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GAS-FIRED BOILER Boiler Manual
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 8-1) in the electrical
junction box. Caution should be used to
ensure neither of these terminals become
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
1. There is no indirect sensor connection
required if an indirect water heater is not
used in the installation.
2. The MOD CON 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 MOD CON 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 settable set
point by more than the user selectable 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 8-1) in the electrical junction
box. Caution should be used to ensure
neither of these terminals become connected
to ground.
I. OPTIONAL 0-10 VOLT BUILDING
CONTROL SIGNAL
1. A signal from a building management system
may be connected to the MOD CON 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 either the set point temperature or the
heat output of the MOD CON Boiler. The
control interprets the 0-10 volt signal as
follows. When the signal is between 0 and 1
volt, the MOD CON Boiler will be in stand by
mode, not firing. When the signal rises above
1 volt, the MOD CON Boiler will ignite. As the
signal continues to rise towards its maximum
of 10 volts, the MOD CON boiler will increase
either in set point temperature or firing rate
depending on the setting of parameter 17 in
the installer menu. See Part 11 for details on
the setting of parameters 16 and 17 for this
option.
2. Connect a building management system or
other auxiliary control signal to the terminals
marked 0-10 VOLT + and 0-10 VOLT – in the
electrical junction box (shown in figure 8-1)
Caution should be used to ensure that the 0-
10 VOLT + connection does not become
connected to ground.
J. OPTIONAL HIGH GAS PRESSURE
SWITCH
1. If an optional high gas pressure switch is
used, it should be installed on the outlet side
of the gas valve. This is normally closed and
will open if the pressure goes above 1” w.c.
on the outlet side.
2. Locate the two pigtails hanging from the
electrical box inside of the boiler cabinet.
Remove and discard the jumper plug from
one of the unused pigtails.
3. Connect the high gas pressure switch to the
pigtail that you removed the jumper plug
from.
PART 8: FIELD WIRING (CONTINUED)
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