Update on Hallowell Acadia heat pump: going into the 3rd heating season, the system is not working. I'm on emergency back up heat, and the people at Hallowell don't answer the phone when the tech from Enwise calls them for help. At this point I feel sorry for Enwise, they've lost money on this installation but in fairness to them they are still answering my calls. This whole thing has been a nightmare. So far I've not gone through a winter without having to have this unit fixed. The Rinnai tankless hot water heater is great.