the heated air comes out the top front
grates. Furniture placement in front and
proper space under the cabinet are critical
for the finned-tube baseboard to work
properly.
Cast iron baseboard heats up slowly
and cools off slowly. Surface temperatures
are high and there are no protective
enclosures. Cast iron baseboard also
provides radiant heating because the
large mass of iron stays hot even after
the burner shuts off, and slowly releases energy
into the space.
Radiators
Cast iron radiators deliver heat in a way that
is similar to cast iron baseboard; they heat up
slowly and cool off slowly, but surface temperatures
are high and there are no protective
enclosures.
Flat Panel Radiators
Flat panel radiators are a cross between finnedtube
baseboard and radiators. There is not as
much mass as a radiator and also fewer fins
on the back side. These are typically steel
and manufactured to a variety of lengths and
heights. The steel mass adds to the radiant
energy into the room and the fins help create
convective currents.
Fan Coils
Fan coils are small convectors with fins installed
in ductwork. The steam enters the fan
coils and air is circulated in the home by the
unit’s own fan blowing across the fins.
Steam Radiator Valves
(Supply valves)
With a one-pipe steam system, supply valves
are located at the heat emitter’s bottom connection.
8 National Oilheat Research Alliance
Figure 6
They control the admission of steam, and
out-flow of condensate.
In a one-pipe system, the supply valve
should always be fully open or tightly closed,
since a partially open valve obstructs the free
flow of steam in and condensate out. Figure 6.
With a two pipe system, supply valves are
located at the heat emitter’s top connection.
These valves can be throttled to regulate the
heating rate.
Steam Radiator Vents - The radiator
air vent or air valve (AKA steam vent or steam
valve) is found on the opposite side of the heat
emitter from the supply valve. The vent allows
air to pass out as steam enters the emitter,
closes against the passage of steam and opens
at the end of the heating cycle to allow air
back in.
Radiator vents are available in fixed and
adjustable types. A fixed vent releases air at a
fixed rate and a variable vent can be adjusted to
release air at different rates.
In general, small heat emitters use smaller
(slower) vents and large heat emitters use
larger (faster) vents.