Below is a list of Water to Water Heat Exchangers manufacturers from St. Louis, Missouri. Water to water heat exchangers transfer heat energy from one liquid to another without bringing the two liquids into direct contact in a similar method as air to air heat exchangers. Typically with a shell and tube or spiral design, water to water heat exchangers work through forcing hot fluids to flow through heat-conducting tubes over which liquid coolants flow. The heat is absorbed by the coolants and thus removed from the water, dropping its core temperature and allowing it to move on in its process.