750-368
CBEX Elite 100-1200 HP
3-3
3.2 — Water Requirements
Water Circulation
The Maximum Circulating Rate Chart, Figure 3-2, shows the maximum gpm circulation rate of boiler water in
relation to full boiler output and system temperature drop.
FIGURE 3-2. Maximum Circulating Rate Chart
Multiple Boiler Installations
When multiple boilers are used, care must be taken to ensure adequate or proportional flow through the boilers.
Proportional flow can best be accomplished by use of balancing valves and gauges in the supply line from each
boiler. If balancing valves or orifice plates are used, a significant pressure drop (e.g., 3-5 psi) must be taken
across the balancing device to accomplish the purpose.
If care is not taken to ensure adequate or proportional flow through the boilers, wide variations in firing rates
between the boilers can result.
In extreme cases, one boiler may be in the high-fire position while the other boiler or boilers may be at low fire.
The net result would be that the common header water temperature to the system would not be up to the desired
point.
Pump Location
It is recommended that the system circulating pumps take suction from the outlet connection on the boiler, and
that they discharge to the system load. The suction side is preferred because it decreases air entry into the sys-
tem and does not impose the system head on the boiler.
NOTE: The circulating pumps should be interlocked with the burner so that the burner cannot operate unless the cir-
culating pump is running in order to avoid damage to the equipment.
BHP
Boiler Output
MBTU/hr
System Temperature Drop - Degrees F
10 20 30 40 50 60 70 80 90 100
Maximum Circulating Rate - GPM
100 3,350 670 335 223 168 134 112 96 84 75 67
125 4,185 836 418 279 209 168 140 120 105 93 84
150 5,025 1,005 503 335 251 201 168 144 126 112 100
200 6,695 1,340 670 447 335 268 224 192 168 149 134
250 8,370 1.675 838 558 419 335 280 240 210 186 167
300 10,045 2,010 1,005 670 503 402 335 287 251 223 201
350 11,720 2,350 1,175 784 587 470 392 336 294 261 235
400 13,400 2,680 1,340 895 670 535 447 383 335 298 268
500 16,740 3,350 1,675 1,120 838 670 558 479 419 372 335
600 20,080 4,020 2,010 1,340 1,005 805 670 575 502 448 402
700 23,430 4,690 2,345 1.565 1,175 940 785 670 585 520 470
800 26,780 5,360 2,680 1,785 1,340 1,075 895 765 670 595 535
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