I have an LG minisplit ductless system installed in my new third floor addition here in Toronto (outdoor unit model LMO240H; indoor units LMI090HP). The contractor who installed it said it should operate up to about -15C outside temp. We're currently at about -5C, and I'm not getting a lot of heat out of either head-unit (there are two). Should I be? What the the typical operating ranges for this (or similar) ductless heatpumps??