fault finding( A logical step wise approach?)

[eddiescully]

I was just reading the fault finding flow chart for a baxi solo 2 50pf and as i understand when fault finding boilers a logical step wise approach is required to quickly track down, isolate and repair faults and that you have to understand the concept and principles of the boiler conponents and how they work in relation to eachother and not just learning thr details of one particular model and expecting all others to be just like it but as i was just saying the baxi solo flow chart says- does fan run (no) - is lockout light on (no) - is "fan on" light on (no) - check control knob is turned on - check that the wires are connected to the thermostat sensor - check that the fan and APS plugs is connected - check continuity across sensor (1 M OHM at 20 degrees) - no continuity change sensor - check continuity across pilot solenoid (1.5 K OHM) - no continuity change pilot solenoid - check potentiometer. I cant understand if a logical step wise approach is applyed to fault finding why the hell would i be checking for continuity across the pilot solenoid when the problem is that the fan is not running, i am not that far into the ignition sequence to be checking the pilot solenoid???? Please explain

 

[Dan Robinson]

Try asking in the combustion chamber.

 

[nickso]

The first step in logical fault finding is usually to ignore the manufacturers instructions completely. The only thing they contain that is of any use is the rare inclusion of voltage and resistance readings.

 

[Boilerman2]

After getting caught on a Baxi Solo fan problem myself and needlesly changing a PCB I can confirm that the resistance of the pilot solenoid is critical, as if not correct the fan will not run!!

 

[eddiescully]

But why would a faulty pilot solenoid effect the fan from working? If you did not have the fault finding flow chart for the boiler you would never think of checking the resistance of the pilot solenoid because the fan is not working would you. I cant see a logical step wise approach being implemented to find that fault???

 

[FiremanT]

Because the pcb does a precheck of components. If it find something it isn't expecting ti will go no further. Which is why you can't temporarily bridge out or disconnect resistors or sensors etc.

 

[andytw]

The person to ask is either the person who wrote the flow chart or the person that wrote the code on the control board.

Consider this :-

Car engine does not turn over
Turn headlights on
Lights lit ?
No
Fit charged battery

One could ask what is the relevance of the headlights to the engine, but in this case we know the answer so it seems sensible.

In the case of the Baxi we do not know the answer so the step does not appear sensible.

andytw

 

[Boilerman2]

At the end of the day it all gets easier with experience!! I got caught by the Solo solenoid resistance after 34 years of Service Experience!

 

[Agile]

Eddie, how can it be logical to write ten lines without any paragraphs or sentences?