That is one sick picture
I have a lp heater and I am sure it is safe but I scares the hell outta me. I guess it is cause you can see it in action. The truth is even generating heat from the engine exhaust is still dangerous, we just kinda take it for granted it is all hidden and you really don't have a picture in your mind how it works.
Also there is a poop load of safety checks that monitor its progress to reach the heat levels, I know of three to keep my little legend in check. So that should say the manufacturers of these machines know how dangerous it is
there was a video on the net of hot water heater and what could happen if the safety checks failed... it took off like a ROCKET
This is no joke a carpet guy here in town was working down the street from me and asked to see if I could help him figure out what was wrong.
So I go down and his water cooled unit is blowing water out of the radiator... I touched the side of his van and it is HELLA HOT like HOT I look in and he has a little giant going to town in there with all the doors shut hoses all melted. I just looked at him and said DUDE you have to open your back door to get some air in here man your going to blow this thing up.
I quickly walked back and let him turn it of at the belly tank, that van was so stinking hot I can believe it didn't blow up!!
He is no longer around.