Aftermarket installations – safety/liability

Hi all, I purchased a Campervan a couple of years ago and the previous owner had installed an aftermarket diesel heater inside which is connected up to the main fuel tank.

I haven’t done too much research into these but I knew from turning it on once or twice that I personally never felt comfortable with it from a safety perspective. It kicked out white smoke starting it up and the cheap one button display on it was difficult to use (particularly figuring out how to turn the thing off!).

I’m thinking of selling the van in the new year and I’m wondering what my best move is from a liability POV. Would it be easier to just remove this myself or sell with the specific declaration/agreement that using the heater would be at the new owners responsibility?