L A (Over Heat Sensor); L 8 (Fan); H 1 (Control Temperature Sensor) - IDEAL istor HE260 Installation And Servicing

99 L.......A......................... (OVER HEAT SENSOR)
Can the overheat condition be reset by pressing
the boiler reset button when the system is cold ?
Is the boiler and CH system filled with
water and all isolation valves open ?
Does the pump setting give a differential
across the boiler in excess of 25
Set CH control knob to maximum.
If the overheat trips again measure the flow temp:
o
Over 90 C Check control thermistor
o
Under 90 C Replace overheat 'stat
100 L....8..... (FAN)
Is nominal 330 V DC present across
red and blue at the fan connector as
reset button is pressed?
NO
101 H.....1..... (CONTROL TEMPERATURE SENSOR)
Remove the boiler control
thermistor from the CH
flow pipe and disconnect
thermistor wires.
Replace PCB
istor system store -
Installation and Servicing
FAULT FINDING
YES
YES
o
C
NO
(Refer to Frame 68) .
YES
Check wiring harness for
continuity. Is there continuity?
Check resistance. The sensors can be checked by
measuring their resistance, using a suitable multimeter
connected across the sensors' terminal pins
o
At 25 C expect
o
At 60 C expect
o
At 85 C expect
Are the thermistor values correct ?
YES
Is there continuity between the PCB
and the thermistor ?
NO
NO
Fill and vent the system and open all
YES
Check that the pump is rotating freely.
Replace the system pump
Note.
With V9 Primary Control PCB, overheat LA/HA or H9/L9 when
reset will display 3 horizontal lines and will not attempt to refire
until the temperature in the heat exchanger drops below 50
YES
Is 14V DC present
across yellow and pink
at the fan connector?
NO
YES
9,700-10,300 Ohms
2,400-2,600 Ohms
1,000-1,100 Ohms
YES
Replace overheat thermostat
isolation valves
Is differential now below 25
NO
Replace fan
Replace PCB
NO
Replace harness
NO
Replace the thermistor
NO
Check and replace wiring
as necessary
o
C ?
YES
OK
o
C.
67