False Flame Lockout / Error 20; Low Water Pressure; Flame Loss - Keston HEAT 2 45 Installation & Servicing

5.5 FALSE FLAME LOCKOUT / ERROR 20

Reset the boiler, does boiler work OK?
no
Disconnect the electrical connection to the Flame
Sense Electrode. Is there continuity between the
Electrode and earth?

5.6 LOW WATER PRESSURE

Are the boiler and CH system filled with water and all
Isolation and Radiator Valves open?
yes
Does the wiring from the Water Pressure Switch to the
PCB have continuity and is it securely connected?

5.7 FLAME LOSS

If the boiler is Reset, does the boiler Ignite
for a short time and then Extinguish
no
Is the Gas Pressure available at the boiler > 18mBar?
yes
Is the following voltage available at the Gas Valve?
(approximately 215Vdc for 45 & 55kW)
yes
Check Spark Generator and associated Harness
for continuity, visual condition and position (Refer to
Section 3.18). Are these functioning correctly?
yes
Check Ignition Electrode and associated Harness
for continuity, visual condition and position (Refer to
Section 3.12). Are these functioning correctly?
yes
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
Installation & Servicing
SECTION 5 - FAULT FINDING
yes
no
Check the Detection Electrode and associated Harness
yes
for continuity, visual condition and position (Refer to
Section 3.13). Check if the Condensate Pipe is blocked.
Check if the Flue is blocked. Replace as necessary.
yes
Check routing and integrity of internal boiler
wiring is OK. Check condition of Flame
Sense Electrode and replace if deteriorated.
Replace Flame Detection Electrode
Check routing and integrity of internal boiler wiring
no
Fill and vent the system and open all
Isolation Valves
Ensure wiring has continuity and is
no
securely connected
yes
Replace Water Pressure Switch
no
Check Gas Supply and rectify fault
Check wiring from Gas Valve to PCB
no
and replace if necessary, otherwise
replace the main PCB
no
Replace Spark Generator and
Harness as necessary
no
Replace Ignition Electrode and
associated Harness as necessary
no
Replace Gas Valve
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