CHAPTERS
The adjustment procedures in this chapter apply
to standard components furnished
on
steam
or
hot water boilers fired with gas and/or the various
grades
of
oil.
High Turndown
Burner
In order to reduce burner cycling and to improve
operating efficiency, burners have been designed
for enhanced fuel turndown capabilities.
A High
Turndown Burner
(IITB) is installed
on
250
Hp
to 800 Hp boilers equipped to fire light oil (Series
1
00),
or
gas, (Series 700),
or
both (Series 200).
On
the High Turndown Burner, air and fuel
inlets, the diffuser, and the air
damper
control
linkage are designed for higher turndown perfor-
mance.
The
High Turndown Burner
can
be identified
from the natural gas housing, which is spudded,
and the burner diffuser, which. has a circular
pattern
of
5/8" holes around the front fmned face.
CAUTION!
Observe
that
proper
air
damper
linkage
and
fuel
metering
ad-
justment
procedures
are
fol-
lowed
for
standard
(Series 400
or
SOO)
or
HTB (Series 1 00, 200
or
700)
burners
to
avoid
damage
to
the
equipment.
The
burner
series·
is
identified
on
the
boiler
data plate
affixed
to
the
front
head
of
the
boiler.
Contact your local Cleaver-Brooks authorized
Representative for recommendations covering
special controls that are not included in this
chap-
ter.
750-150
ADJUSTMrnNTPROCEDURES
B. UNKAGE-MODULATING
IVIOTOR
AND
AIR DAMPER
The
linkage consists
of
various arms, connecting
rods, and swivel ball joints that transmit motion
from the modulating
motor
to the metering
cam(s), to the rotary air damper, and to the gas
butterfly valve,
if
used.
When properly adjusted, a coordinated move-
ment
of
the damper and metering cams within the
limits
of
the modulating motor
trav~l
is attained
to provide proper fu.el-air ratios through the firing
range.
In linkage adjustments, there are several impor-
tant factors that must serve
as
guides.
(a)
The
modulating motor must
be
able to
complete its
full
travel range.
CAUTION!
Restriction
of
full
travel
will
cause
definite
damage
to
this
motor.
b) Initial adjustment should
be
made with
the motor in full closed position, that
is
with the shaft
on
the power end
of
the
motor in its most counterclockwise posi-
tion.
(c)
The
closer the connector is to the drive
shaft the less the
ann
will travel, while the
closer the connector is to the driven shaft
the farther that arm will travel.
(d)
Over-travel
linkage, where used,
should not
be
required to extend its spring
to fullest stretch.
CHAPTER
S--3
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