Using water as the heat transfer medium is recognized as hydronics. The heated drinking water can also supply an auxiliary heat exchanger to provide hot drinking water for bathing and washing. Air[edit] The federal government energy score Web-site has a lot more information regarding the star ranking system and the https://docs.google.com/spreadsheets/d/1wg_-AsMvSc3qrs7UTTRhj29jEk9maNNFTDlMhRKxfnM