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4.0 Electrical
Danger
Do not connect thermistor sensors to “Therm” terminals on the IBC control board. It could result in
overheating, potentially causing serious personal injury and/or property damage.
1. Install electric wiring and grounding according to the National Electrical code and local regulations.
2. Water heaters are not supplied with an aquastat. For field-supplied aquastats, follow the wiring
instructions supplied with the aquastat and the installation instructions of the boiler being connected
to the water heater.
3. All water heaters are supplied with a 10KΩ temperature sensor that connects to the IBC control board
“DWH Sensor” terminals with standard 2-wire, 18 gauge thermostat wire. For other boiler models, an
aquastat thermostat is required.
4. In addition, refer to the Installation manual of the boiler.
4.1 Temperature sensor
The temperature sensor supplied with the IBC indirect water heater is an NTC Thermistor type with a
resistance of 10,000 ohms at 25°C and β = 3892. IBC does not recommend using 3rd party sensors. IBC
distributors can supply compatible water temperature sensors.
The resistance of the temperature sensor varies inversely with temperature. To test, measure the temperature
of the sensed environment and compare with the value derived from the measurement of the resistance
(obtained by connecting a good quality test meter capable of measuring up to 5,000 kΩ (5,000,000Ω) at the
controller end of the sensor lead).
To obtain a resistance reading, remove power to the boiler. When taking the reading, you must disconnect
the sensor leads from the terminal strip. Do not grip the sensor leads in your hands or place them on or
against a conductive surface or the reading will be compromised. Place multi-meter probes onto the bare
wire ends of the leads and obtain the reading. Compare the reading with the actual sensor temperature and
the resistance value listed for that temperature in the table below. Do not apply voltage to the sensor
(damage may result).
Warning
The Thermistor temperature sensor supplied with the IBC water heater is may not to be
compatible with other makes of boiler or controls, and its use may create a hazardous condition.
Do not use the IBC sensor with other appliance makes.
IBC indirect water heaters are supplied
with a 10kΩ thermistor sensor for inserting into the temperature well of the tank, and securing with
a retainer clip or cap. You must solidly affix the thermistor to prevent it from falling out or from
being pulled out. If the sensor is pulled out of the well, a continuous call for hot water will be
generated, resulting in elevated tank temperatures and risk of scalding.
Summary of Contents for IWT 119
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