ECR International Utica Boilers MAH-125 Installation, Operation And Maintenance Manual page 114

L
Is main water filter and assembly
L
Is main water filter and clean and rotor free to move?
assembly clean and
NO
rotor free to move?
Clean or replace
NO
Clean or Replace
M
Temperature sensors faulty.
1.
Cold resistance approximately
1 0kO @ 77' F (CH sensor)
20kO @ 77' F (Flue sensor)
(resistance reduces with increase in temp.)
If pump is running the heat exchanger could be
2.
obstructed
N
Performs the autocalibration function (see the Service manual)
Display blank
0
Check obstruction in the flue duct
Performs the calibration function (see the Service manual)
p
Check the electrical connection
between Ru and pcb
FAULT SOLUTION SECTIONS
YES
PCB connector x22 Hall
effect sensor terminals.
Check the voltage is YES
YES
approximately 5 VDC
between the Red and
Blue wires. See Wiring
Diagrams.
NO
Replace PCB
YES
Verify the position of the Service key
YES
NO
PCB connector x22
Hall effect sensor terminals.
With water running
Check that the voltage is approximately
through DHW circuit,
YES
5 VDC between Red and Blue
measure red and white
See Wiring Diagram
wire for 2.8 VDC for
NO
flow triggering.
NO
Replace PCB
Replace Hall Effect Sensor
NO
f----i� �
I
Replace sensor
·1 � ---�
YES
�
I
Replace heat exchanger
·1 � -----�
Remove the obstruction on the flue pipe
44
Replace Hall Effect Sensor
Check DHW NTC YES
Replace PCB
senor for proper OHM
value
NO
Replace DHW NTC sensor
I
PN 240011430 REV. M [06/30/2019]