Wetbacks/ wet-backs and hot water tempering valves.

In New Zealand the term 'wet-back' or 'wetback' is used to mean a heat-exchanger fitted to the back of an open fire, wood burner or stove to provide hot water. These notes (a printed-out email) include information about the need for tempering valves with water which is heated in this way and then used in the home. The part of the NZ Building Code which requires this is referred to: http://www.dbh.govt.nz/building-code-compliance-documents#free-download The notes includes a link to the website: http://www.ecobob.co.nz/EcoArticle/1069/105/Water-Heating.aspx which says: "Wetbacks ... create very high water temperatures, high enough to boil water, with attendant risks to users. As with all hot-water systems, a tempering valve must be included in the system to meet regulations governing water temperature at the point of supply."