Condensate - the water formed when steam cools in a heat emitter or piping. The
capacity of traps, pumps, etc., is sometime expressed in lbs. of condensate they will
handle per hour. One pound of condensate is equal to approximately 4 sq. ft. of steam
heating surface (240 BTU per hour per sq. ft.)
Condensate Pump - a pump used to return condensate to the boiler where it cannot
be done by gravity.
Cooling Leg - a length of uninsulated pipe with sufficient cooling surface to
dissipate enough heat so that steam condenses so a trap can open to discharge
condensate from a heat emitter.
Counter-Flow System - a heating system in which steam and condensate flow
in opposite directions within the same piping. Piping should be one size larger than
in a parallel-flow system to allow sufficient space for free flow of both steam and
condensate.
Differential Pressure - is the difference in pressure measured between inlet and
outlet of trap or similar equipment.
Down Feed Riser - Piping that carries steam from supply main above to heat
emitters below. This piping also carries condensate from heat emitters to the return.
Down-Feed System – a heating system serving a multi-floor building in which
steam supply main is near the top of structure and down-feed risers carry steam to
heating units, as well as condensate to wet return. The condensate then flows to the
boiler via the Hartford Loop.
Drip Connection - This section of piping, at least 18" long, is the minimum
distance the end of the supply main must be above boiler water line for gravity flow
of condensate back to the boiler.
Where piping carries both stream and condensate, it is often desirable to drain off
condensate at various points to expedite steam flow. This condensate is drained off to
a return line by a connection called a “drip.”
Dry Return - the portion of the return piping located above the boiler water line.
Dry Saturated Steam - steam containing no water in suspension.
Equalizer - Piping from the end of the supply header that connects to the Hartford
Loop and then the bottom of the boiler to maintain pressure balance between the
boiler’s steam outlet and the condensate return inlet.
National Oilheat Research Alliance 53