Bard WGEIFM-5C Spécifications télécharger pdf (Page 38)

Manual 2100-590C

Page 38 of 67

30. SEQUENCE OF OPERATION –

HEATING

On a call for heat from the thermostat, the induced

draft blower is energized. Once sufﬁcient draft is

established, the pressure switch contacts close and

the ignition system is energized. The direct spark

ignitor will be energized allowing gas to ﬂow. At the

same time the main valve is energized, a 30-second

blower delay timer is activated.

After this delay, the heating speed blower relay

energizes. The blower will begin operating and

remain in operation until the set delay time after the

call for heat has been satisﬁed. (See Tables 10-15

for selectable blower off time delays.) This timing

sequence guarantees blower on, blower off operation.

This unit is equipped with a ﬂame roll-out switch,

which is wired in series with the control circuit. This

is a manual reset switch and is used for the purpose of

preventing possible ﬁre hazard in the event of a system

malfunction. If this switch has opened the control

circuit, there could be a possible system malfunction.

Some of the conditions that might cause a roll-out

to occur are blockage or sooting of primary heat

exchanger, overﬁring of furnace due to improper main

burner oriﬁces or incorrect manifold pressure,

insufﬁcient combustion air, or installation deﬁciencies

with respect to return air duct design or sizing.

Once the problem has been resolved, reset the switch

by pressing down on the reset button on top of the

switch. See Figure 19 for additional information.

31. SEQUENCE OF OPERATION –

COOLING

On a call for cooling from the room thermostat, the

high speed blower relay will be energized as well as

the compressor contactor. Following termination of the

cooling cycle, the blower motor will continue to run for

one minute.

See Figure 19 for additional information.

The unit may be equipped with a low ambient control

for lower outdoor temperature operation in the cooling

mode. If equipped with this optional control the

condenser fan will not operate immediately upon

compressor start-up, and will cycle on and off until the

condensing pressure remains above 180 PSIG. LAC

energizes the fan motor at 280 PSIG, de-energizes at

180 PSIG.

FIGURE 19

SEQUENCE OF OPERATION

ELECTRONIC BLOWER CONTROL

Action System Response

Thermostat calls for heat

(W terminal is energized).

• Combustion air blower is energized.

• Air proving switch makes. Airﬂow is established.

• Ignition system is energized.

• Gas valve opens and main burner lights.

• Heat fan on delay timing begins. When timing is complete, the circulating fan is

energized at heat speed.

Thermostat ends call for heat. • Ignition system is de-energized and gas valve closes.

• Combustion air blower is de-energized after postpurge timing.

• Heat fan off delay timing begins. When timing is complete, the circulating fan is

de-energized.

Thermostat begins call for cool

(G and Y terminals re-energized).

• Cooling contactor is energized.

• Circulating fan is energized on cool speed after cool fan on delay timing.

Thermostat begins call for fan

(G terminal is de-energized).

• Circulating fan is de-energized

Limit (ﬂame rollout) opens. • Thermostat and ignition system are de-energized and gas valve closes.

• Combustion air blower and circulating fan heat speed are energized.

Limit (auto reset) or ﬂame rollout

(manual reset) circuit closed.

• Combustion air blower remains energized for postpurge timing.

• The circulation fan remains energized for the selected delay off timing.

• Normal operation resumes.

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Bard WGEIFM-5C Spécifications Page 38

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