Slant/Fin Gas Hot Water - Manual (Page 11)

10 20 30 40 50 60 70
1/4 .364 32 22 18 15 14 12 11
3/8 .493 72 49 40 34 30 27 25
1/2 .622 132 92 73 63 56 50 46
3/4 .824 278 190 152 130 115 105 96
1 1.049 520 350 285 245 215 195 180
1 1/4 1.380 1,050 730 590 500 440 400 370
1 1/2 1.610 1,600 1,100 890 760 670 610 560
2 2.067 3,050 2,100 1,650 1,450 1,270 1,150 1,050
2 1/2 2.469 4,800 3,300 2,700 2,300 2,000 1,850 1,700
3 3.068 8,500 5,900 4,700 4,100 3,600 3,250 3,000
4 4.026 17,500 12,000 9,700 8,300 7,400 6,800 6,200
80 90 100 125 150 175 200
1/4 .364 11 10 9 8 8 7 6
3/8 .493 23 22 21 18 17 15 14
1/2 .622 43 40 38 34 31 28 26
3/4 .824 90 84 79 72 64 59 55
1 1.049 170 160 150 130 120 110 100
1 1/4 1.380 350 320 305 275 250 225 210
1 1/2 1.610 530 490 460 410 380 350 320
2 2.067 990 930 870 780 710 650 610
2 1/2 2.469 1,600 1,500 1,400 1,250 1,130 1,050 980
3 3.068 2,800 2,600 2,500 2,200 2,000 1,850 1,700
4 4.026 5,800 5,400 5,100 4,500 4,100 3,800 3,500
11
Table 5. Characteristics of various fuel gases Table 6. Gas main sizing guide
Natural 1000 Btu 1.00
Propane 2500 Btu 1.10
Type
of Gas
Heating
Valve*†
Flow
Correction
Factor
* per cubic foot
† Consult fuel supplier for actual BTU value.
Nominal
Iron Pipe
Size
Inches
Internal
Diameter
Inches
Equivalent
Length of Pipe, Feet
Maximum capacity of pipe in cubic
feet of gas per hour for gas pres-
sures of 0.5 psig or less and a
pressure drop of 0.3 inch water
column (based on a 0.60 specific
gravity gas).
CONTROLS
THE BOILER STAGING CONCEPT
The heart of the Caravan boiler plant is a temperature-actuated
control system that automatically stages only those boiler
modules needed to meet the heating demand in a given period,
thereby conserving fuel.
In a staging control system, each stage ordinarily activates one
boiler module. With appropriate wiring, multiple modules can be
grouped within a stage.
During a fluctuation in heating requirements, a large central boiler
cycles on and off to match heat output to building demand. A
staged modular boiler system, on the other hand, will energize
only as many modules as the system load requires. Only one
stage cycles at a time. The other stages remain off or operate
continuously, thereby performing at peak efficiency. For example,
in a 10 module boiler system, with the heating load at 61% of
capacity, six of the modules operate continuously at peak
efficiency. Fractional heating requirements are supplied by the
seventh "cycling" module, while the remaining three modules are
"off." This is in contrast to a single large central boiler that simply
cycles on and off, resulting in lower efficiency.
Over-sizing is a major factor in poor system efficiency. Most of the
time a single central boiler is oversized. Historical data shows
that many single central boilers are considerably oversized even
at the outdoor temperature for which they were designed.
Modular boiler systems are not oversized by more than a portion
of one module, regardless of the load.
The Caravan control system automatically compensates for
seasonal temperature changes. It energizes more or fewer
modules depending on changes of outside temperature, system
water temperature, or both. Modules save energy by operating in
long cycles at full-rated output and maximum efficiency.
CONTROL SYSTEM SELECTION
Slant/Fin offers two controls to step fire a hot water Caravan sys-
tem. The SC-3 and SC-9 controls fulfill a wide range of applica-
tions. They control the boiler system and are not intended to be
the sole building temperature control. They do not replace zoning
the system or the thermostats that control these zones.
SC-3 Control
The SC-3 control allows up to 3 stages in a Caravan system.
Generally each stage controls 1 module. However, it is possible to
have more than 1 module activated with each stage.
Standard programmable features include: system activation or
de-activation based on outdoor temperature; minimum target
supply water temperature; adjustable design target supply water
temperature; adjustable delay between stages; adjustable
outdoor temperature and indoor design temperatures.
The view menu on the control includes error messages, actual
outdoor air temperature, actual supply water temperature,
target supply water temperature and running time for each stage.