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5. GAS PIPING
1. Size and install the gas supply piping properly in order
to provide a supply of gas sufficient to meet the
maximum demand without undue loss of pressure
between the meter and the boiler.
2. Determine the volume of gas to be provided to the
boiler in cubic feet per hour. To obtain this value,
divide the Btu per hour rating (on the boiler rating
plate) by the heating value of the gas in Btu per cubic
feet. Obtain the heating value of the gas from the gas
supplier. As an alternative, use Table 5.1 on the next
page to obtain the volume of gas to be provided to
the boiler.
3. Use the value obtained above as the basis for piping
sizing. Size the gas piping in accordance with Table
5.2. Consult the National Fuel Gas Code, ANSI
Z223.1/NFPA 54 and/or CAN/CSA B149.1, Natural
Gas and Propane Installation Code.
4. Locate the drop pipe adjacent to, but not in front of
the boiler.
5. Install a sediment trap. See Figure 5.1. Locate a tee in
the drop pipe at same elevation as the gas inlet
connection to the boiler. Extend the drop pipe to a
pipe cap.
6. Install a ground joint union ahead of the gas control
assembly to permit servicing of the control. Some
local codes require an additional service valve when
using the combination gas controls. If your code
requires such a valve, a suggested location is shown in
Figure 5.1.
WARNING
Use a pipe joint sealing compound that is resistant to
the action of liquefied petroleum gas. A non-resistant
compound may lose sealing ability in the presence of
this gas, resulting in a gas leak and fire or explosion
potential.
7. Check piping for leaks prior to placing the boiler in
operation.
Use an approved gas detector, a non-corrosive leak
detection fluid or other leak detection method. If leaks
are found, turn off all gas flow and repair as
necessary.
WARNING
When checking for leaks, do not use matches,
candles, open flames or other methods that provide a
source of ignition. This can ignite a gas leak,
resulting in fire or explosion.
Figure 5.1: Gas Connection to Boiler
8. Disconnect the boiler and its individual shut-off valve
from the gas supply piping system during any pressure
testing of that system at test pressure in excess of 1/2
psig (3.5 kPa).
Isolate the boiler from the gas supply piping system by
closing its individual service valve during any pressure
testing of the gas supply piping system at test pressure
equal to or less than 1/2 psig (3.5 kPa).
CAUTION
Do not subject the gas valve to more than 1/2 psi
(3.5 kPa) pressure. Doing so may damage the valve.
9. Minimum permissible supply pressure for purposes of
input adjustment (Inches Water Column):
Natural Gas
LP Gas
Maximum permissible supply pressure to the boiler
(Inches Water Column):
Natural Gas
LP Gas
GAS PIPING
5.0" (1.2 kPa)
11.0" (2.7 kPa)
13.5" (3.4 kPa)
13.5" (3.4 kPa)
13
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