Bradford-White Corp BRHHH, BRHHV Troubleshooting, Sequence of Operation, Normally Open Vent Valve

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8.Clean the heat exchanger: A light accumulation of soot or corrosion on the outside of the heat exchanger can be easily removed. Use a wire brush to remove loose soot and scale from the heat exchanger. Do not use water or compressed air for cleaning.

9.NOTE: While the heat exchanger is out of the unit, inspect the firewall refractory insulation blocks for cracks, wear and breakage. Replace if necessary.

10.Inspect the inside of the copper tubes for scale buildup. Scale can build up on the inner surface of the heat exchanger tubes, which can restrict water flow. If the tubes show signs of scaling, clean the internal surface. Bradford White offers a tube cleaning kit, part number R2000700.

11.Reassemble in the reverse order.

If heat exchanger removal is necessary, consult the factory for instructions.

NOTE: The Warranty does not cover damage caused by lack of required maintenance, lack of water flow, or improper operating practices.

The condensing (stainless steel) heat exchanger is not in the firing chamber, so it will not experience sooting. If there is fouling on the stainless steel heat exchanger, or if it needs to be changed, contact the factory.

7.2.17Normally Open Vent Valve

Some Brute Magnum models provide a

normally open vent valve for installations with IRI code requirements. The valve opens when power is removed from the safety valves. And the valve closes when the safety valves are powered. See Section 3.1 item #4 for installation instructions.

7.2.18Motorized Safety Valve

Control packs B and E have an additional

motorized safety valve. This valve is powered open at the same time as the safety valve. To remove the valve actuator, shut off the 120V power and the gas shutoff valve. Remove the right side, or front panel.

Disconnect the 120V wires from the actuator. Remove the valve actuator by taking out the four screws, and pulling the actuator out. Re-install in reverse order. Turn on gas shutoff valve and 120V power and check appliance operation and tightness of gas valve connections.

The gas valve body will rarely have to be

removed. If there is a valve problem, and it has been determined the actuator is working properly, the gas valve body may need to be replaced. To remove the gas valve body, shut off 120V power and the gas shutoff valve. Remove the right side and front panels. Remove the valve actuator. Unscrew the valve body from the gas train. After the valve has been removed, replace with a new valve in reverse order. Turn on gas

shutoff valve and 120V power and check appliance operation and tightness of gas valve connections.

7.2.19 Gas Pressure Switches

The high and low gas pressure switches are 24V manual reset switches that act to cut power to the gas valves if the gas pressure is too low or too high for proper operation. The gas pressure switches used are integrally vent limited, and do not require venting to atmosphere. To remove a switch, remove the screw on the plastic housing and pull the clear cover off. Disconnect the two wires from the screw terminals. Twist the switch off the pipe nipple. Reassemble in reverse order. For natural gas, set the low gas pressure switch to 3" w.c. For propane, set the low gas pressure switch to 5" w.c. For natural and propane, set the high gas pressure switch to 14".

Section 8

TROUBLESHOOTING

8.1Sequence of Operation

The Brute Magnum appliance is a cold start

appliance that should start only on a call for heat from a tank aquastat, room thermostat, zone valve end switch or other space temperature control device.

1.Upon a call for heat,

(a)The internal pump will start.

(b)The blower will begin a 15 second pre- purge.

2.Following the prepurge cycle the hot surface ignitor will heat and will begin a 7 second trial for ignition. The unit is allowed three attempts for ignition.

3.The gas valve will then be energized and low- fire (50% of full fire) ignition will occur. The unit will remain in a low-fire start-up period for 15 seconds.

4.After the low-fire start time is over, the unit will be in normal operation firing rate and will modulate based on the heating load via the temperature controller settings and readings.

5.The mixing system control will sense the water temperature entering the copper heat exchanger, and will change the positions of the mixing valves to divert enough hot water from the copper heat exchanger outlet back to its inlet to keep the inlet at a minimum 140°F (60°C). Therefore, when the return water temperature is 140°F (60°C) or lower, the outlet temperature will be 160-165°F (71-74°C). With return temperatures greater than 140°F (60°C), the temperature rise across the Brute Magnum is 20- 25°F (11-14°C), when the Brute Magnum is at high firing rate.