As concrete producers in colder climates renovate their ready-mix plants, they are finding that direct-contact water heaters provide ample hot water on demand — at lower cost than traditional direct-fired hot water tanks or boilers. Hot water is required to ensure consistency of the concrete mix during cold weather.
Direct-contact water heaters work differently from direct-fired water tanks with firetubes, and from boilers. Typically, they are vertical cylinders with a section of diffusion material inside the top; a burner in the middle; and a collection area at the bottom. Water is sprayed into the top of the heater, and it migrates downward through a section of diffusion material called packing. Packing typically is made from stainless steel formed into rings of various shapes and sizes. These rings provide the surface area where heat is transferred to the water from burner gases.