Baxi bahama honeywell pcb RL2 clicking

[uk_sojourn]

Yes the dreaded Bahama. this time we have:
The flame going out after 8 seconds then re-starting for 8 seconds.
metered both flow switches tested ok.
APS tested ok.
new flame sensor fitted. no difference
No inline filters found, (previously found in and out filters on different bahama and the one coming from the boiler was choked.)
Over temp. metered ok.
diverter valve sluggish but motor unit travels correctly. (ordered new!)
secondary heat exchanger flushed. (had noticed primary side to hot to hold but secondary tepid.)
the relay in the top right corner of the honeywell pcb clicks in time with the flame outs.

What controls that relay?

Suggestions please, and yes I am saving up for a replacement boiler.
unit was serviced a year ago.

 

[baxpoti]

The flame going out after 8 seconds then re-starting for 8 seconds.

On dhw or heating or both?

 

[uk_sojourn]

Hi Baxpoti,
Originally I was having problems with both but the flush sorted the Hot water.

Thanks

 

[baxpoti]

If dhw ok and c/h not then you need to check flame sensing probe is actually sensing a flame. (boiler fires on low flame for first 30 secs in c/h mode)

If no flame is detected replace flame sensing probe, or realign the electrode over the burner rail.

 

[uk_sojourn]

Hi, I fitted a new probe as covered above.

 

[Agile]

Fitting a new electrode is only part of the process of detecting the flame!

Because of the high impedances and voltages involved, the PCB incorporates several high value resistors which can fail causing a lack of flame detection.

Tony

 

[uk_sojourn]

I knew it was going to be expensive..

 

[baxpoti]

Hi, I fitted a new probe as covered above.

Sorry I missed that!

Is it in the flame?

Hot water definitely ok?

 

[uk_sojourn]

Yes its in the flame.
The hot is better now I have fitted the new diverter valve (plastic) original brass.
what i did notice was the water pump is hotter than the water pipes to it. Maybe there is a flow issue with the pump? I have checked the pump for air at the bleed valve.