Bryant 340MAV Sequence of Operation, III. Condensate Drain Protection, Heating Mode

See Fig. 40 for example of possible field drain attachment using 1/2-in. CPVC or PVC tee for vent and A/C or humidifier drain connection.

OPEN STAND

PIPE FOR

A/C OR

HUMIDIFIER

DRAIN

TEE

CONDENSATE TRAP

WIRE TIE(S)

HEAT TAPE (3 WRAPS MINIMUM)

Fig. 41ÐCondensate Trap Heat Tape

SEQUENCE OF OPERATION

A93036

TO OPEN

DRAIN

A94054

Fig. 40ÐExample of Field Drain Attachment

Outdoor draining of the furnace is permissible if allowed by local codes. Caution should be taken when freezing ambient may freeze drain pipe and prohibit draining.

WARNING: Caution should be taken to prevent drain- ing where slippery conditions may cause personal inju- ries. Excessive condensate draining may cause saturated soil conditions which may result in damage to plants.

III.CONDENSATE DRAIN PROTECTION

Freezing condensate left in condensate trap and drain line may cause cracks, and possible water damage may occur. If freeze protection is required, use condensate freeze protection accessory or equivalent 3 to 6 watt per ft at 120v and 40°F self-regulating, shielded, and waterproof heat tape. See Installation Instructions supplied with accessory or heat tape manufacturer's recommenda- tions.

1.Fold heat tape in half and wrap on itself 3 times.

2.Locate heat tape between sides of condensate trap back. (See Fig. 41.)

3.Use wire ties to secure heat tape in place. Wire ties can be positioned in notches of condensate trap sides. (See Fig. 41.)

4.Wrap field drain pipe with remaining heat tape, approxi- mately 1 wrap per ft.

5.When using field-supplied heat tape, follow heat tape manufacturer's instructions for all other installation guide- lines.

CAUTION: Furnace control must be grounded for proper operation, or control will lock out. Control is grounded through green wire routed to gas valve and burner box screw.

Using schematic diagram, follow sequence of operation through different modes. (See Fig. 24.) Read and follow wiring diagram carefully.

NOTE: If 115-v power supply to furnace or blower access panel switch is interrupted during a call for heat, blower operates for 90 sec when power is restored before heating cycle is resumed.

I.HEATING MODE

When wall thermostat calls for heat, R-W circuit closes. Furnace control performs a self-check, verifies pressure switch contacts are open, and starts inducer motor.

1.Prepurge periodÐAs inducer motor comes up to speed, pressure switch contacts close to begin a 15-sec prepurge period.

2.Ignitor warm upÐAt end of prepurge period, ignitor is energized for a 17-sec ignitor warm-up period.

3.Ignition sequenceÐWhen ignitor warm-up period is com- pleted, gas valve opens, permitting gas flow to burners where it is ignited. After 5 sec, ignitor is de-energized and a 2-sec flame-sensing period begins.

HUM terminal on control center is energized with gas valve. See Accessories Ð Humidifier section.

4.Flame sensingÐWhen burner flame is sensed, control begins blower on delay period and continues holding gas valve open.

If burner flame is not sensed, control center de-energizes gas valve and ignition sequence is repeated.

NOTE: Ignition sequence repeats 3 additional times before a lockout occurs. Lockout automatically resets after 3 hr or can be manually reset by turning off 115v (not at thermostat) for 3 sec minimum, then turning it on again.

→5. Blower on delayÐSixty sec after burner flame is proven (40 sec if jumper has been cut for 140 size unit in downflow orientation), blower motor is energized on heating speed. Simultaneously, electronic air cleaner terminal EAC-1 is energized.

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