b) Pressure piping shall conform to the requirements of ANSI
B31.1, Power Piping.
Copper and bronze materials should be avoided for HTW piping.
Expansion should be controlled by the use of expansion loops.
a) All valves should be constructed of cast-steel bodies,
stainless steel trim, and packing such as Teflon.
Bronze-trimmed valves should not be used in HTW systems.
All valves should be capable of being repacked under operating
Gate valves should be used only as generator isolation valves.
e) Any valves other than control valves should have as low a
pressure drop as possible in order to reduce frictional losses and pumping
Space and Process Heating Equipment
Direct Heating with High Temperature Water.
This type of heating
may be achieved by:
a) Unit heaters (usually high velocity type) used in buildings
where the required height for mounting still gives suitable temperatures at
the floor level.
b) Radiant panel heating sometimes used in large spaces where the
mounting height is greater than 10 ft from the floor level. The panels need
to be spread apart so that the radiation is uniformly directed over the spaces
to be heated. With high temperature radiant panel heating, comfort conditions
can be obtained with lower space temperatures than those required for
convection heating. This feature is especially desirable for heating areas
with high ceilings such as a warehouse or hangar.
c) Forced hot air heating systems distribute air throughout the
spaces to be heated. These systems can be equipped with extended surface air
heaters which use HTW as the heating medium.
d) Hospitals, laundries, kitchens and similar facilities utilize
steam. HTW can be used as the heating source provided that steam pressure
beyond the saturation pressure of the HTW plant is not required. This
eliminates separate steam-producing units, traps, and pressure-reducing valves
in the primary circuit. A sudden demand for steam can be handled with the