- Burners, furnaces, boilers, and strokers (2)
- Boilers, low-pressure heating: steam or hot water (3)
- Gas burners, industrial (2)
- Oil burners, domestic or industrial (3)
- Room and wall heaters, including radiators (1)
- Radiators, except electric (1)
- Solar heaters and collectors (4)
- Steam heating apparatus (1)
