I have visible smoke coming from flue when the boiler starts up. What does this mean! The Boiler and Burner were installed only last Sept. I am not able to contact the installer at present. The boiler is a Grant 50/90 boiler-house model. I would really appreciate some advice

John, January 2013

when you say smoke, is it white or black?
if its white, this is correct and is condensing steam.
if its black, the combustion settings are way off and need a qualified oftec service engineer to set the burner up with a flue gas analser.
the air screw is on the right hand side of burner, a 3mm allen screw,
but if you twiddle this without the correct training and equipment you will risk melting the blast tube and rendering the boiler scrap.

mark, February 2013