accumulator of the heat generated and helps equalize the heating load on the
(g) Negligible System Losses. The system is closed and is under
c o n s t a n t pressure at all times, which eliminates flashing.
( h ) Simplified Distribution System. H T W distribution lines can follow
t h e natural land contours (refer to paragraph 4.1). This and the elimination
o f traps, pressure reducing valves, and condensate return pumps makes for a
s i m p l i f i e d system.
( 1 ) F l e x i b i l i t y . HTW can be used directly at full temperatures for
space and process heating or indirectly through converters to produce
low-pressure hot water or steam.
Ease of operation and control is
( j ) Ease of Operation and Control.
S i m p l i f i c a t i o n of valves and fittings.
Absence of traps, pressure reducing valve stations, and
condensate return pumps.
Feedwater treating equipment of simple design.
Central pump location. Pumps are installed in the central
heating plant and are not dispersed throughout the system.
Uniform temperature is as easily maintained in normal
operation as during peak loads.
( k ) Safety of Operation. Water leaking from an HTW line rapidly expands
to atmospheric pressure, c a u s i n g a refrigerating effect; the leaking water is
further cooled by evaporation. This permits holding the hand within 1 or
2 feet of a small leak without being burned. Also, the amount of HTW at
saturation temperature that can pass through an opening in a given time is
about one-half the amount of steam which could pass through the same opening.
3 REFERENCE DESIGN SPECIFICATIONS. Design standards and recommendations for
HTW distribution systems are contained in NAVFAC DM-3, Design Manual,
Mechanical Engineering ; and NAVFAC DM-3.8, Design Manual, Exterior
Distribution of Utility Steam, High Temperature Water (HTW), Chilled Water
(CHW), Fuel Gas, and Compressed Air.