Weil-McLain 550 MBH Nstallation And Operation Manual page 53

®
SlimFit Series 3
Field wiring
1. Two strap-on temperature sensors are shipped with each boiler. Attach one
to the system supply piping and the other to the system return piping. For
piping larger than 5 inch diameter or nonmetallic piping, using immersion
sensors will provide faster response. See
parts section for available immersion sensors.
2. Locate the supply sensor at least six pipe diameters, but no further than 3
feet, downstream from the boiler connection to the main to ensure adequate
mixing.
3. Supply sensor – wire between P14 #1 and #2 (common).
4. Return sensor – wire between P14 #3 and #2 (common).
5. Thermostat wire can be used to connect these sensors.
6. The Control compares the system return temperature with the system supply
temperature. Should the return temperature ever exceed the supply tempera-
ture, the Control knows there is likely a sensor failure and will report this
problem on the display.
All heating systems shown in this manual require the System Sup-
ply and Return sensors to be installed for proper control function.
System will not properly provide heat if sensors are not installed
according to these instructions.
F. Outdoor temperature sensor –
1. The control provides programmable options if using an outdoor tempera-
ture sensor. This sensor is supplied with the boiler.
2. Mount the outdoor sensor on an exterior wall, shielded from direct sunlight
or flow of heat or cooling from other sources.
3. The wire outlet on the sensor must be oriented DOWN to prevent water
entry.
4. Connect the sensor leads to the terminal shown at right and in the wiring
diagrams (see Figure 52, page 60). Thermostat wire can be used to connect
the sensor.
Part number 550-100-168/0516
COMMERCIAL CONDENSING GAS
(SlimFit control module, left side)
SlimFit
boiler manual replacement
OPTIONAL
(SlimFit control module, left side)
—
-
FIRED WATER BOILER
(continued)
–
REQUIRED
Strap to supply & return piping
See Figure 52, page 60 for details
See Figure 52, page 60 for details
Boiler Manual
53