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
