Biasi Prisma 28se

[tazman]

This boiler has an intermittent fault whereby hot water demand causes it to light and increase temperature as you'd expect. Then it will either modulate the flame down and keep the burner alight, or it will reach temperature and then the burner will go out with no modulation down and relight again in a few seconds.
I do understand the nature of intermittent faults but hope that some of you experts may be able to enlighten me.

 

[twgas]

probably plate h/ex blocked due to cr*p in system

 

[tazman]

Hi Mick, Thanks for the superquick reply! As I recall it sometimes did this whilst the ch was on for a few minutes too. Would that suggest both h/e being blocked? I did put some Aqueous logic cleaner through the system last year and didn't really see much crud come out of the rads when I flushed it out.

 

[jamsco]

Check if theres a filter on the cold main into boiler, may be blocked? Otherwise possible blockage in dhw ht/ex or diverter. is diverter operating as it should? Good luck.

 

[jamsco]

Is C/H working ok? Does this D/H/W fault occure every time you draw H/W?

 

[tazman]

Hi and thanks Jamsco, No blockage on cold water in, and the divert valve is working fine. I'm just trying to pin down this intermittent fault as best as possible before committing to a course of action.

 

[tazman]

Will go and run the ch to see if the fault still occurs, and no the burner modulates perfectly on dhw demand.

 

[jamsco]

I had a similar fault on a ferroli a while back, C/H was fine but D/H/W cause boiler to light then go to lock out, checked filters etc. turned out to be partially blocked venturi in flue, worth checking? Good luck

 

[Agile]

I had a similar fault on a ferroli a while back, C/H was fine but D/H/W cause boiler to light then go to lock out, checked filters etc. turned out to be partially blocked venturi in flue, worth checking? Good luck

Part of the "Gas Train" and should normally only be worked on by a CORGI or a homeowner who is competent to work on gas!

Tony

 

[tazman]

Thank you Jamsco!!