Watts tekmar 294 - Universal Sensor Wiring and Mounting; EMS Connection Wiring; Universal Sensor Mounting

8
IOM-T-294 2205 © 2022 tekmar
+
-
EMS
+
Outdoor
Sensor
-
5
4
EMS Connection (Terminals 4, 5)
An Energy Management System (EMS) can be connected to the 294 to provide a target water
temperature. This signal replaces the outdoor air temperature sensor. Either a 0 to 10 V (dc) or
2 to 10 V (dc) signal may be used.
• Connect one wire from the EMS to the Outdoor (+) terminal 4.
• Connect a second wire from the EMS to the Outdoor (-) terminal 5.
A 0 - 20 mA signal can be converted to a 0 - 10 V (dc) signal by installing a 500 Ω resistor in
parallel between the Outdoor (+) and (-) terminals (4 and 5). The EMS Signal setting must be
set to 0-10.
A 4 - 20 mA signal can be converted to a 2 - 10 V (dc) signal by installing a 500 Ω resistor
in parallel between the Com (-) and EMS (+) In terminals (19 and 16). The EMS Signal setting
must be set to 2-10.
Mounting the Universal Sensors
These sensors are designed to mount on a pipe or in a
temperature immersion well.
The Universal Sensor should be placed downstream of a pump
or after an elbow or similar fitting. This is especially important if
large diameter pipes are used as the thermal stratification within
the pipe can result in erroneous sensor readings. Proper sensor
location requires that the fluid is thoroughly mixed within the
pipe before it reaches the sensor.
Strapped to Pipe
The Universal Sensor can be strapped directly to the pipe
using the cable tie provided. Insulation should be placed
around the sensor to reduce the effect of air currents on the
sensor measurement.
Immersion Well
If a Universal Sensor is mounted onto 1" diameter L type cop-
per pipe, there is approximately an 8 second delay between a
sudden change in water temperature and the time the sensor
measures the temperature change. This delay increases con-
siderably when mild steel (black iron) pipe is used. In general,
it is recommended that a temperature well be used for steel
pipe of diameter greater than 1
1
⁄4". Temperature wells are also
recommended when large diameter pipes are used and fluid
stratification is present. If the well is not a snug fit on the sen-
sor tube, use the heat transfer paste. Apply paste to the sides
of the sensor and place a pea-sized globule on the sensor tip.
Push the sensor into the well and when it bottoms out, press
firmly. The paste will be forced up the sides of the well.
Conduit Connection
The Universal Sensor and Universal Sensor Enclosure 080
(sold separately) are specifically designed to mount onto a
3
⁄8" ID temperature well that is supplied with an end groove.
To install the well, plumb a ‘tee’ into the pipe and fix the well
into the ‘tee’. The 080 enclosure has a
7
⁄8" back knockout that
must be removed and fitted over the temperature well. The
Universal Sensor is then inserted into the well and the retaining
clip supplied with the enclosure is snapped onto the well end
groove. If the well has a threaded end, the installer must sup-
ply a standard threaded conduit retaining ring. The two wires
from the sensor are connected to the terminal block provided
in the enclosure. The other side of the terminal block is used to
connect wires from the control.
Bottom of
Enclosure 080
Universal
Sensor
Cable Tie
Sensor
Well
Retaining
Clip
Universal
Sensor