LAARS M4-Ext - Installation Manual - Manual (Page 10)

10
iNSTALL THE SENSORS
SYSTEM SENSOR (HSS) iNSTALLATiON
• Only use a Standard Brass Tube sensor (CA002400 or equivalent).
• The sensor wires can be extended up to 500' using a shielded 2-conductor cable
(Belden #8760 or equivalent). Do not ground the shield at the sensor but at the
panel using one of the terminals marked with an “O”.
• Do not run sensor wires in conduit with line voltage wiring.
• Install a 3/8"ID 1/2"NPT immersion well (CA002500 or equivalent).
• Insert the sensor in a well approximately 10' feet past the last boiler on the
common supply header but before any major takeoffs.
• The sensor must be located where it sees the output of all the boiler stages. If a
boiler is piped so that the sensor does not see its output, the M4-CNC will not
sequence the boilers correctly.
• The sensor can also be installed on the return to the boilers after all major returns
and before any boiler. However, when setting the reset ratio and the offset, the
user must consider the temperature drop across the building loop.
Immersion Well
3/8" ID 1/2" NPT
Heating System
Sensor
Common Supply Pipe
Sensor Probe
Immersion Heating System Sensor
Shield
Common Supply Pipe
Sensor Probe
Strap-On Heating System Sensor
Shield
Pipe Insulation
Connect
To control
ALERT
If the System Sensor can not sense the
correct water temperature, the M4-CNC
will not provide comfortable heat levels.
OUTdOOR SENSOR iNSTALLATiON
• Only use the Laars sensor included with the unit (CA006500).
• Locate the sensor in the shade on the north side of the building. The sensor
should never be in direct sunlight.
• Be sure the location is away from doors, windows, exhaust fans, vents, or other
possible heat sources.
• The sensor should be mounted approximately 10' feet above ground level.
• Adhere the Outdoor Label provided to the back of the sensor base.
• Use the Enclosure Base bottom knockout for the conduit. Use the locknut to hold
the conduit and enclosure base together. Screw the cover to the base.
• If screws are used to affix the enclosure to the wall, make sure to seal around the
sensor and wall except from the bottom.
• The sensor wires can be extended up to 500' using shielded 2-conductor cable
(#18/2). Do not ground the shield at the sensor but at the control using the
terminal marked with an “O”.
• Do not run sensor wires in conduit with line voltage wiring.
ALERT
determining the proper location of the Outdoor Sensor is very important. The M4-CNC will base the
heat on the outdoor temperature information it receives from this location. if the sensor is in the sun, or
covered with ice, its reading will be different from the actual Outdoor temperature (Od).
System Sensor
In Well
Shield
Not connected
Well Locknut
Sensor
in Well
Well
Sensor 2-Conductor
Shielded Cable
System
Strap-On
Sensor
Shield
Not connected
Plastic
Tie-Wraps
Around Pipe
Outdoor
Sensor
snap-in
location
Shield
not connected
Conduit
Outdoor Label
on back of Sensor
Outdoor Sensor
Strap-On Sensor
Immersion Sensor
Mounting
screws
location
Seal around
sensor and wall
Outdoor
drip-hole
LAARS Heating Systems
HT# 059104-00 B