Finned copper tube gas boilers & water heaters – Boiler Manual
21
GAS SUPPLY PIPING
Check the boiler/water heater rating plate to make sure
that the boiler/water heater is for the type of gas that will
be used. If it isn’t, do not connect the boiler/water heater
to the gas supply. Gas supply piping must be in
accordance with the National Fuel Code, ANSI Z223.1-
latest revision or applicable provisions of the local
building codes. Canadian installations must comply
with CAN/CGA B149.1 or .2 Installation Code. Failure
to comply with this warning can result in extensive
property damage, severe personal injury or death!
The Dominator comes from the factory ready to be piped to the
gas supply. If for any reason the boiler/water heater is not for the
type of gas available at the installation site, call your RBI representative
to resolve the problem.
A minimum gas supply pressure of
6 in
,
152 mm
WC natural or
11 in
,
279 mm
WC propane and
maximum
14 in
,
356 mm
WC natural or propane,
must be available at the safety shutoff valve inlet with
the unit(s) operating.
Table 9 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
9 should be used in conjunction with Table 10 to ensure that the gas
supply piping has the capacity to meet the demand.
Figure 16 depicts the proper way to connect the boiler/ water heater
to the gas supply piping. The manual shut-off valve must be installed
in the supply piping. It should be installed
5 ft
,
1.5 m
above the floor
where required by local codes. Provide a sediment trap at the bottom
of the vertical section of the gas supply pipe upstream of the gas
controls.
A ground joint union should be installed between the boiler gas
controls and the supply piping. Each of these items are needed to
ensure long life and ease of servicing. Always use a pipe sealant that
is suitable for use with LP gas.
Table 9 Gas Pipe Capacity
Maximum pipe capacity in ft
3
/hr based on 0.60 specific gravity gas
at a pressure of 0.5 psig or less and a 0.3" WC pressure drop.
Nominal
Iron Pipe
Size
Pipe length in feet
10
20
30
40
50
60
80
100
150
Maximum gas volume of pipe, (ft
3
/hr)
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
2"
3050 2100 1650 1450 1270 1150 990
870
710
2 1/2"
4800 3300 2700 2300 2000 1850 1600 1400 1130
3"
8500 5900 4700 4100 3600 3250 2800 2500 2000
Note: Multiply the gas volume by 0.62 for propane flow capacity in ft
3
/hr.
Multiply the propane flow capacity by 2500 Btu/ft
3
to determine
the propane Btu/hr capacity for a given pipe size and length.
Table 10 Equivalent Pipe Length Chart
Nominal
Iron Pipe
Size
Type of pipe fitting
90˚ Elbow
Tee
1
Gate Valve
2
Gas Cock
2
Equivalent pipe length, (ft)
1"
2.6
5.2
0.6
1.5
1 1/4"
3.5
6.9
0.8
1.9
1 1/2"
4.0
8.0
0.9
2.3
2"
5.2
10.3
1.2
3.0
2 1/2"
6.2
12.3
1.4
3.7
3"
7.7
15.3
1.8
4.5
Notes:
1. For flow through branch.
2. For flow at full open.
Always use a square jawed wrench on the gas valve
body when making gas connections to it. Never over-
tighten the piping entering the gas valve body or gas
valve failure may result!
Figure 16
Gas Supply Piping
When applicable, provisions for vent, bleed and gas relief lines must
be made in accordance with the latest revision of ANSI Z223.1/
NFPA 54.
Safe lighting and other performance criteria were met with the gas
manifold and control assembly provided on the boiler. All gas
connections MUST be leak tested before putting the boiler into
operation.
Never use an open flame to test for gas leaks. Always
use an approved leak detection method. Failure to
comply with this warning can cause extensive property
damage, severe personal injury or death!
Whenever the gas supply piping is pressure tested the boiler/water
heater gas controls must be protected. If the test pressure is equal to,
or less than
1/2 psig
,
3.5 kPa
isolate the boiler/water heater by
closing it's manual shut off valve, see Figure 16. If the test pressure is
greater than, or equal to
1/2 psig
,
3.5 kPa
, disconnect the boiler/
water heater and its individual shut-off valve.
