CHAPTER!
GENERAL
DESCRIPTION
AND
PRINCIPLES
OF
OPERATION
A drip pan elbow
or
a flexible connection be-
tween the valve and the escape pipe
is
recom-
mened (see Fig. 1-9). The discharge piping must
be
properly arranged and supported so that its
weight does not bear upon
~e
valve.
Do
not paint, oil,
or
otherwise covery any interior
or working parts
of
the safety valve. A valve does
not require any lubrication
or
protective coating
to work properly.
!WARNING
Only properly certified personnel
such
as
the
safety
valve
manufacturer's
certified
repre-
sentative
should
adj~st
or
repair
the
boiler safety valves. Failure
to
heed
this
warning could result in
serious
personal
injury
or
death.
F.
HOT
WATER
CONTROLS
(ALL
i=UELS)
(1) Water Temperature Gauge (Fig. 1-2): Indi-
cates
water temperature in the boiler.
(2) Water Pressure Gauge (Fig.
1-2): Indicates
water pressure in the boiler.
(3) Operating Limit Temperature Control (Fig.
1-2): Breaks a circuit
to
stop the burner operation
on a rise
of
boiler temperature above a selected
setting.
It
is adjusted to stop
or
start the burner at
a preselected operating temperature.
(4) High Limit Temperature Control (Fig. 1-2):
Breaks a circuit
to
stop the burner operation on a
rise
of
temperature above a selected setting. It
is
adjusted
to
stop the burner at a preselected
temperature above the operating control setting.
The high limit temperature control normally
is
equipped with a manual reset.
CHAPTER
1...S
(5) Modulating Temperature Control (Fig. 1-2):
Senses changing boiler temperature and trans-
mits this information
to
the modulating motor to
change the burner's frring rate when the
manual-
automatic switch
is
set on automatic.
(6)
low
Water Cutoff (Fig. 1-2): Breaks the
circuit to stop the burner operation
if
the water
level in the boiler drops below a safe operating
level, activating the low water light and optional
alarm bell
if
the boiler
is
so equipped.
(7) Auxiliary
low
Water Cutoff (Not Shown)
(Optional): Breaks the circuit
to
stop the burner
operation
if
the water level in the boiler drops
below the master low water cutoff point.
(8) Relief Valve(s) (Fig. 1-2): Relief valve(s)
relieve the boiler
of
pressure higher than the
design pressure (or a lower pressure,
if desig-
nated). Relief valves and their discharge piping
are
to
be installed
to
conform
to
ASME code
requirements.
!WARNING
.Only properly certified personnel
such as
the
relief valve manufac· ·
turer's
certified
representative
should adjust
or
repair
the
boiler
relief valves. Failure
to heed
this
warning
could
result In serious
personal
injury
or
death.
G.
CONTROLS
FOR
GAS
FIRING
Depending upon the requirements
of
the in·
surance carrier
or
other governing agencies, the
gas
flow control system,
or
gas train, may consist
of
some,
or
all,
of
the following items. Refer
to
the Dimension Diagram (DD) prepared by
Cleaver-Brooks for your specific installation. A
typical gas train
is
shown
in
Fig. 1-3.
750-150
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