> Gree has a system that claims to have full heat down to -31, so I'd say just keep researching and you'll probably be fine. Doing a quick search, they're usin

> Gree has a system that claims to have full heat down to -31, so I'd say just keep researching and you'll probably be fine. Doing a quick search, they're using 'standard' R410A refrigerant (PDF): * https://www.greecomfort.com/assets/our-products/multi-plus-ultra/documents/multi-plus-ultra-service-parts-catalog-d.pdf https://www.greecomfort.com/assets/our-products/multi-plus-u... the same as everyone else. It seems just that they though it worth the engineering effort to push a little further than most other companies. See anything with the label "For Extreme Conditions": * https://www.greecomfort.com/our-products/ https://www.greecomfort.com/our-products/