National Oilheat Research Alliance 7
Heat Emitters/Terminal Units – Steam
systems can have many types of radiation to
provide heat throughout a structure, including
baseboard, convectors, radiators….
Heat emitters receive heat from the steam
circulating through the piping and deliver it to
the areas where they are installed.
It is always good practice to check the manufacturers
rating chart for the square foot of
steam that is required for each heat emitter.
Types of Heat Emitters
(aka terminal units)
Typical stream heating systems deliver
heat by convection. They circulate steam
through heat emitters, warming the air
around them. As the air is heated, it expands,
becomes less dense and rises. As the
warm air rises, the colder air it displaces
falls, creating heat convection currents.
These convective currents don’t require a
mechanical means to move the air.
Baseboard Heating
Finned-tube baseboard and cast-iron baseboards
use convection to circulate heat. Cooler
air at the floor level enters the bottom of the
baseboard and because of the heated material
in the baseboards, heat is transferred to the air
which then moves up the wall.
Baseboard location is usually along outside
walls to help these convective currents and to
remove the feeling of a cold wall or window.
Steam finned- tube baseboard features steel
tubing with fins attached. Manufacturers have
different types, sizes and numbers of fins per
inch.
Finned-tube baseboard
heats up rapidly and dissipates
its heat quickly.
Surface temperatures of
the units are not an issue
as they are protected
with covers. This system
works well when there is
enough clearance to create
convective currents. Cool
air enters the bottom and
Figure 4
Figure 5