Bradford-White Corp BWCV SECTION Operating Instructions, Sequence of Operation, Bradford White

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Page 20 Bradford White

Most of the time, the number of stages from the external control will match the number of stages on the heater. However, in some instances, the controller will not have enough staging capability to work with all of the stages on a heater (for instance, using an 8-stage external control with four 4-stage Copper Brute II units.) In these instances, it is very important to follow the instructions in this section. Figure 9 shows how to combine stages on the heater for those instances when the external controller cannot control all the stages available on the heater.

Note: The only time heater stages should be jumpered is when the heater has an external control, and the heater is used in Mode 6. In all other modes, when the heater controls its stages, the terminals shown in Figure 9 must NOT be jumpered.

SECTION 6.

Operating Instructions

6.1Sequence of Operation

A call for heat can be initiated either

automatically (“auto mode”) under thermostatic control by the heater temperature control, or by an external contact closure (“manual mode”).

In auto mode, the heater will fire its stages of input to maintain a target temperature programmed into the temperature control. The controller can be programmed per section 6.2.

In manual mode, an external control will control the heater stages, as long as the heater control is set to mode 6, and the auto/manual switch (located inside the control compartment) is set to manual.

The amber “Ready” light on the front panel indicates that the control system is energized. Upon a call for heat, the green “Heat” indicator on the front panel will light.

If the unit is pump-mounted, the pump will be energized. The pump terminals on the field-wiring terminals strip will energize a field pump that is properly interlocked with the heater. The green “Pump” indicator on the front panel will light.

Once the water flow switch makes, and if all of the safety interlocks are closed, the ignition module will energize the blower(s) for a 15-second pre-purge, followed by a 20-second period to allow the ignitor to heat.

Energizing the blower pressurizes the air box (which supplies air to the burners) and closes the normally-open contact(s) of the airflow pressure switch(es). This allows the ignition module to proceed with the ignition sequence.

The blocked flue pressure switch senses the pressure in the plenum. It will interrupt the airflow sensing circuit if this pressure exceeds a maximum value. If airflow is not proven, the ignition module will lockout.

The ignition module checks that the ignitor current has reached a minimum value and energizes the gas valve at the end of the ignitor heating period. The green “Stage 1” indicator on the front panel will light, indicating that the stage 1 gas valve is open.

After a 4-second trial for ignition, the ignitor switches off, and unless a flame is detected by the flame sensor, the gas valve will close and the ignition module will either attempt ignition again (up to three times) or will lockout (if the optional lockout ignition module is used).

If flame is sensed, the burner will continue to fire as long as there is a call for heat. In Auto mode, additional stages are delayed by a minimum of 60 seconds (less prepurge and ignitor warm-up time) and once energized, must fire for at least 30 seconds. The request for additional stages is indicated on the control display, and the energizing of additional burner stages is indicated by front panel lights.

If there is a subsequent loss of flame signal, the burner will attempt re-ignition up to three times (only once if optional lockout ignition module is used.)

When the call for heat is satisfied, the gas valve(s) closes and the blower(s) continues to run for 30 seconds. The pump will continue to run for a minimum of 20 seconds and up to a programmable maximum of 10 minutes.

If a call for heat is prevented from being satisfied either by a safety interlock or due to an ignition lockout, the red “Service” indicator on the front panel will light. To reset the standard ignition module,

the reset button on the module must be pressed. Interrupting power to this module will not reset the lockout.

The Copper Brute II 1000 - 2000 models have two ignition modules that control different burners. If one module should fail for any reason, the remaining

module can operate its burner(s) independently.

Important: The installer is responsible for identifying to the owner/operator the location of all emergency shutoff devices.

WARNING

Do not use this appliance if any part has been under water. Immediately call a qualified service technician to inspect the appliance

and to replace any part of the control system and any gas control that may have been

under water.

6.2 Programming the Temperature Control

The same temperature control is used on all versions of the Copper Brute II (in two-and four-stage configurations), providing maximum flexibility to meet the needs of any system. Before start-up, you must program the temperature control for the type of system