noun
vented heater; clean heater
A heater that vents combustion gases outside, keeping indoor air clean. Often used for gas or oil heaters with an exhaust pipe.
クリーンヒーターは排気を外に出すので、部屋の空気が汚れにくい。
A clean heater vents exhaust outside, so the room air stays cleaner.
Variant with a middle dot; less common in running text.
A fan heater that blows warm air; may or may not be vented. クリーンヒーター specifically refers to a vented type that exhausts fumes outside.
Wasei-eigo (Japanese-made English) from 'clean' + 'heater', referring to a heater that keeps indoor air clean by venting exhaust outside.