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GB100W NATURAL OR PROPANE BOILER
INSTALLATION AND OPERATING INSTRUCTIONS
GAS SUPPLY PIPING
WARNING: All gas piping must be installed by a
qualified technician in accordance with the
provisions set forth in the latest revision of ANSI
Z223.1 and all applicable local building codes
and regulations. All LP gas connections must
be made by a licensed propane installer. Failure
to comply with this WARNING can result in
extensive property damage, severe personal
injury or death!
The GB100W hot water boiler comes from the factory
ready to be piped to the gas supply.
WARNING: Check the boiler rating plate to make
sure that the boiler is for the type of gas that will
be used. If it isn’t, do not connect the boiler to
the gas supply. Failure to comply with this
warning can result in extensive property
damage, severe personal injury or death!
If for any reason the boiler is not for the type of gas
available at the installation site, call the nearest Smith
Cast Iron Boiler distributor to resolve the problem.
Table 3 should be used to ensure that the gas supply
piping is sized properly. If more than one appliance is
supplied by the same supply pipe, the piping must be
sized based on the maximum possible demand. Do not
neglect the pressure drop due to pipe fittings. Table 4
should be used in conjunction with Table 3 to ensure
that the supply piping has the capacity to meet the
demand.
Table 3: Gas Pipe Capacity
Table 4: Equivalent Length Chart
Reverse Acting Aquastats
An alternative for existing systems experiencing
condensation that does not require re-piping the boiler
utilizes a reverse acting aquastat, one that makes on
temperature rise. This approach works best in single
zone systems. Wired in series with the circulator, this
control holds the circulator off until the boiler reaches
an acceptable temperature and then starts system
circulation, see Figure 10.
The most commonly available reverse acting aquastat
is a Honeywell L4006B. The aquastat should be
mounted in an immersion well directly installed in the
boiler. The use of heat conductive grease, Honeywell
part # 972545, in the immersion well is strongly
recommended for fast and accurate temperature
response. Set this adjustable aquastat to make at no
less than 130° F,
54
°
C
. While this method can cause
the circulator to cycle more frequently, setting the
aquastat’s differential to the maximum 25-30°F will
minimize short cycling.
Figure 10: Reverse Aquastat
reverse
aquastat
N.O.
T
T
t'stat
GV
115 volts
24 volts
circulator
operating
aquastat
N.C.
REVERSE
AQUASTAT
SET AT 120° F
Eqivalent length of pipe fittings in feet
Nominal Type of pipe fitting
Iron Pipe 90° Elbow Tee Gate Valve Gas Cocks
Size (flow thru branch) (full port)
(inches.) Equivalent length in feet
3/4" 2.06 4.12 0.48 1.25
1" 2.62 5.24 0.61 1.60
1-1/4" 3.45 6.90 0.81 2.15
1-1/2" 4.02 8.04 0.94 2.50
Maximum pipe capacity in ft
3
/hr based on 0.60 specific gravity gas
at pressure of 0.5 psig or less and a 0.3" W.C. pressure drop.
Nominal Pipe length in feet
Iron Pipe 10 20 30 40 50 60 80 100 150
Size (in.) Maximum gas volume in cubic feet/hr, (ft
3
/hr)
3/4" 278 190 152 130 115 105 90 79 64
1" 520 350 285 245 215 195 170 150 120
1-1/4" 1050 730 590 500 440 400 350 305 250
1-1/2" 1600 1100 890 760 670 610 530 460 380