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LP- 428 REV. 9.2.14
E. LOW VOLTAGE CONNECTIONS
1. All low voltage cables should enter the electrical junction box through the provided knock out holes shown in Figure 24.
2. Connect all low voltage field devices in the low voltage terminal strip located in the electrical junction box (shown in Figure 27).
F. THERMOSTAT
1. Connect the room thermostat to the terminals marked THERMOSTAT in the electrical junction box (shown in Figure 27) of the
bottom boiler. Alternately, any dry contact closure across these terminals will cause the boiler system to run. Caution should be taken to
ensure neither of the terminals becomes connected to ground.
2. Mount the thermostat on an inside wall as centrally as possible to the area being heated, but away from drafts or heat producing
devices such as television sets that could influence the ability of the thermostat to measure room temperature.
3. If the thermostat is equipped with an anticipator and it is connected directly to the Mod Con boiler, the anticipator should be set at .1
amps. If the thermostat is connected to other devices, the anticipator should be set to match the power requirements of the device it is
connected to. See the instruction manual of the connected devices for further information.
G. OUTDOOR SENSOR
1. There is no connection required if an outdoor sensor is not used in this installation.
2. If using an outdoor sensor, connect wires for sensor to the terminals marked OUTDOOR SEN (shown in Figure 27) in the electrical
junction box of the bottom boiler. Caution should be used to ensure neither of these terminals becomes connected to ground.
3. Use a minimum 22 AWG wire for runs of 100 feet or less and minimum 18 AWG wire for runs of up to 150 feet.
4. Mount the outdoor sensor on an exterior surface of the building, preferably on the north side in an area that will not be affected by
direct sunlight and will be exposed to varying weather conditions.
H. INDIRECT SENSOR (TOP BOILER CONNECTION)
1. There is no connection required if an indirect water heater is not used in this installation.
2. The boiler will operate an indirect fired water heater with either a thermostat type aquastat installed in the indirect tank, or an HTP
7250P-325 tank sensor. When a tank sensor is used, the control will automatically detect its presence and a demand for heat from the
indirect water heater will be generated when the tank temperature falls below the user selected set point by more than the user selected
offset. The demand will continue until the sensor measures that the indirect water heater temperature is above the set point.
3. Connect the indirect tank sensor (7250P-325) to the terminals marked DHW SENSOR (shown in Figure 27) in the electrical junction
box of the top boiler.
Caution should be used to ensure neither of these terminals becomes connected to ground.
NOTE: If sensor wires are located in an area with sources of potential electromagnetic interference (EMI), the sensor wires should be
shielded, or the wires routed in a grounded metal conduit. If using shielded cable, the shielding should be connected to the common
ground of the boiler.
Failure to use the correct sensor may result in tank temperature being either above or below set point, and could result in decreased
performance, substantial property damage, or heightened risk of injuries due to scalds.
I. OPTIONAL 0-10 VOLT BUILDING CONTROL SIGNAL
1. A signal from a building management system may be connected to the boiler to enable remote control. This signal should be a 0-10
volt positive going DC signal. When this input is enabled using the installer menu, a building control system can be used to control
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