Page 149 - Boiler_Operators_Handbook,_Second_Edition

134 Boiler Operator’s Handbook

cycling is a normal condition. visual inspection by a National Board Certified Inspec-
In case you haven’t already figured it out, I dislike tor before the certificate to operate is issued.
steam powered instantaneous hot water heaters because Initial operation of the burner should be achieved
they produce load swings in the summer that prevent under the supervision of a technician trained in the
smooth and constant operation of the boilers. Now that proper set up of a fired piece of equipment. That techni-
I’ve made my position clear (that storage is a necessity) cian should produce a “start-up sheet,” a document that
it’s time to talk about operation and control of hot water includes, as minimum: The name, address, and phone
heaters. number of the technician’s employer, the technician’s
Figure 4-9 is a graphic of a boiler and storage tank name and signature, and the date the initial start-up was
system typical of that used in a large apartment building. performed; a record of the actual settings of the operating
Cold city water enters the system at the bottom center of limit (OL) and the high limit (HL) temperature switches
the graphic where it can either enter the circulating pump and an indication that their operation was confirmed; a
or the storage tank. Service water is drawn off the top of record of the setting of the pressure-temperature relief
the tank. The arrow at the bottom right side of the tank valve and a record that its operation was confirmed; a
represents flow of water circulated through the system to record of the burner performance while firing including,
maintain hot water in the piping distribution system. but not necessarily limited to: stack temperature, flame
This combination of heater and storage will cycle signal measurement, percent oxygen in flue gas, carbon
but it has the advantage of extended cycle operation and monoxide level of flue gas, if measured, smoke spot test
a fixed firing rate for the burner that makes it efficient, recording (oil only) if measured, gas consumption rate
but still simple to operate and maintain, if you know (gas firing), temperature of water at the boiler inlet dur-
what you’re doing. ing normal operation, temperature of water at the boiler
A service water boiler deserves the same attention outlet during normal operation, pressure at the inlet
as a heating boiler on initial start-up. Before the system of the system, pressure at the discharge of the pump
is started the owner, design engineer or installing con- or other location between pump and boiler, and posi-
tractor (depending upon the requirements associated tion of the throttling valve. The start-up sheet should
with installation) should contact the owner’s insurance be retained as a part of the original documentation for
company or the authority having jurisdiction (normally the system and referenced on each subsequent start-up
the state, county or municipality) to obtain a boiler cer- (after shutdowns for maintenance or other purposes) to
tificate (or a document of similar title) which authorizes ensure the conditions do not differ substantially from
the owner to operate the boiler. There may be provisions the original start-up conditions.
in the jurisdiction to exempt certain equipment but any All openings into the boiler and tank should be
requirements should be determined before placing the checked to ensure the system is closed and will not lose
system in service. Normally the boiler is subjected to a water unintentionally when placed in service. Before
closing openings the internals should be inspected to
ensure there are no loose parts, tools, personnel, or any-
thing else inside the system that does not belong there.
Valves and some spigots are opened to vent air and
admit water until the system is flooded and at city water
pressure. It is important to note that, if the city water
supply to the inlet shown in the graphic is separated
from the city water supply by a check valve or back-
flow preventer, an expansion tank or similar provision
is required to prevent an increase in the system pressure
when the water expands as it is heated.
Disconnects, circuit breakers, and control switches
are closed (in that order) to permit system operation.
The circulating pump should start first, followed by the
burner. The start-up sheet should be checked as soon as
operation stabilizes to ensure the conditions do not dif-
fer substantially from the original start-up conditions.
Figure 4-9. Service water heating system Since the first edition of this book was written the