Weil-McLain 4 Series Manual page 98

®
Series 4
Field wiring — advanced
Add itional limits
1. The U-Control allows connection of external limit controls,
both for manual reset and for automatic reset operation of the
U-Control.
external limits across P13, terminals 1 and 2 if the U-Control is
to require manual reset when a limit opens, even if the limit re-
closes. (Remove the factory jumper when using these terminals.)
The U-Control will lockout when a limit in its manual
reset circuit opens. The U-Control activates its alarm
terminals and shuts the boiler down until an operator
manually resets the U-Control (as explained in this
manual). This reset function can be done by a home-
owner or a service technician.
external limits across P13, terminals 3 and 4 if the U-Control is to
reset automatically when the limit circuit closes after a limit con-
dition. (Remove the factory jumper when using these terminals.)
Remote operation/modulation
1. The U-Control module provides terminals to input a remote
0–10 VDC operating signal. This can be provided by a separate
controller if the boiler is confi gured as Type 4 (SHADOW boiler
mode).
2. Connect the 0–10 VDC signal positive terminal to P15 terminal 6,
and the signal common to terminal 5.
3. When receiving a remote operating signal, the boiler starts when
the signal exceeds 1.0 VDC (and shuts off if the signal drops
below 0.5 VDC). The boiler remains at low fi re until the signal
exceeds 2.0 VDC. Between 2.0 and 10.0 VDC, the boiler fi ring rate
increases with the signal value, reaching full input at 10.0 VDC.
4. The U-Control continues to monitor boiler temperatures, based
on the values set up under Priority 1 operation. See the following
section for details.
Additional heat demand option
1. The U-Control module can be set up to activate another heat
source using its additional heat demand dry contracts (P16,
terminals 6 and 7).
2. Connect these terminals to call for heat from the other heat
source. (See the following section to program the boiler to ac-
tivate the other source, either as the primary or secondary heat
source.)
Alarm contacts
(low voltage ONLY)
1. The U-Control's alarm dry contact (P16, terminals 4 and 5) closes
when the boiler enters lockout.
2. Connect these terminals for remote alarm notifi cation.
Multiple boiler wiring options
1. The U-Control can be programmed to sequence multiple boilers
or operate/modulate in tandem from a 0–10 VDC source gener-
ated by the lead boiler or from a remote controller.
2. See "ADDITIONAL HEAT DEMAND," page 99 for recommended
wiring.
98
gas-fired water boiler — Boiler Manual
— Connect
— Connect
Outdoor temperature sensor
1. The U-Control provides programmable options when
using an outdoor temperature sensor. This sensor is
supplied with the boiler, and can be used if desired (not
required). See the following section for outdoor tem-
perature options.
2. Mount the outdoor sensor on an exterior wall, shielded
from direct sunlight or fl ow of heat or cooling from
other sources.
3. Connect the sensor leads to P10, terminals 1 and 2, as
shown in the wiring diagrams. Thermostat wire can be
used to connect the sensor.
System supply & return temperature
sensors
(see Figure 4, page 11 for placement of sensors)
1. The boiler is also shipped with two strap-on temperature
sensors, intended for system supply and return.
2. These sensors can be attached to piping up to 3-inch
diameter.
3. Thermostat wire can be used to connect these sensors.
4. The system supply temperature sensor allows the U-Con-
trol to regulate temperature in the system main piping.
5. Locate the supply sensor at least six pipe diameters, but
no further than 3 feet, downstream from the boiler con-
nection to the main to ensure adequate mixing.
6. The system return sensor allows the U-Control to moni-
tor and display system return temperature.
7. For multiple boiler applications, install a system supply
temperature sensor and system return sensor wired to
the LEAD boiler.
8. The U-Control also compares the system return tem-
perature with the system supply temperature. Should the
return temperature ever exceed the supply temperature,
the U-Control knows there is likely a sensor failure and
will report this problem on the display.
(continued)
Part number 550-100-400/0119