Boiler water is chemically treated to maintain proper
operation of the boiler and therefore is not usable for domestic
hot water purposes. It can, however, be put to work heating
potable water. One of two methods is employed.
heat exchanger storage systems are equipped with a tank containing
the water to be heated for service use. The high temperature
boiler water (usually 180oF) circulates through a heat exchanger
located in the storage tank where heat from the boiler water
is transferred to the stored water. A higher capacity version,
called a pumped external heat exchanger, employs a pump to
achieve greater heat transfer in a smaller heat exchanger.
alternative method is the tankless coil water heater system.
A hot water coil is immersed in the hot water heating boiler.
There is no external storage and the boiler operates each
time there is a demand for hot water. Water flows through
the coil and is heated continuously.
the boiler provides a year round use, such as sterilization
in a hospital, either method can be inefficient during the
cooling season when a boiler, sized for a combined heating
and water heating load, is used for water heating only. Seasonal
efficiencies as low as 30% are possible. Tankless coil water
heaters can be made more efficient by the use of a shell-and-tube
type heat exchanger because the heat of the high-temperature
water in the shell reduces the need to fire the boiler for
every hot water demand.
Boilers can operate on natural gas, various types
of fuel oil (#2, #4, #5 and #6), coal, wood and electricity.
more information about Boilers, visit the Boilers module of
the Industrial Advisor.