Keston C36 Combi

[tschodt]

This is more of a tip.

Had some trouble with this one 6 months ago, troubleshooting suggested faulty ignition PCB.
Managed to source a new one online for just over £100 (plus VAT).
Right enough, after replacing the PCB, the boiler worked fine.

Recently DHW stopped working.
Strangely troubleshooting resolved issue with no remedial action...
Step 1 - check DHW thermistor.
Installer display #4 dips when DHW demand is present (expected).
Step 2 - check DHW flow sensor.
Installer display #8 becomes non-zero when DHW demand is present (as it should) and now the boiler delivers DHW...
It seems boiler was ignoring the DHW flow sensor until the flow sensor reading was queried, after which boiler behaves normally...
Cannot claim to understand why.

 

[Agile]

Did you open the boiler and measure resistances?

Tony

 

[Dan Robinson]

Its a Keston - be grateful it didn't implode at the merest thought of having to do something remotely to do with burning gas.