STEAM systems use the vapor phase of water to supply heat or?kinetic energy through a piping system. As a source of heat@ steam can heat a conditioned space with suitable terminal heat transfer equipment such as fan-coil units@ unit heaters@ radiators@ and convectors (finned tube or cast iron)@ or steam can heat through a heat exchanger that supplies hot water or some other heat transfer medium to the terminal units. In addition@ steam is commoniy used in heat exchangers (shell-and-tube@ plate@ or coil types) to heat domestic hot water and supply heat for industrial and commercial processes such as in laundries and kitchens. Steam is also used as a heat source for certain cooling processes such as single-stage and two-stage absorption refrigeration machines.
ASHRAE HVAC SYSTEMS AND EQUIPMENT IP CH 10-2008 history