52
EVOMAX
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Installation & Servicing
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74 oVERHEAt LoCkout
Has PCB just been replaced?
Reset Boiler
yes
no
Are the boiler and CH/DHW system
filled with water and are all isolation
valves and radiator valves open?
Fill and vent the system and open all
isolation valves, then reset the boiler.
no
yes
Is the flow/return differential across
the boiler in excess of 30ºC?
Check the flow and return
thermistors (refer to Frame 80 & 81)
no
yes
Check that the pump is rotating freely.
Is the differential now below 20ºC?.
Replace the pump, then reset the boiler
no
yes
Reset the boiler
75 IGnItIon LoCkout
If the boiler is reset, does it ignite for a
short time and then extinguish?
Check the detection electrode and associated harness
for continuity, visual condition and position (refer to
Frame 67). Check if the condensate pipe is blocked.
yes
no
Is the gas pressure available at the boiler > 18mbar?
Check gas supply and rectify fault
no
yes
Is the following voltage available at the Gas Valve?
(approximately 215Vdc for 30, 40, 60, 80 and 150kW)
(approximately 240Vac for 100 and 120kW)(* See note)
Check wiring from Gas Valve to PCB
and replace if necessary, otherwise
replace the main PCB
no
yes
Unplug the Gas Valve, is the resistance between the
outside pins between 1k
Ω
and 10k
Ω?
Replace Gas Valve
no
yes
Check Spark Generator and associated Harness for
continuity, visual condition and position (refer to Frame
58). Are these functioning correctly?
Replace Spark Generator and
Harness as necessary
no
yes
Replace Ignition Electrode and
associated Harness as necessary
no
Check Ignition Electrode and associated Harness for
continuity, visual condition and position (refer to Frame
66). Are these functioning correctly?
yes
Replace Gas Valve
no
Check Syphon and condensate drain pipework for blockage
and rectify if necessary. Boiler now working OK?
* Note: due to the wave form of the rectified voltage, the reading will vary depending on the type of meter used to measure the
value. In general terms a reading of greater than 150V indicates that the correct voltage is supplied to the gas valve.
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