I called mine the howler. It was a ching Chong brand, Royal something. 12kbtu capacity. I saved a few hundred dollars a couple of winters in a row using it to heat a two story saltbox I was renting. Main idea is just exhaust the processed air you don't want. Unless you have a tiny house or something airtight, the thing will do as well as it can.
Ecomodded started a thread on this a few years ago:
https://ecorenovator.org/forum/showthread.php?t=5430