Answer: boilers

AnswerCrossword Clue
BOILERS

Water heaters

BOILERS

Heat sources

BOILERS

They'll keep you warm in winter

BOILERS
Hot-water tanks
BOILERS
Water tanks.
BOILERSHeating plants.
BOILERSJanitor's concern.
BOILERSCertain containers.
BOILERSKettles.
BOILERSHeaters
BOILERSSteam generators
BOILERSSubmerged coral reefs
BOILERSCertain tanks
BOILERSProviders of housewarmings?
BOILERSFurnaces
BOILERSHeating equipment