with hot air led through heat-exchange ducts in the walls, floor, or ceiling

Full Title

Hot-air central heating systems; Exhaust-gas central heating systems > operating without discharge of hot air into the space or area to be heated > with hot air led through heat-exchange ducts in the walls, floor, or ceiling

Classification Context

Section:

MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING

Class:

HEATING; RANGES; VENTILATING

Subclass:

DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR