Sequence Of Operation; Single-Stage Thermostat And Two-Stage Heating (Adaptive Mode) - Carrier 58MVP Installation, Start-Up, And Operating Instructions Manual

SETUP
SWITCH NO.
SW1-1
SW1-2
SW1-3
SW1-4 Comfort/Efficiency Adjustment
SW1-5
SW1-6
SW1-7
SW1-8
Table 10—Blower Off Delay Setup Switch
DESIRED HEATING
SETUP SWITCH (SW1-7 AND SW1-8) POSITION
MODE BLOWER
OFF DELAY (SEC)
90
120
150
180
Never purge a gas line into a combustion chamber. Never test
for gas leaks with an open flame. Use a commercially
available soap solution made specifically for the detection of
leaks to check all connections. Failure to follow this warning
could result in fire, explosion, personal injury, or death.
Step 5—Sequence of Operation
→
Furnace control must be grounded for proper operation, or
control will lock out. Control is grounded through
green/yellow wire routed to gas valve and burner box screw.
Failure to follow this caution will result in intermittent unit
operation.
Using schematic diagram, follow sequence of operation through
different modes. (See Fig. 31.) Read and follow wiring diagram
carefully.
NOTE: If a power interruption occurs during a call for heat
(W/W1 or W/W1-and-W2), the control will start a 90-second
blower-only ON period two seconds after power is restored, if the
thermostat is still calling for gas heating. The amber LED light will
flash code 12 during the 90-second period, after which the LED
will be ON continuous, as long as no faults are detected. After the
90-second period, the furnace will respond to the thermostat
normally.
The blower door must be installed for power to be conducted
through the blower door interlock switch ILK to the furnace
control CPU, transformer TRAN, inducer motor IDM, blower
motor BLWM, hot-surface igniter HSI, and gas valve GV.
Table 9—Furnace Setup Switch Description
SWITCH
NAME
Status Code Recovery
Adaptive Heat Mode
Low Heat
Rise Adjust
CFM per ton adjust
Component Self-Test
Blower OFF delay
Blower OFF delay
Position
SW1-7 SW1-8
OFF
ON
OFF
ON
NORMAL
POSITION
Turn ON to retrieve up to 7 stored status codes for troubleshooting
OFF
assistance when R thermostat lead is disconnected.
Allows 2-stage operation with a single stage thermostat.
Turn ON when using 2 stage thermostat to allow Low Heat opera-
OFF
tion when R to W/W1 closes and High Heat operation when R to
Turn ON to increase Low Heat airflow by 18 percent. This compen-
OFF sates for increased return air temperature caused with bypass hu-
Turn ON to decrease Low Heat airflow by 7 percent and High Heat
ON airflow 8 percent for maximum comfort. On 040 unit will decrease
Low-Heat Airflow 11 percent and High-Heat Airflow 10 percent.
OFF Turn ON for 400 CFM per ton. Turn OFF for 350 CFM per ton.
Turn ON to initiate Component Self-Test for troubleshooting assis-
OFF tance when R thermostat lead is disconnected.
Control blower Off Delay time. Used in conjunction with SW1-8. See
ON or OFF
Control blower Off Delay time. Used in conjunction with SW1-7. See
ON or OFF
SINGLE-STAGE THERMOSTAT AND TWO-STAGE
HEATING (ADAPTIVE MODE)
See Fig. 28 or 61 for thermostat connections
NOTE: Low-heat-only switch, SW1-2, selects either the low-
heat-only operation mode when ON, (see item 2. below) or
OFF
adaptive heating mode when OFF, in response to a call for heat.
OFF
(See Fig. 32.) When the W2 thermostat terminal is energized, it
ON
will always cause high-heat operation when the R to W circuit is
ON
closed, regardless of the setting of the low-heat only switch.
This furnace can operate as a two-stage furnace with a single-stage
thermostat because furnace control CPU includes a programmed
adaptive sequence of controlled operation, which selects low-heat
or high-heat operation. This selection is based upon the stored
history of the length of previous gas heating periods of the
single-stage thermostat.
The furnace will start up in either low- or high-heat. If the furnace
starts up in low-heat, the furnace control CPU determines the
low-heat on time (from 0 to 16 minutes) which is permitted before
switching to high-heat.
If power is interrupted, the stored history is erased. When this
happens, the control CPU will initially select low-heat for up to 16
minutes and then switch to high-heat, as long as the thermostat
continues to call for heat. Subsequent selection is based on stored
history of thermostat cycle times.
The wall thermostat "calls for heat", closing the R to W circuit.
The furnace control CPU performs a self-check, verifies the
low-heat and high-heat pressure switch contacts LPS and HPS are
open.
1. Inducer Prepurge Period-The furnace control CPU turns on
inducer motor IDM and slowly increases the inducer motor
speed. When the low-heat pressure switch LPS closes, inducer
motor RPM is noted by the furnace control CPU, and a 25-sec.
prepurge period begins. The RPM is used to evaluate vent
system resistance. This evaluation is then used to determine
the required RPM necessary to operate the inducer motor
during the low-heat prepurge period and low-heat mode.
NOTE: The heat cycle can start in either high-or low-heat. If a
high-heat cycle is initiated, the furnace control CPU will de-
energize the high-heat pressure switch relay HPSR to close the NC
contact and continues to increase the inducer motor speed after the
low-heat pressure switch LPS closes. When the high-heat pressure
switch closes, inducer motor RPM is noted by the furnace control
37
DESCRIPTION
OF USE
W/W1 and W2 close.
midifier.
Turn OFF when Self-Test is completed.
Table 10.
Table 10.