OPERATION OF HTW DISTRIBUTION SYSTEMS
1 OVERVIEW. Operating procedures for HTW and steam distribution systems are
s i m i l a r . Although HTW systems do not have traps, condensate pockets, pressure
r e d u c i n g valve stations, or condensate return pumps, high points in the system
m u s t be vented periodically to relieve air accumulation.
2 STARTUP INSPECTION. Before placing a new HTW distribution system in
service, or after a major overhaul to an existing system, make sure the
f o l l o w i n g requirements are fulfilled.
(a) System meets all applicable requirements as listed In approved
( b ) Applicable field tests have been satisfactorily completed.
( c ) A l l i n s t a l l a t i o n , r e p a i r : and cleanup work is completed, including
c l e a n i n g and flushing of heat carrier pipes.
( d ) All conduits and passages are free of obstructions and are tight.
( e ) All insulation is correctly installed, dry, and in good condition.
( f ) All auxiliary equipment is correctly installed and ready for
o p e r a t i o n . A u x i l i a r y equipment, i n c l u d i n g pumps, strainers, drains, vents,
and expansion joints, is discussed in chapter 6 of this manual.
(g) HTW generators and accessory equipment are ready for operation.
3 SYSTEM STARTUP. Before starting up the system, notify the HTW generating
station and the HTW consumers. Prepare a starting schedule and supply it to
all interested parties so that adequate preparations may be made.
3.1 Startup Procedure for Combined Pumping Systems. Proceed as follows to
start a cold system.
(a) Make sure that proper water level is carried in the system expansion
(b) Open inlet and outlet valves for the HTW generators, expansion tank,
a n d distribution system.'
(c) Open water inlet valve to combination pumps.
( d ) Open pump vents until all air is released; then close vents.
( e ) Start the pumps, then slowly open the discharge valve. Check pumps
and drives for any abnormal condition such as excessive vibration, noise, or
unusual temperature. C h e c k lubrication.
(f) Check and adjust waterflow through HTW generators until all boiler
flows are equalized at a correct value.
(g) Vent air from headers and high points in the system.