds
1
Heat Off Delay
CE O
CE O
CE O
CE OF OPERA
F OPERATI
F OPERA
F OPERA
F OPERA
TIO O O O O N N N N N
TI
TI
TI
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Table of Contents
Troubleshooting
