On Sat, 7 Jul 2018 at 19:48, Norbert Senf <norbert.senf at gmail.com> wrote: > Domestic boilers are regulated in terms of pounds of PM emissions per million BTU's of delivered heat. The limit is 0.32 lb/MMBtu. At 75% efficiency, this is equivalent of 1.7 g/kg. Norbert is that emission limit applicable to any boiler fired by gas oil or coal? Andrew