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Domestic Hot Water - Follow operational sequence<br />
Turn selector to<br />
neon illuminated<br />
YES<br />
NO<br />
Go to section ‘A’<br />
Is mains water filter and differential<br />
assembly clean?<br />
YES<br />
Replace diaphragm<br />
YES<br />
DHW flow valve diaphragm<br />
damaged<br />
Turn thermostat to max.<br />
Open DHW tap fully. DHW<br />
flow switch operated<br />
NO<br />
YES<br />
DHW flow rate more than<br />
2.5l/min.<br />
NO<br />
DHW flow valve rod<br />
obstructed<br />
YES<br />
Primary water is diverted<br />
from CH system to DHW heat<br />
exchanger and flow microswitch<br />
operated<br />
neon illuminated<br />
NO<br />
Continuity across DHW flow<br />
microswitch terminals and<br />
PCB - A5 connector terminals<br />
5 & 6<br />
NO<br />
YES<br />
Replace DHW flow microswitch<br />
Replace PCB<br />
YES<br />
Pump runs<br />
YES<br />
NO<br />
neon flashing<br />
Go to section ‘B’<br />
Primary flow switch operated<br />
YES<br />
Fan runs at max speed<br />
YES<br />
NO<br />
NO<br />
neon flashing<br />
Go to section ‘C’<br />
neon flashing<br />
NO<br />
neons flashing<br />
YES<br />
Turn selector to reset position.<br />
If regular resetting is<br />
required or appliance still<br />
does not operate investigation<br />
is necessary<br />
Go to section ‘J’<br />
Go to section ‘D’<br />
Air pressure switch proved<br />
NO<br />
neon flashing<br />
Go to section ‘E’<br />
YES<br />
Spark at ignition electrodes<br />
for up to 10 seconds<br />
YES<br />
NO<br />
NO<br />
Replace PCB<br />
neon flashing<br />
NO<br />
YES<br />
Turn the selector to the reset<br />
position. If the light does not<br />
extinguish go to section H &<br />
K<br />
neon illumina-<br />
Burner on<br />
ted<br />
Go to section ‘F’<br />
YES<br />
Burner extinguishes<br />
after 10 seconds<br />
NO<br />
YES<br />
neon flashing<br />
Go to section ‘I’<br />
Burner output modulates to<br />
maintain temperature set at<br />
thermostat<br />
YES<br />
Close DHW tap<br />
YES<br />
DHW flow valve senses no<br />
flow.<br />
Primary water diverted to CH<br />
system. DHW flow switch<br />
released off<br />
YES<br />
Burner goes out<br />
NO<br />
NO<br />
Reduce the DHW flow rate.<br />
If burner does not modulate<br />
clean DHW temperature<br />
sensor and DHW heat<br />
exchanger. If modulation<br />
does not occur go to section<br />
‘G’<br />
Diverter valve spindle assembly<br />
faulty<br />
NO YES YES<br />
Fan stops<br />
Pump stops<br />
36<br />
Operation sequence correct
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