SECTION II: OPERATING AND SERVICE INSTRUCTIONS
A.Intermittent Circulator Operation
1.ROOM THERMOSTAT CLOSES
2.CIRCULATOR MOTOR ENERGIZED
a.As the thermostat closes its contacts, a low voltage circuit (24V.) is completed to the bimetal heater in the circulator relay (24A51). After
a time delay of 15 seconds, the main contacts (120V.) of the circulator relay close to start the circulator.
3.HEATING ELEMENT #1 ENERGIZED
a.Simultaneous with the completing of the circuit for the circulator relay, two additional circuits are completed.
b.The first circuit is for the Heating Element Relays which pull in immediately and the second is for the bimetal heater in the #1 Heating Element Sequencer (24A54).
c.These two circuits will be energized only if the boiler is not “OFF” on limit.
d.After a time delay of 45 seconds (30 seconds after the circulator has started) the main and auxiliary contacts of the #1 Sequencer close; the main contacts (240V.) energizing heating element #1 and its pilot light (located at the bottom of the side panel), the auxiliary contacts (24V.) energizing the bimetal heater in the #2 Heating Element Sequencer.
4.HEATING ELEMENT #2 ENERGIZED
a.45 seconds after bimetal heater in #2 Heating Element Sequencer is energized, its main contacts (240V.) and auxiliary contacts close; the main contacts energizing heating element #2 and its pilot light (3rd lowest in the boiler), the auxiliary contacts (24V.) energizing the bimetal heater in the #3 Heating Element Sequencer.
5.HEATING ELEMENT #3 ENERGIZED
a.45 seconds after bimetal heater in the #3 Heating Element Sequencer is energized, its main contacts and auxiliary contacts close; the main contacts (240V.) energizing heating element #3 and its pilot light (2nd lowest in the boiler), the auxiliary contacts (24V.) energizing the bimetal heater in the #4 Heating Element Sequencer.
6.HEATING ELEMENT #4 ENERGIZED
a.45 seconds after bimetal heater in #4 Heating Element Sequencer is energized, its main contacts and auxiliary contacts close, the main contacts (240V.) energizing heating element #4 and its pilot light (highest in the boiler) – nothing is connected to the auxiliary contacts.
7.ROOM THERMOSTAT OPENS
8.HEATING ELEMENTS DE-ENERGIZED
When the thermostat is satisfied and opens its contacts, the low voltage circuits to the Heating Element Relay and the Heating Element Sequencers are broken. The Heating Element Relays
9.CIRCULATOR MOTOR DE-ENERGIZED
Simultaneous with the breaking of the low voltage circuit to the Heating Element Sequencers is the breaking of the low voltage circuit to the Circulator Relay by the opening of the thermostat contact. After a time delay of 90 seconds after all Heating Elements are “off” the bimetal heater opens the main contacts in the Circulator Relay thus stopping the circulator. When the boiler is zoned with circulator and switching relays as illustrated in Figure 6 on Page 8 the circulator switch must be in the “constant” position; therefore the circulator will not have any delay when the thermostat(s) closes or opens its contacts.
B.Continuous Circulator Operation
If the Circulator Switch (located in the control portion of the Boiler Jacket) is placed in the “CONT.” position, the Circulator will run continuously and the Heating Elements will sequence as in steps
C.Dual Limit Operation
The Dual Limit Control consists of two independently adjustable temperature limits. The left hand adjustment is for the safety limit and should be set initially for 220°F. The lower right hand adjustment is for the operating limit and should be set for 210°F with a differential setting (upper right hand adjustment) of 10º. These adjustments may be varied to suit the individual installation, with minimum of 10° difference between the limit settings. If the setting of the operating Limit or the safety limit is reached, the Heating Elements only will be
WARNING
Before installation of the boiler is considered complete, the operation of the boiler controls should be checked, particularly the Operating & Safety Limit Controls.
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