I have a 2.5 year old Worcester Bosch Greenstar Junior 24i boiler. When I turn on the hot water or central heating the boiler attempts to fire up and then switches off after 5-10 seconds and the reset and service light comes on. It then attempts to fire up again and again the reset & service light comes on. After the 4th or 5th attempt the flame will light up and stay on consistently finally giving me hot water!

I have had the boiler serviced and the engineer couldn't diagnose the fault but thought it may be the air pressure switch. Another engineer had a look at it but didn't know what the problem was either and said I should get the PCB and flow sensor changed. I'm a bit worried as nobody seems to know what the fault is and I don't want to end up forking out a huge amount of cash for parts I may not even need.

Could anyone advise on this please?

serenity5143, August 2009

Just seen this question, can say without dout that these boilers have this habit. Fan, air pressure switch[they do have them] and overheat stat most likley.
I have had many years with these boilers and they are at the very bottom of the worcester range. Say no more.

timtim, December 2009

Hi Ian, many thanks for your prompt response. The Npower engineer who did the 30 point boiler service checked the CO2 ratios and the gas inlet working pressure. All was fine. Not sure if the gas valve was checked as part of the service so I'll get it looked at.

serenity5143, August 2009

fist things first, i don't think this boiler even has an air pressure switch. first thing to have checked is the condition of the elecrodes and the combustion ratios. if the co2 ratio's aren't bang on then these boilers can struggle to light. next check would be the gas inlet working pressure. if all that's ok then i'd suspect that the gas valve is sticking, however it's hard to diagnose without seeing it.

Ian, August 2009