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O
T
The
MNI
HERM
Condition
Stack
Sensor
Flow Switch
Information
Stack sensor disconnected
•
•
Stack sensor wiring bad
Thermistor elements bad
•
Lockout: Stack Sensor Drift
Lockout: Stack Sensor Probe
•
Auto reset condition
Annunciation – "Flow switch error"
•
on Message Screen
Corrective Action
Check the sensor and wiring.
•
Repair or replace as needed.
The stack probe is a dual
•
element probe with 100K
thermistors. Measure the
resistance of each element
of the sensor and compare
to the resistance table below.
Replace if necessary.
Temp
Temp
Resistance
(°F)
(°C)
32
0
50
10
68
20
77
25
86
30
104
40
122
50
140
60
158
70
176
80
194
90
212
100
248
120
284
140
320
160
356
180
392
200
428
220
464
240
500
260
536
280
•
Verify the system is full of water
and all air has been purged from
the system.
•
Verify the boiler/heater is piped
properly into the heating system.
Check to see if the pump is on
•
and rotating in the proper
direction.
Confirm all ball valves are open
•
Check wiring to the flow switch
•
Check flow switch operation to
•
confirm paddle movement and
switch operation.
Page 115
(Ω)
334000
201660
125500
100000
80220
52590
35270
24160
16870
12000
8674
6369
3581
2117
1307
839
558
382
269
194
143
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