It’s essentially a wish that the person may always have enough money for fuel, and enough fuel for a nice warm fire. It’s a wish for warmth. And a long life of comfort. A nice wish.
Fun side fact on reek! Edinburgh’s two personalities are generally differentiated by her two nicknames: ‘the Athens of the North’ and ‘Auld Reekie’. The Athens of the North refers to her status as a centre for learning and debate in the Enlightenment. Auld Reekie is Old Smokey – the dark, smokey, Jekyll-and-Hyde-in-dark-closes side of Edinburgh. The smokey city is something that we more associate with the more industrial places like Glasgow. But afore aw o them wis reekin, Embrae wis reekin. Auld Reekie, the original Big Smoke. Of course now it could be renamed Auld Reek Controlled Area. And probably a good thing too, sayeth Asthmatic McFarlane.