45
GAS-FIRED BOILER Boiler Manual
A. GAS CONNECTION
The gas supply shall have a maximum inlet
pressure of less than 14" water column (350
mm), ½ pound pressure (3.5 kPa), and a mini-
mum of 3.5" water column. The entire piping
system, gas meter and regulator must be sized
properly to prevent pressure drop greater than
0.5" as stated in the National Fuel Gas Code. This
information is listed on the rating plate.
The nipple provided is ½" with a factory installed
3/4" bell reducer. Do not remove this ¾" x ½" bell
reducer! It is mandatory that this fitting is used
for connection to a field fabricated drip leg as
shown in the illustration above per the National
Fuel Gas Code. You must ensure that the entire
gas line to the connection at the Munchkin is no
smaller than ¾". Once all the inspections have
been performed, the piping must be leak tested.
If the leak test requirement is a higher test pres-
sure than the maximum inlet pressure, you must
isolate the Munchkin from the gas line. In order
to do this, you must shut the gas off using fac-
tory and field-installed gas cocks. This will pre-
vent high pressure. Failure to do so may dam-
age the gas valve. In the event the gas valve is
exposed to a pressure greater than ½ PSI, 14"
water column, the gas valve must be replaced.
Never use an open flame (match, lighter, etc.) to
check gas connections.
B. GAS PIPING
1. Run the gas supply line in accordance with all
applicable codes.
2. Locate and install manual shutoff valves in
PART 8: GAS PIPING
accordance with state and local
requirements.
C. GAS TABLE
Refer to Table 8.1 to size the supply piping to
minimize pressure drop between meter or
regulator and unit.
Maximum Capacity of Pipe in Cubic Feet of Gas
per Hour for Gas Pressures of 0.5 psi or Less and
a Pressure Drop of 0.3 Inch water Column
Table 8-1 (Based on a 0.60 Specific Gravity Gas)
It is recommended that a soapy solution be used
to detect leaks. Bubbles will appear on the pipe to
indicate a leak is present. The gas piping must be
sized for the proper flow and length of pipe, to
avoid pressure drop. Both the gas meter and the
gas regulator must be properly sized for the total
gas load. If you experience a pressure drop greater
than 1" WC, the meter, regulator or gas line is
undersized or in need of service. You can attach a
manometer to the incoming gas drip leg, by
removing the cap and installing the manometer.
The gas pressure must remain between 3.5" and
14" during stand-by (static) mode and while in
operating (dynamic) mode. If an in-line regulator
is used, it must be a minimum of 10 feet from the
Munchkin. It is very important that the gas line is
properly purged by the gas supplier or utility.
Failure to properly purge the lines or improper
line sizing, will result in ignition failure. This
problem is especially noticeable in NEW LP
installations and also in empty tank situations. This
can also occur when a utility company shuts off
WARNING
Failure to follow all precautions could result in
fire, explosion or death!
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WARNING
It is very important that you are connected to
the type of gas as noted on the rating plate. "LP"
for liquefied petroleum, propane gas or, "Nat"
natural or city gas. All gas connections must be
approved by the local gas supplier, or utility in
addition to the governing authority, prior to
turning the gas supply on.