Hastings DIRECT GAS FIRED ELECTRIC STEAM, Инструкция по установке и обслуживанию

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I. SEQUENCE OF OPERATION
1. Typical sequence of operation – direct gas fired units:
Closing fused disconnect switch supplies 115 volt power to control circuit through 115 volt control transformer. Unit is
ready for operation.
Summer Operation
If three position season switch is in the “summer” position and two position blower switch is “on“, power is supplied
to the two position fresh air/discharge air damper motor. After approximately one minute, the damper motor has
reached its full open position, closing the damper proving switch. Power is supplied to blower motor starter.
Blower motor will run if blower motor overloads are not tripped. Burner is inoperative. System white light in remote
control panel will be operational.
Winter Operation
If three position season switch is in the “winter” position, and if the high limit switch is operational, blower starts as
explained in summer operation above. If air flow is sensed by the air proving switch and auxiliary starter contacts
are closed, power is supplied to burner protectorelay.
If entering air temperature is below the setting of the entering air temperature controller, protectorelay powers igni-
tion transformer and pilot valve opens. When pilot is lit, flame rod detects pilot flame and ignition transformer drops
out of electrical circuit. Main gas solenoid valve opens and pilot lights main burner. The alarm safety switch lock-
out terminals will close if detection of flame (or flame simulating conditions) occurs, if there is a failure to ignite
main flame, or on a loss of flame while burner is running. The alarm lockout terminals will energize the safety lock-
out relay which will open the lockout relay contacts and shut down the blower and burner. Safety lockout light in
remote control panel will be operational.
Burner flame is controlled by the modulating valve and discharge air controller.
Flame is increased and decreased as discharge temperature rises and falls above and below setpoint of discharge
air controller.
2. Typical sequence of operation – electric units:
Closing optional main disconnect switch supplies 115 volt power to control circuit through 115 volt control transformer.
Unit is ready for operation.
Summer Operation
If three position season switch is in the “summer” position and the three position blower switch is in the “on” posi-
tion, power is supplied to the blower motor starter. Blower relay and blower delay timer must be operational.
Blower motor will run if blower motor overloads are not tripped. Heater is inoperative. System white light in remote
control panel will be on if auxiliary blower motor starter contacts are closed. Optional clogged filter light in remote
control panel will be operational if a blocked intake or clogged filter situation occurs.
Winter Operation
If three position season switch is in the “winter” position, heating control relay is operational, and air flow through
unit has been proven by blower air proving switch, the electronic sequencer will modulate for desired heat if power
is supplied to sequencer through sequencer control transformer and automatic reset thermal cutout.
Heating is controlled by the modulating sequencer through the action of the over-riding modulating room thermo-
stat. If the discharge temperature of the unit falls below the setting of the modulating discharge air controller, the
over-riding room thermostat is over-ridden and heating output is increased until the modulating discharge air con-
troller is satisfied.
If the discharge temperature of the unit rises above the setting of the modulating high limit control, the over-riding
room thermostat is over-ridden and heating output is decreased until the modulating high limit control is satisfied.
The sequencer automatically recycles to the off position on any interruption of power.
System heating light in remote control panel will be on when season switch is in the “winter” position.
3. Typical sequence of operation – steam, hot water units:
Closing optional main disconnect switch supplies 115 volt power to control circuit through 115 volt control transformer.
Unit is ready for operation.
If three position season switch is in the “summer” position and the three position blower switch is in the “on“ posi-
tion, and the entering air temperature is above the freezestat setting, power is supplied to the blower motor starter.
Blower motor will run if blower motor overloads are not tripped. Heating coil is inoperative. System white light on
remote control panel will be on if air proving switch is closed. Optional clogged filter light on remote control panel
will be operational if a blocked intake or clogged filter situation occurs.
Summer Operation
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