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NORA Oilheat Technicians Manual

revisions have wires, while others have spade connectors. Series 4 and later controls have added safety features. If a Series 4 control detects flame eight seconds into “valve on delay” or 30 seconds into “burner motor-offdelay,” the control will go into lock out. This is to prevent poor starts and shutdowns due to bad oil valves. This means that these controls CANNOT be operated without an oil valve. If the fuel unit has to be replaced, you MUST use one with either an integral or external oil valve. It also means that if you are replacing an earlier control with a Series 4 or later control, you cannot simply “cap off” the violet and/or black wires as you could with earlier revisions. There is also a series 5 control. See Beckett’s website for details. Sequence of operation Currently, the most sophisticated Honeywell R7184 is the U model. Let’s take a look at how it operates. Standby: When a call for heat is initiated, there is a 2 to 6 second delay while the control performs a safe start check. If no flame is sensed and all internal 11-22 16 Primary Controls Chapter 11 Primary Controls conditions are correct, the control enters “valve on delay” mode—and the ignition and motor are powered for 15 seconds. Trail for ignition: Then the control goes into “trial for ignition.” The oil valve is powered and opens. Flame should be established within the “trial for ignition” timing of 15 or 30 seconds. If no flame is sensed by the end of “trial for ignition,” the control goes into lockout and must be manually reset. The dry alarm contacts close and complete the circuit to activate any remote alarm that is connected. Carryover: Once the flame is established, the ignition remains on for 10 seconds to ensure flame stability, then shuts off. The burner will then run until the call for heat is satisfied, at which time the power to the oil valve will shut down. Burner motor off delay: The motor will continue to operate from 30 seconds to 8 minutes depending on how the dip switches are set. Once this “burner motor-off delay” cycle has been completed, the control returns to standby mode. Honeywell—continued


NORA Oilheat Technicians Manual
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