Page 18 – Bulletin 100-50-9.1
5.4.4 DEFROST TERMINATION
TEMPERATURE
5.4.4.1 MOUNTING
The defrost termination temperature sensor is required
for defrost control. The sensor must be mounted to the
coldest part of the evaporator coil. Typical location is on
the last return bend of the coil circuit, as shown in Section
5.4. Note: Some coil manufacturers have designs
that allow the sensor to be placed inside of the coil;
consult the manufacturer for proper location. Ensure
that the sensor is located at least 10 inches away from hot
gas lines or heaters. Secure with two heavy duty zip ties.
Note: For medium temperature cases, the controller
may be set-up to terminate using the discharge or
return air temperature sensor.
5.4.4.2 WIRING
With controller unpowered, carefully route the orange
Defrost Termination sensor leads to the controller. Take
caution to route the leads away from sharp edges, fans and
defrost heaters. Ensure the terminal screws on the controller
are backed all the way out. Insert the leads of the sensor
wire into “Def Term” location on the controller. Tighten
the terminal screws to 3-5 in.-lb. Carefully tug the leads
to ensure they are secure. See the following figure. Note:
Leads are not polarized and may be installed in either
location. One lead of the Defrost Termination sensor
will share the terminal with the Return Air sensor.
5.4.2.1 WIRING
With controller unpowered, carefully route the green
Discharge Air sensor leads to the controller. Take caution
to route the leads away from sharp edges, fans and defrost
heaters. Ensure the terminal screws on the controller
are backed all the way out. Insert the leads of the sensor
wire into “Dsch Air” location on the controller. Tighten
the terminal screws to 3-5 in.-lb. Carefully tug the leads
to ensure they are secure. See the following figure. Note:
Leads are not polarized and may be installed in either
location. One lead of the Discharge Air sensor will
share the terminal with the Coil Out sensor.
5.4.3 RETURN AIR TEMPERATURE
5.4.3.1 MOUNTING
The return air temperature sensor is optional and is not
required for case temperature control. The sensor must
be mounted inside of the refrigerated display case. Typical
location is in the return air grille of the case. Ensure that the
sensor is greater than 4 inches away from the evaporator
coil surface. Secure with two heavy duty zip ties. Note: The
controller may be configured to use the discharge
air sensor or return air sensor as the control point.
If return air is the control point, then the return air
sensor is required for operation.
5.4.3.2 WIRING
With controller unpowered, carefully route the green Return
Air sensor leads to the controller. Take caution to route the
leads away from sharp edges, fans and defrost heaters.
Ensure the terminal screws on the controller are backed all
the way out. Insert the leads of the sensor wire into “Rtn Air”
location on the controller. Tighten the terminal screws to
3-5 in.-lb. Carefully tug the leads to ensure they are secure.
See the following figure. Note: Leads are not polarized
and may be installed in either location. One lead of
the Return Air sensor will share the terminal with the
Defrost Termination sensor.
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