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B. CONTROL DESCRIPTIONS
See Figure 6.1 in Section 6 (Electrical) for locations of
these devices.
1. FLAME ROLL-OUT SAFETY SHUT-OFF SWITCH
(FLAME ROLL-OUT SWITCH) – A thermally
activated switch located between the first burner
from the left and the manifold bracket. The flame
roll-out safety shut-off switch will sense excessive
temperature caused by continued flame roll-out and
shut down main burner gas. This is a non-recycling
switch that must be replaced once it has been
activated and the cause of the roll-out eliminated.
2. VENT SAFETY SHUT-OFF SWITCH (SPILL
SWITCH) – A thermally activated, manually
resetable switch located in the draft hood relief
opening. If venting system becomes partially or
totally blocked, the vent safety shut-off switch will
sense excessive temperature caused by flue products
exiting the draft hood relief opening and shut down
main burner gas.
3. LIMIT WITH LOW WATER CUT-OFF – A Beckett
7600B or Hydrolevel 3200 control incorporate a
thermally activated adjustable switch that will shut
down main burner gas if the supply water temp
exceeds the control setting. It will also shut down
main burner gas if the water level in the boiler drops
below the control's sensing well. The temperature
switch will automatically reset when the boiler supply
water temp drops below the control setpoint. The
low water cut-off switch will automatically reset when
the water level is above the control's sensing well.
4. LOW WATER CUT-OFF (FOR GRAVITY SYSTEMS
OR HOT WATER BOILERS INSTALLED ABOVE
RADIATION LEVEL) – If limit control does not
incorporate a low water cut-off feature then install a
level-sensing device (float or probe) located in supply
piping near the boiler.
C. ADJUSTMENT OF GAS PRESSURE
REGULATOR
1. Using the manometer setup installed in part 7A, set
manifold pressure as follows for various gases.
a. Natural Gas . . .3.5" Water Column (0.9 kPa)
b. LP Gas . . . . .10.0" Water Column (2.5 kPa)
2. To adjust gas pressure, turn adjusting screw of gas
pressure regulator counterclockwise to decrease
pressure, clockwise to increase pressure. Refer to
Figure 7.2 for location of gas pressure regulator.
Replace the cap screw when adjustment is complete.
3. In no case should the final manifold pressure vary
more than ±0.3 inches water column (0.07 kPa)
from the above specified pressures. Any necessary
major changes in the flow should be made by
changing the size of the burner orifice spuds.
4. When adjustment is complete, turn off boiler, gas
flow and electricity to boiler. Remove manometer
connection from valve and plug tapping with plug
provided. Turn utilities back on and resume
checkout.
INSTALLATION AND OPERATING INSTRUCTIONS
D. CHECKING BURNER INPUT
1. Refer to rating label mounted on the jacket top panel
to obtain the rated BTU per hour input. In no case
shall the input to the boiler exceed the value shown
on the rating label.
2. Check input by use of the following formulas:
U.S. Customary Units
Input (BTU/Hr.)= 3600 x F x H
Where:
3600 = Seconds per hour
F = Cubic Feet of Gas Registered on Meter
H = Heat Value of Gas in BTU/Cubic Feet
T = Time in Seconds the Meter is Read
SI Metric Units
Input (kW)= 3600 x F x H
Where:
3600 = Seconds per hour
3.6 = Megajoule (MJ) per kilowatt hour (kwhr)
F = Cubic Meters of Gas Registered on Meter
H = Heating Value of Gas in MJ/Cubic Meter
T = Time in Seconds the Meter is Read
3. As an alternative, use Table 7.1(a) and 7.1(b). Use
the heating value provided by gas supplier. Use a
stopwatch to record the time it takes for 2 cubic feet
(0.0566 cubic meter) of gas to pass through the
meter. Read across and down to determine rate.
Table 7.1a: Meter Conversion – Natural Gas
(U.S. Customary Units)
Burner inputs in Btu/hr for various meter timings and heat
values. (Table based on 2 cubic feet of gas through merter).
Time that
meter is
read (sec)
1000
25
288000
30
240000
35
205714
40
180000
45
160000
50
144000
55
130909
60
120000
65
110769
70
102857
75
96000
80
90000
85
84706
90
80000
95
75789
100
72000
105
68571
110
65455
115
62609
120
60000
125
57600
T
T x 3.6
Heat Value of Gas
(Btu/cubic foot)
1025
1050
295200
302400
246000
252000
210857
216000
184500
189000
164000
168000
147600
151200
134182
137455
123000
126000
113538
116308
105429
108000
98400
100800
92250
94500
86824
88941
82000
84000
77684
79579
73800
75600
70286
72000
67091
68727
64174
65739
61500
63000
59040
60480
23
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