Heaters

Heaters are a researchable building modifier that raise the heat level of non-residential buildings by 1 by consuming 1 coal every hour. Once researched, most non-residential buildings can have heaters toggled on or off as needed. Heaters can be further upgraded up to two times, with each tier increasing the heat level and coal consumption by 1.

Trivia

 * Heaters were known as "Boilers" in the Frostpunk demo.