Bryant 315AAV instruction manual Sequence of Operation, Fire Or Explosion Hazard

13.Reconnect wires to the following components (Use con- nection diagram on wiring label, if wires were not marked for reconnection locations.):

a.Draft safeguard switch.

b.Inducer motor.

c.Pressure switches.

d.Limit overtemperature switch.

e.Gas valve.

f.Hot surface igniter.

g.Flame-sensing electrode.

h.Flame rollout switches.

14.Reinstall internal vent pipe, if applicable.

15.Reinstall vent connector on furnace vent elbow. Securely fasten vent connector to vent elbow with 2 field-supplied, corrosion-resistant, sheet metal screws located 180_ apart.

16.Replace blower access door only if it was removed.

17.Set thermostat above room temperature and check furnace for proper operation.

18.Verify blower airflow and speed changes between heating and cooling.

!WARNING

FIRE OR EXPLOSION HAZARD

Failure to follow this warning could result in personal injury, death, and/or property damage.

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.

19. Check for gas leaks.

Sequence of Operation

NOTE: Furnace control must be grounded for proper operation or else control will lock out. Control is grounded through green/yellow wire routed to gas valve and burner box screw. Using the schematic diagram in Fig. 53, follow the sequence of operation through the different modes. Read and follow the wiring diagram very 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.

1.Two-Stage Heating (Adaptive Mode) with Single-Stage Thermostat

See Fig. 27 - 34 for thermostat connections

NOTE: The low-heat only switch SW1-2 selects either the low-heat only operation mode when ON, (see item 2. below) or the adaptive heating mode when OFF in response to a call for heat. (See Table 10.) When the W2 thermostat terminal is energized it will always cause high-heat operation when the R-to-W circuit is closed, regardless of the setting of the low-heat only switch. This furnace can operate as a two-stage furnace with

asingle-stage thermostat because the 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.

315AAV

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