For heat provision in inaccessible areas, satellite towns etc, where no mains supply has been established, or for industrial premises where no boiler room is required.
Standard boiler sizes (in kW): 400, 600, 800, 1000, 1500, 2000, 2500, 3000.
| kW | BTU/hour |
| 400 | 1,364,857 |
| 600 | 2,047,285 |
| 800 | 2,729,714 |
| 1000 | 3,412,142 |
| 1500 | 5,118,213 |
| 2000 | 6,824,284 |
| 2500 | 8,530,355 |
| 3000 | 10,236,426 |