INSTALLATION AND OPERATION INSTRUCTIONS
12
BT INDIRECT SERIES – WATER HEATERS
DANGER
DO NOT connect thermistor
sensors to “Therm” terminals
on the IBC control board.
An overheating hazard can
result, potentially causing
serious personal injury and/or
property damage.
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.
1.
Install electric wiring and grounding in accordance with the National Electrical
code and local regulations.
2.
All water heaters are supplied with an aquastat for connection to most
boilers. Follow the wiring instructions supplied with the aquastat and the
installation instructions for the boiler the water heater is being connected to.
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 makes, an aquastat thermostat is required.
4.
Reference should be made to the Installation Manual for the boiler as well.
4.1 Temperature Sensor
The Temperature Sensor supplied with the IBC 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 supplied sensors. Compatible water
temperature sensors are readily available from your IBC distributor.
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. The sensor leads
must be disconnected from the terminal strip while taking the reading. 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 to the actual
sensor temperature and the resistance value listed for that temperature in Table 4
(below). Do not apply voltage to the sensor (damage may result).
TEMPERATURE
RESISTANCE
TEMPERATURE
RESISTANCE
°F
°C
Ω
°F
°C
Ω
30
-1
34,558
115
46
4,184
35
2
29,996
120
49
3,760
40
4
26,099
125
52
3,383
45
7
22,763
130
54
3,050
50
10
19,900
135
57
2,754
55
13
17,436
140
60
2,490
60
16
15,311
145
63
2,255
65
18
13,474
150
66
2,045
70
21
11,883
155
68
1,857
75
24
10,501
160
71
1,689
80
27
9,299
165
74
1,538
85
29
8,250
170
77
1,403
90
32
7,334
175
79
1,281
95
35
6,532
180
82
1,172
100
38
5,828
185
85
1,073
105
41
5,210
190
88
983
110
43
4,665
195
91
903
Table 4: Temperature Sensor resistance values
WARNING
IBC water heaters are
supplied with a 10kΩ
thermistor sensor to be
inserted into the temperature
well of the tank, and secured
with a retainer clip or cap.
The thermistor must be solidy
affixed so as to prevent it
from falling out or 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.
ELECTRICAL
4.0
