Sunster 8 kW Toolbox Diesel Heater, Dual Power, App

The Sunster 8KW Toolbox Diesel Heater is number eight in our guide to diesel heaters. It costs £105.99 and carries 3.9 out of 5 from 105 ratings. It is the all-in-one shape: a sealed metal toolbox case with the fuel tank built in, a metal buckle lid and a sealed upper cover, and a dual input that takes either 12/24V DC or 110-240V AC and switches between them automatically, so it can run from a vehicle or from a mains socket. Sunster claims a 38% gain in combustion efficiency from a reinforced aluminium heat exchanger, full heat output up to 5,500 metres, and 3-5 minutes to feel the heat.

The 3.9-star average is doing a lot of hiding. The star breakdown on the page adds up to 100 rather than the 105 ratings quoted above it, and inside those 100, 64 are five-star against 19 one-star — more one-star ratings than four-star (9). The efficiency figure is the other number worth pausing on: this listing claims 38%, while Sunster's other 8 kW listing credits the same reinforced aluminium heat exchanger with 28%. One reviewer reports running the unit from a 300W power station at 123 watts of draw, on a heater sold as 8 kW. Everything below is taken from the Amazon listing and the ratings on it, not from testing by us.