Vokera linea 24 service

[Inverness]

Can someone explain what this is for in these boilers Minimum Adjustment Potentiometer ?
I'm servicing one tomorrow. I'll clean it out check all seals,tightness and letby test, burner operating pressure at max with hot water no more than 10 mb on max and then c h on min 1.9 mb I think. There's a combustion button that you press for maxim rate then you can take a gas rate. More advice would be greatly appreciated. Theses boilers and kinda new to me. I've read the manual so I don't look like an idiot when the customer is watching me complete this job.

 

[sammathias]

I would take burner out and clean it. Clean probs and also check expansion vessel pressure whilst boiler is drained.