These heaters are placed outside of the unit that is being heated while the ducting hose blows in the heat. Fitted with its own thermostat the required temperature can be easily controlled. 
This heater is widely recognised as being amongst the UK's most popular indirect oil-fired heaters for use in marquees, temporary structures, the construction industry, and the horticultural & agricultural sectors.
 
Small:
Output: 72,000 BTUs
Fuel Tank: 46L
Run Time: 18 hours
 
Large:
Output: 39kW (133,000 BTUs)
Fuel Tank: 65L
Run Time: 12 hours
Dimensions: L1310 x W490 x H1020
Noise Level @1m: 74dBA
Fuel consumption: 3.9kg/h
 
110V. Transformers available here.