Hot water tank Heat Extractors Home › Forums › Archives › Old Bulletin Board Archives › Hot water tank Heat Extractors This topic has 0 replies, 1 voice, and was last updated 25 years, 1 month ago by John Son. Viewing 0 reply threads Author Posts 15 Feb 1999 at 8:12 am #280441 John Son Would like info on how a Heat Extractor works on an electric hot water tank and what maintenance is required. Thanks for your help. Author Posts Viewing 0 reply threads The forum ‘Old Bulletin Board Archives’ is closed to new topics and replies.