All four models do have the same heating capacity 1,9 kWh (low) to 4,8 kWh (high). The fuel consumption is per 24hour: 4,8 ltr (low) and 12 ltr (high). Your choice of heater will be determined primarily by the space available and, of course, what appeals to you. These diesel heaters do fit well in vessels of 30 to 60 feet or for heating up cabins of 40 to 80 cbm.