I have a Worcester 19/24 CBi boiler (4 years old) which keeps locking out whenever I put the central heating on. The hot water is unaffected and it will run perfectly until I put on the central heating. Boiler fires up and runs for a few minutes then goes to lock out. I re-set it and go through the same cycle over & over. It may or may not eventually stay on but I have the same problem the next time I put on heating. One plumber suggested pump & flush the radiators! at the cost of £1,000 (no guarantee of success). Different plumber said I needed a new pump which he then fitted but that didn't make any difference. boiler still constantly locking out. Can anyone help please.

Adrienne, November 2009

pile of junk !!!!!!!!!!!!!!!!!!!

gerry, April 2010

I HAVE THE SAME BOILER, AT THE MOMENT THE BURNER COMES ON AND AFTER ABOUT TWO SECONDS GOES OUT AGAIN, CAN SOMEBODY TELL ME WHAT THE PROBLEM IS,

JOHN, December 2009

these boilers are prone to lock out first the flame sensing probes should be checked and cleaned then the leads of these probes should be inspected. if the probes and leads are ok look at the circuit board as you look at it on the right hand side towards the back they have scorch marks on where the gas valve joins the circuit board if you have black on the pcb then you will need a new pcb and gas valve also the boiler stat and over heat stat play up on these boilers are your rads hotter than normal ?
also in the fan unit you have a venturi if this is blocked then the boiler will lock out so this will need to be removed and cleaned out.

start with the spark electrodes and leads
then the venturi then the stats then pcb and gas valve

optigas, November 2009