| 236 / | HD | AUTOMATIC TEMPERATURE AND HUMIDITY REGULATION |
| 20 R | | CLOSED FLUID HEATERS {8} |
| 21 R | DF | .~> Safety cut-out {1} |
| 22 | DF | .~> Radiator type |
| * | DD | .~> Combined thermostat and flow controlled {2} |
| 24.5 | DF | .~> Flow and pressure controlled |
| 25 R | DF | .~> Flow controlled {1} |
| 26 R | DF | .~> Pressure-operated {11} |
| * | DD | .~> Thermostatic {2} |
| 20 A | DF | .~> Top burner control |