PB Heat Gas Boiler manual Electrical, A.Wiring, B.Sequence Of Operation

ELECTRICAL

6. ELECTRICAL

Install all electrical wiring in accordance with the National Electrical Code, ANSI/NFPA 70, and local requirements.

c)An example of this wiring using a Honeywell R845A relay is shown in Figure 6.2

NOTICE

This unit when installed must be electrically grounded in accordance with the requirements of the authority having jurisdiction or, in the absence of such requirements, with the current edition of the National Electrical Code, ANSI/NFPA 70.

A.WIRING

1.Refer to Figures 6.1 for connecting the power supply to the boiler.

Figure 6.1: Wiring Connections to Boiler Junction Box

2.Connect boiler to a 110 volt, single phase, 60 hertz electrical supply line with a fused disconnect switch. The boiler is fused for a load of 6.3 amperes.

3.The boiler electrical connection is located on the left side of the boiler in the junction box which houses the service switch.

4.Wire the burner service switch in the hot line to the boiler as shown in Figure 6.1.

5.Make sure to maintain correct polarity on the incoming power supply wires. If polarity is reversed, the boiler control will not sense the main burner flame.

6.Connect the ground wire from the incoming power supply to the green ground screw in the junction box. Also, the boiler ground should be connected to this screw.

7.Figure 6.1 shows connections to system circulator.

a)The maximum current load for the circulator circuit is 4.0 amperes.

b)For loads greater than 4.0 amps, isolate the circulator using a switching relay.

Figure 6.2: Wiring Circulator with R845A Switching Relay

8.The thermostat connections are shown in Figure 6.1 or 6.2. The setting for the thermostat anticipator is

0.56amps.

9.The boiler control board and factory wiring are shown in figure 6.3.

B.SEQUENCE OF OPERATION

1.System Power-Up:

a) When power is first applied to the boiler, the control will initially run through a self-diagnostic routine. The interface unit shows the system supply temperature.

b) Next, it will power the combustion air fan for a 10 second purge cycle.

c) Finally the combustion air shuts down and if there is no call for heat the control board enters a standby mode.

2.Heating Cycle:

a) When the thermostat calls for heat (closing the contact between the two gray [TT] wires) and the boiler control senses a supply temperature lower than the set point by more than the differential, the boiler initiates a heating cycle.

b) The control then powers the combustion air fan at the speed prescribed for the particular boiler model and performs a 6 second pre-purge of the combustion chamber.

c) 0.5 second before the pre-purge is complete power is applied to the spark igniter.

d) Once the pre-purge cycle is complete, the fan speed decreases to the programmed ignition speed.

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