Product Overview

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1) 120 Volt Wiring - The boiler should be provided with its own 15A branch circuit with fused disconnect. All 120 volt
connections are made inside the junction box on the left side of the boiler. Remove the transformer to gain access to this
box (also see Figures 16 and 17):
• Hot (“black”) - Wire nut to black transformer lead
• Neutral (“white”) - Wire nut to white transformer lead
• Ground (“green” or bare) - Ground screw inside junction box.
2) Thermostat Wiring - Follow thermostat manufacturer instructions. To insure proper thermostat operation, avoid
installation in areas of poor air circulation, hot spots (near any heat source or in direct sunlight), cold spots (outside
walls, walls adjacent to unheated areas, locations subject to drafts). Provide Class II circuit between thermostat and
boiler. Connect thermostat wire leads to the blue transformer lead and brown relay lead inside the junction box. Set the
heat anticipator to 0.2A.
Feeder Wiring for Boilers Equipped with Hydrolevel CG400A Low Water Cut-offs
1) Using Hydrolevel VXT-24 TWO-WIRE feeder - Do not alter factory boiler wiring. Connect VXT-24 to CG400A as
follows:
• Connect the BLACK lead on the feeder to terminal A on the LWCO
• Connect the WHITE lead on the feeder to terminal 2 on the LWCO
2) Using Hydrolevel VXT-24 THREE-WIRE feeder - Do not alter factory boiler wiring. Connect VXT-24 to CG400A as
follows:
• Connect the BLACK lead on the feeder to terminal 1 on the LWCO
• Connect the WHITE lead on the feeder to terminal 2 on the LWCO
• Connect the RED lead on the feeder to terminal A on the LWCO
3) Using McDonnell & Miller WF2-U-24 feeder - Do not alter factory boiler wiring. Connect WF2-U-24 to CG400A as
follows:
• Connect terminal W on the feeder to terminal A on the LWCO
• Connect terminal N on the feeder to terminal 2 on the LWCO
• Connect terminal H on the feeder to terminal 1 on the LWCO
CAUTION
Do not attempt to connect a McDonnell & Miller model #101A feeder, or other feeder without a delay, to a CGS-C boiler
equippedwithaHydrolevelCG400lowwatercutoff.Doingsocoulddestroytheboilertransformerand/oroodthe
system.
WARNING
All wiring and grounding must be done in accordance with the authority having jurisdiction or, in the absence of such
requirements, with the National Electrical Code (ANSI/NFPA 70)
X. Electrical