Boiler only about 9 years old - for last 2 months has been locking out all the time, changed nozzle, been serviced, changed photocell (although doesn't seem to be anything wrong with it) finally found that burner is getting clogged up with sooty tar but why now??? Did have new oil delivery a few weeks before this started but isn't all oil meant to be same sourced as a commodity! now having to clean out the burner every week as it locks out again. any ideas out there why this has started happening gratefully received!

Richard Taylor, November 2010

thanks very much will check this all out.

Richard Taylor, November 2010

During the service was the CO ratio checked?
Is the air intake clear and set correctly?
Is the nozzle 'as specified'? (there are many types)

It's easy to assume 'oil is oil' but if you have sourced from a different supplier, or your supplier has sourced differently, who knows?
Get the burning ratio correct and the problem will cease.

Carefree, November 2010