| 1/00 | Steam central heating systems (F24D 10/00, F24D 11/00 take precedence) |
| 1/02 | Steam central heating systems (F24D 10/00, F24D 11/00 take precedence) operating with live steam |
| 1/04 | Steam central heating systems (F24D 10/00, F24D 11/00 take precedence) operating with exhaust steam |
| 1/06 | Steam central heating systems (F24D 10/00, F24D 11/00 take precedence) operating with superheated steam |
| 1/08 | Steam central heating systems (F24D 10/00, F24D 11/00 take precedence) Feed-line arrangements, e.g. providing for one-pipe system |
| 3/00 | Hot-water central heating systems (F24D 10/00, F24D 11/00 take precedence) |
| 3/02 | Hot-water central heating systems (F24D 10/00, F24D 11/00 take precedence) with forced circulation, e.g. by pumps |
| 3/04 | Hot-water central heating systems (F24D 10/00, F24D 11/00 take precedence) with the water under high pressure |
| 3/06 | Hot-water central heating systems (F24D 10/00, F24D 11/00 take precedence) with the water under high pressure Arrangements or devices for maintaining high pressure |
| 3/08 | Hot-water central heating systems (F24D 10/00, F24D 11/00 take precedence) in combination with systems for domestic hot-water supply |
| 3/10 | Hot-water central heating systems (F24D 10/00, F24D 11/00 take precedence) Feed-line arrangements, e.g. providing for heat-accumulator tanks, expansion tanks |
| 3/12 | Hot-water central heating systems (F24D 10/00, F24D 11/00 take precedence) Tube and panel arrangements for ceiling, wall, or underfloor heating (electric underfloor heating F24D 13/02; special adaptations of floors for incorporating ducts, e.g. for heating or ventilating, E04B 5/48; building elements of block or other shape for the construction of parts of buildings characterised by special adaptations, e.g. serving for locating conduits, E04C 1/39; building elements of relatively thin form for the construction of parts of buildings with special adaptations for auxiliary purposes, e.g. serving for locating conduits, E04C 2/52) |
| 3/14 | Hot-water central heating systems (F24D 10/00, F24D 11/00 take precedence) Tube and panel arrangements for ceiling, wall, or underfloor heating (electric underfloor heating F24D 13/02; special adaptations of floors for incorporating ducts, e.g. for heating or ventilating, E04B 5/48; building elements of block or other shape for the construction of parts of buildings characterised by special adaptations, e.g. serving for locating conduits, E04C 1/39; building elements of relatively thin form for the construction of parts of buildings with special adaptations for auxiliary purposes, e.g. serving for locating conduits, E04C 2/52) incorporated in a ceiling, wall or floor |
| 3/16 | Hot-water central heating systems (F24D 10/00, F24D 11/00 take precedence) Tube and panel arrangements for ceiling, wall, or underfloor heating (electric underfloor heating F24D 13/02; special adaptations of floors for incorporating ducts, e.g. for heating or ventilating, E04B 5/48; building elements of block or other shape for the construction of parts of buildings characterised by special adaptations, e.g. serving for locating conduits, E04C 1/39; building elements of relatively thin form for the construction of parts of buildings with special adaptations for auxiliary purposes, e.g. serving for locating conduits, E04C 2/52) mounted on, or adjacent to, a ceiling, wall or floor |
| 3/18 | Hot-water central heating systems (F24D 10/00, F24D 11/00 take precedence) using heat pumps |
| 5/00 | Hot-air central heating systems (F24D 10/00, F24D 11/00 take precedence; air conditioning F24F); Exhaust-gas central heating systems |
| 5/02 | Hot-air central heating systems (F24D 10/00, F24D 11/00 take precedence; air conditioning F24F); Exhaust-gas central heating systems operating with discharge of hot air into the space or area to be heated |
| 5/04 | Hot-air central heating systems (F24D 10/00, F24D 11/00 take precedence; air conditioning F24F); Exhaust-gas central heating systems operating with discharge of hot air into the space or area to be heated with return of the air to the air heater |
| 5/06 | Hot-air central heating systems (F24D 10/00, F24D 11/00 take precedence; air conditioning F24F); Exhaust-gas central heating systems operating without discharge of hot air into the space or area to be heated |
| 5/08 | Hot-air central heating systems (F24D 10/00, F24D 11/00 take precedence; air conditioning F24F); Exhaust-gas central heating systems operating without discharge of hot air into the space or area to be heated with hot air led through radiators |