PCM heat storage experiences for recreational vehicles? 100+kg of paraffin

[Hulmis Hulmu]

Greetings from Finland (Nordic Europe), its the best season for getting candle wax for free here - its so freezing they dont burn fully when in outside use, each church / graveyard / independence day (6h December) /monument candle leaves behind a cylinder shaped wax pipe. So we have quite big recycling project going on around that, and we are looking for any references and experiences about PCM (phase change material) in RVs. Any, really, car or a boat. :) We are speculating most people who live in the tin can of their choice, arent sub arctic, and that might be why we arent seeing that many paraffin experiences in this context.