49
8
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.
Use two wrenches when tightening gas
piping at boiler (FIG. 8-3), 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 #2000588342 00
USE BACK-UP WRENCH TO
PREVENT PIPE FROM ROTATING
Figure 8-3
Inlet Pipe with Back-up Wrench
Natural gas:
Pipe sizing for natural gas
1. Refer to Table 8A for pipe length and diameter. Based on
rated boiler input (divide by 1,000 to obtain cubic feet per
hour).
a. Table 8A 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. (3.5 kPa) with no flow
(lockup) or with boiler on.
• Minimum 4 inches w.c. (.99 kPa) 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. (3.5 kPa) at any
time. Adjust lockup regulator for 14 inches w.c. (3.5 kPa)
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. (3.2 kPa) maximum pressure.
2. Pressure required at gas valve inlet pressure port:
• Maximum 14 inches w.c. (3.2 kPa) with no flow (lockup)
or with boiler on.
• Minimum 8 inches w.c. (1.9 kPa) 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
NOTICE
⚠
WARNING
Ensure that the high gas pressure regulator
is at least 10 feet (3 m) upstream of the
appliance.
Installation & Operation Manual
⚠
WARNING
Knight XL 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 a LP venturi
and making a gas valve adjustment (see
pages 13 and 14). In order to operate on LP
gas, an orifice MUST BE installed (for 500
models) or a gas valve adjustment MUST
BE made. Failure to comply could result in
severe personal injury, death, or substantial
property damage.
