Specifications

44
LP- 276 REV. 9.4.14
PART 7 – FIELD WIRING
ELECTRICAL SHOCK HAZARD - Turn off electrical power supply at service entrance panel before making any electrical connections.
Failure to do so can result in severe personal injury or death.
Wiring must be N.E.C. Class 1. If original wiring supplied with the boiler must be replaced, use only UL Listed TEW 105
o
C wire or
equivalent. Boiler must be electrically grounded as required by National Electrical Code ANSI/NFPA 70 – Latest Edition.
In order to ease future servicing and maintenance, it is advised to label all wires. Wiring errors can cause improper and dangerous
operation. Failure to follow these instructions could result in property damage or personal injury.
A. INSTALLATION MUST COMPLY WITH:
1. National Electrical Code and any other national, state, provincial or local codes or regulations.
2. In Canada, CSA C22.1 Canadian Electrical Code Part 1, and any local codes.
B. FIELD WIRING TERMINATIONS
All connections made to the boiler in the field are done inside the electrical junction box located on the side of the unit. The electrical
junction box is located on the right side of the Mod Con 300, and the left side of both the Mod Con 500 and 850. Multiple knockout loca-
tions are available to route field wires into and out of the electrical junction box.
C. FIELD WIRING CONSIDERATIONS
Check water chemistry section for acceptable levels. If water chemistry is acceptable, pumps may be wired directly to pump terminals.
If water chemistry levels are too high, you must wire pumps to line voltage to run continuously to prevent lime buildup.
Pumps
The Mod Con VWH application requires a circulator pump for each boiler. Circulator pumps
can be wired directly to the controller as shown in Figure 24 or wired directly to line voltage
for continuous operation. Only wire the circulator pump to the controller if a tank sensor or
mechanical control can be mounted to the storage tank, otherwise circulator pumps must be
wired to run continuously.
The circulator pump wired to the boiler control will have a default program of a 5 minute post
purge to provide stabilization and post cleaning of the heat exchanger. The boiler control is
capable of supplying 120 volts at up to 3 amps to run the circulator pump. If using a larger
circulator pump requiring more than 3 amps or higher voltage, an external motor starter,
sized appropriately for the pump motor, must be used. This starter should have a 120 VAC
coil. If a starter with a 120 VAC coil is used, it can be wired directly to the appropriate pump
terminals as shown in Figure 24.
Tank and Sensor Connections
When the Mod Con VWH is used in a single boiler installation, it is recommended to use a
sensor (7250P-325) placed in a well in the storage tank for best temperature control. If
multiple tanks are used in the installation, it is recommended to put a mechanical aquastat in
each tank and wire them in series to provide temperature control of the tanks. (See Piping Diagrams in Part 4, Section I for reference.)
The control in the Mod Con VWH will read either the temperature of the tank sensor or the status of the aquastats, and cause the boiler
to run until the water temperature of the tank(s) meets the desired set point.
If a sensor or aquastat cannot be placed directly in the tank, then one sensor should be used on the pipe carrying water from the
tank(s) to the boiler. To minimize temperature loss in the piping, this sensor should be placed as close to the tank(s) as possible. The
To avoid electrical shock, turn off all power to the appliance prior to opening an electrical box within the unit. Ensure the power remains
off while any wiring connections are being made. Failure to follow these instructions could result in component or product failure,
serious injury, or death. Such product failure IS NOT covered by warranty.
Figure 23