Burnham 81433101R16-1/10 manual Electrical and Sequence of Operations

V. Electrical and Sequence of Operations

A. ELECTRICAL

1.Install wiring and ground boiler in accordance with requirements of authority having jurisdiction, or in absence of such requirements the National Electrical

Code, ANSI/NFPA 70, and/or the CSA C22.1 Electric Code.

2.A separate electrical circuit must be run from the main electrical service with an over-current device/disconnect in the circuit. A service switch is recommended and may be required by some local jurisdictions.

3.Wiring should conform to Figures 15 and 15A.

4.Thermostat heat anticipator setting = 0.3 amp.

B. SEQUENCE OF OPERATIONS

1.General. A call for heat by the thermostat energizes the L7248C limit control which in turn energizes the R7184P primary control to turn on the burner. The circulator will operate as long as there is a call for heat. If the call for heat is not satisfied and the high limit setting is reached, the circulator will continue to operate, and the burner will stop until the high limit circuit is closed by a drop in boiler water temperature.

2.L7248C Combination Limit control.

The switching action within the L7248C control has one setting, the high limit. The switching relay is controlled by the low voltage room thermostat. On

acall for heat, the relay contacts close to complete the line voltage circulator circuit and also the burner circuit if the boiler water temperature is below the high limit setting. The high limit switch shuts off the burner if boiler water temperature exceeds the high limit setting. See Figure 14.

3.R7184P Oil Primary Control.

The R7184P operates the oil burner motor, solenoid oil valve, and the electronic ignitor in response to a call for heat from the L7248C limit control.

a.A call for heat will energize the burner motor and electronic ignitor.

b.After a 15 second pre-purge period, in which time a draft is established in the flueways, the oil valve is opened.

c.If the burner ignites within 15 seconds from the time the oil valve opens and the CAD cell senses a flame, the electronic ignitor is de-energized and the burner will operate until the call for heat is satisfied or the setting of the high limit is reached.

d.A manual reset button is provided to reset the safety switch after lockout.

e.When the call for heat ends, or the CAD cell fails to sense a flame, the oil valve will close.

The combustion blower will continue to operate for a postpurge period of approximately two (2) minutes.

4.CAD Cell.

The Beckett AFII burners used on the LEDV Series are supplied with a C554A Cadmium Sulfide (cad cell) Flame Detector to monitor the burner flame and shut down the burner on ignition failure or on flame failure during the run cycle. On either failure, the manual reset button on the R7184P will be tripped.

Figure 14: L7248/L7224 Setpoint and Differential

Switching Action

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