Dunkirk XEB-3 Installation, Operation & Maintenance Manual page 23

All electrical work must conform to local codes as well as the Na-
tional Electrical Code, ANSI/NFPA-70, latest revision. In Canada,
electrical wiring shall comply with the Canadian Electrical Code,
CSA-C22.1.
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Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and dangerous
operation. Verify proper operation after servicing.
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Electric Power Supply
Run a separate 120 volt circuit from a separate over current protec-
tive device in the electrical service entrance panel. This should be a
15 ampere circuit. Locate a shut-off switch at the boiler. It must be
turned offduring any maintenance. Connect 120 volt power supply
to aquastat terminals L1 (HOT) and L2.
The boiler, when installed, must be electrically grounded in accor-
dance with the requirements of the authority having jurisdiction or,
in the absence of such requirements, with the National Electrical
Code, ANSI/NFPA No. 70 - latest revision. Run a 14 gauge or heavier
copper wire from the boiler to a grounded connection in the service
panel or a properly driven and electrically grounded ground rod.
Install Your Thermostat
The thermostat location has an important effect on the operation of
your boiler system. BE SURE TO FOLLOW THE INSTRUCTIONS
INCLUDED WITH YOUR THERMOSTAT. Locate the thermo-
stat about five feet (5') above the floor on an inside wall. It may be
mounted directly on the wall or on a vertically mounted outlet box.
It should be sensing average room temperature.
Behinddoors
Corners &
alcoves
Concealed pipes
Fireplace
TV sets
Radios
Lamps
Direct sunlight
Kitchens
Concealed pipes
or ducts
Stairwells- drafts
Doors- drafts
Unheated room on
other side of wall
Set heat anticipator at .2 amps. The 24 volt thermostat connects
to aquastat terminals T and T.
Sequence of Operation - Refer to Figure 13
1. Thermostat calls for heat, powering the 1K relay coil and closing
contacts 1K1 and 1K2.
2. Circulator pump is powered through terminals C1 and C2.
3. Induced draft blower and transformer primary are powered
through terminals B1 and B2.
4. When blower gets up to speed and blower suction pressure
reaches pressure switchset point, pressure switch contacts close
sending 24 volts to intermittent pilot control from transformer
secondary.
5. Pilot gasvalve opens and spark initiates to light pilot burner.
6. When pilot flame is proven, spark drops out.
7. Main gas valve opens and pilot burner ignites main burners.
8. If boiler water temperature reaches high limit set point, high
limit contacts B-R open, cutting power to blower and intermit-
tent pilot control. Burners extinguish and blower stops. Circula-
tor pump continues to run as long as the thermostat continues
to call for heat. When boiler water temperature drops past the
high limit set point and through the differential, high limit
contacts B-R close,repeating steps 3-7.
9. If venting systembecomes blocked, blower suction pressure will
drop below the pressure switch set point, opening the pressure
switch contacts and cutting power to the intermittent pilot con-
trol. Burners will extinguish, but blower will remain powered
as long as the thermostat continues to callfor heat. If venting
system clears, steps 4-7 will repeat.
10. Thermostat is satisfied, ending callfor heat. Relaycoil 1Kis de-
energized,opening 1K1and 1K2contacts. Burners extinguish.
Blowerand circulator pump stop.