From Longman Dictionary of Contemporary Englishsmoke like a chimneysmoke like a chimneyif someone smokes like a chimney, they smoke a lot of cigarettes or tobacco – used humorously → chimney
Examples from the Corpus
smoke like a chimney• She's only thirteen and she already smokes like a chimney.• The only sadness was that they all appeared to smoke like chimneys.• My granddad, who smoked like a chimney and lived to 97, was lucky enough never to encounter a promoter. 