A dirty water heat exchanger keeps solids from settling out while passing through the heat exchanger and includes a cylindrical furnace duct, connected at a first end to a conventional burner, having a spiral liquid heating duct along which the dirty water passes from its first end to its second end. For More details visit: http://www.freepatentsonline.com/4632180.html

The unit is made of all copper with brazed connections. The heat transfer fluid connections are 3/4 inch and the hot water connections are 3/4 inch for universal fit. This unit can be used in solar thermal systems with approximately 64 square feet of collector surface area. For more details visit: http://kingsolar.com/catalog/mfg/21stcent/3ftquadrod.html

This indirectly heated potable water tank makes available an appliance meeting all the requirements for safe potable water and gives the consumer a device with a high continuous output of hot water, even when demand is high. For more details visit: http://www.freepatentsonline.com/4632180.html