This is an interesting project that was done by a YouTuber (Jasonoid (https://www.youtube.com/@Jasonoid)). He bought an inexpensive ($110) diesel heater that would normally be used in an RV/motorhome and set it up so that he can move it around easily and use it for portable heat. It cranks out up to 27,000BTU and looks like it will run continuously for about 7-8 hrs on a single tank of fuel while on high. He didn't give the specs on how much power it draws (hopefully he'll do some more videos in the future), but it runs on 12v and some of the users report it draws 100w at startup (a glow plug is used to start the burner) and then settles down to around 10w while running (fuel pump and fan).
Those diesel heaters really hadn't been on my radar, but it's an interesting idea. His whole setup (other than the battery) looks like it was well under $200. I really hadn't realized they start that cheap (yes, I recognize that this isn't exactly a high-end unit). Build a little window insert (like what you might use with a window A/C unit) with intake and exhaust ports on it in advance, and you'd be all set to provide some heat to your house during a power outage / furnace problem. Just use flexible pipe to hook up the exhaust and intake. I like his idea of using a 90-degree elbow to reorient the exhaust pipe so that it essentially becomes a quick connect/disconnect for setup/takedown.
This is a very interesting post. I've been watching a lot of videos on a similar unit like this. That will even run on cooking oil iirc. It's a German design that expired and is being copied in Chinese factories. It was originally designed to save fuel and be inexpensive. You know back before massive Corps bought up all the public utilities and started raping us? ;)
I'll try to post a couple newer videos. I don't recall seeing a price break down between one of these units. And more conventional heating methods. But seems much cheaper. And certainly a cheap entry cost.