I bloody love my diesel heater, one of the best things I have bought for the garage. I put it on a half hr before I need to go out there, it’s a big and mostly uninsulated double garage and it takes the edge off the cold pretty fast. I did open it up and changed the fuel lines after a year or so as the ones on it were shit. It runs most of the day on 1-2 litres of diesel.
I have noticed that the exhaust gas is very hot so I was half heartedly looking for one of those tall radiators on marketplace, and was going to run the exhaust through that to recover a bit more of the heat. Not done it yet tho.