7
Gas connections
(continued)
Failure to apply pipe sealing compound
as detailed in this manual can result
in severe personal injury, death, or
substantial property damage.
Noble Combi Boilers are typically
shipped ready to fire on natural gas.
Check boiler rating plate to determine
which fuel the boiler is set for. If set to
natural gas, it may be converted to LP
by installing an LP venturi (see page
12). In order to operate on LP gas, an
LP venturi MUST BE installed. Failure
to comply could result in severe personal
injury, death, or substantial property
damage.
Use two wrenches when tightening gas
piping at boiler (FIG. 7-2), using one
wrench to prevent the boiler gas line
connection from turning. Failure to
support the boiler gas connection pipe
to prevent it from turning could damage
gas line components.
DIR #2000528388 00
USE BACK UP WRENCH
TO PREVENT PIPE FROM
ROTATING
Figure 7-2 Inlet Pipe with Backup Wrench
Natural gas:
Pipe sizing for natural gas
1. Refer to Table 7A for pipe length and diameter. Based on
rated boiler input (divide by 1,000 to obtain cubic feet per
hour).
a. Table 7A is only for natural gas with specific gravity
0.60 inches, with a pressure drop through the gas
piping of 0.3 inches w.c.
b. For additional gas pipe sizing information, refer to
ANSI Z223.1 (or B149.1 for Canadian installations).
Natural gas supply pressure requirements
1. Pressure required at the gas valve inlet pressure port:
• Maximum 14 inches w.c. with no flow (lockup) or with
boiler on.
• Minimum 4 inches w.c. with gas flowing (verify during
boiler startup).
2. Install 100% lockup gas pressure regulator in supply line if
inlet pressure can exceed 14 inches w.c. at any time. Adjust
lockup regulator for 14 inches w.c. maximum.
Propane Gas:
Pipe sizing for propane gas
1. Contact gas supplier to size pipes, tanks, and 100%
lockup gas pressure regulator.
Propane Supply Pressure Requirements
1. Adjust propane supply regulator provided by the gas
supplier for 14 inches w.c. maximum pressure.
2. Pressure required at gas valve inlet pressure port:
• Maximum 14 inches w.c. with no flow (lockup) or with
boiler on.
• Minimum 8 inches w.c. with gas flowing (verify during
boiler startup).
Maximum inlet gas pressure must not
exceed the value specified. Minimum
value listed is for the purposes of input
adjustment.
WARNING
WARNING
WARNING
WARNING
Noble Combi Boilers are typically shipped
ready to fire on natural gas. Check boiler
rating plate to determine which fuel the
boiler is set for. If set to natural gas, it may
be converted to LP by installing an LP venturi
(see page 12). In order to operate on LP gas,
an LP venturi MUST BE installed. Failure to
comply could result in severe personal injury,
death, or substantial property damage.
NOTICE
WARNING
Ensure that the high gas pressure regulator
is at least 6 - 10 feet upstream of the
appliance.
45
Installation & Service Manual
F I R E T U B E C O M B I
™
