Hydronic Heating Boilers and Domestic Water Heaters Installation and Service Manual

OPERATION
Continued
Temperature Control Sensors
This is a two-stage temperature control that controls the burner
ignition, pump, and alarm functions. This temperature
controller can measure up to three different sensor inputs,
depending upon how the unit is set up. They are as follows:
1. Inlet Water Temperature Sensor
2. Multi-Purpose Temperature Sensor
3. Outside Air Temperature Sensor
Inlet Water Temperature Sensor
This sensor measures the inlet water temperature coming into
the unit.
Multi-Purpose Temperature Sensor
Depending upon how your unit is set up, this sensor can be
used as a system sensor or a tank sensor.
Outdoor Air Temperature Sensor
This sensor is only available on boiler units with an outdoor air
reset option. This allows you to tie boiler operation to the
outdoor air temperature. As outside temperatures drop, the
control will increase the temperature setting of the boiler. As
outdoor temperatures rise, the control will decrease the
temperature to the selected set point of the boiler. You can set
the control to shut the boiler off when a desired outdoor air
temperature level is reached.
Figure 37 - Outdoor Air Reset Chart Example
Boiler Application
Standard boiler units are shipped with two sensors; the inlet
water temperature sensor and the multi-purpose temperature
sensor. The multi-purpose sensor should be used as a system
sensor. Boilers with the outdoor air reset option also have an
outside air temperature sensor.
Water Heater Application
Water heater units are shipped with two sensors; the inlet water
temperature sensor and the multi-purpose temperature sensor
to be used as a tank sensor.
Placement of Sensors
Inlet Temperature Sensor
The inlet water temperature sensor is placed into the inlet
bulbwell on the boiler. This sensor is installed by the factory in
new units. Make sure to insert the sensor all the way into the
bulbwell, leaving no air pocket between the front surface of the
sensor and the back of the bulbwell. Air pockets are thermally
non-conductive and will cause sensors to not read accurately.
System Sensor
This is used for boiler applications. This sensor will control the
boiler operation based upon the water temperature within the
building loop.
Tank Sensor
This is used in water heating applications. Place the sensor in
the water storage tank to measure water temperature. For more
information on mounting the sensor, see Remote Mounting of
Sensors, page 33.
Outside Air Temperature Sensor
The outside air temperature sensor will only be used for boiler
systems. The outside air sensor is optional. You must purchase
the sensor from the appliance manufacturer. The sensor comes
with a housing that helps protect the sensor from the elements.
Mount the air sensor housing under the eve of the roof. Make
sure the housing is out of direct sunlight. This will ensure that
the sensor will accurately read the true outdoor temperature.
For more information on mounting the sensor, see Remote
Mounting of Sensors, page 33.
Hydronic Heating Boilers and
Domestic Water Heaters
32