The controller shall be of sturdy construction and shall be protected
against dust and dampness. The thermostatic element shall be inserted in a
separable socket installed [in the upper part of the boiler near the water
outlet] [in the boiler return piping]. [Fixed position (on-off) and three
position (high-low-off) controller shall operate on a 5.56 degree C 10
degree F differential over an adjustable temperature range of approximately
60 to 104.4 degrees C 140 to 220 degrees F.] [Modulating controllers shall
control the fuel burning equipment to maintain set boiler water temperature
within 2 percent.] [Controller shall be furnished with necessary equipment
to automatically adjust the setting to suit the outside weather conditions.
The outside air reset controller shall be operated in such a manner that
the operating temperatures required by the boiler manufacturer are not
compromised.]
2.3.4
Steam Pressure Controller
**************************************************************************
NOTE: If steam boilers are not utilized the
following paragraph will be deleted.
**************************************************************************
The controller shall be of sturdy construction and shall be protected
against dust and dampness. The sensing elements of the steam controller
shall be in direct contact with the steam. [Fixed position (on-off) and
three position (high-low-off) type controllers shall operate on a 6.9 kPa
(1 pound) 1 pound differential over a pressure range of 0 to 103.4 kPa (0
to 15 psig) 0 to 15 psig.] [Modulating controllers shall automatically
maintain, within 2 percent, the desired steam pressure by regulating the
burner.]
2.3.5
Boiler Plant Master Controller
**************************************************************************
NOTE: If only one boiler is utilized, the following
paragraph will be deleted. A master controller will
be provided for applications involving multiple
boilers and for boilers arranged in a modular
configuration.
**************************************************************************
A boiler plant master controller, sensitive to a [temperature transmitter
in the return water header for the boiler] [steam pressure transmitter in
the boiler steam discharge header] shall be furnished to provide
anticipatory signals to all boiler controllers. Boiler controllers shall
react to anticipatory signals from the plant master controller as necessary
in response to the boiler [temperature] [pressure] indication to maintain
the preset [temperature] [pressure]. An automatic-manual switch shall be
provided to allow the sequence of boiler loading to be varied to distribute
equal firing time on all boilers in the plant. The plant master controller
shall load the boilers one at a time as the plant load increases.
2.3.6
Boiler Combustion Controls and Positioners
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NOTE: A pilot is required for all oil fired boilers
over 875 kW (3,000,000 Btuh). However, a pilot is
recommended for all fired boilers.
SECTION 15569A
Page 28
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