32
Installation & Operation Manual
6
Gas connections
Use two wrenches when tightening gas
piping at boiler (FIG. 6-2), 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.
USE BACK UP WRENCH TO PREVENT
PIPE FROM ROTATING
Figure 6-2 Inlet Pipe with Backup Wrench
3. Install 100% lockup gas pressure regulator in supply line for
each boiler if inlet pressure exceeds 14 inches w.c. (3.5 kPa).
4. Gas valves used on Crest boilers are rated for at least 27
inches w.c. (6.7 kPa).
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. Target a supply pressure of 11 inches w.c. (2.7 kPa)
measured when the boiler is operating at minimum input
rate. Gas pressure can be adjusted higher or lower than 11
inches w.c. as needed.
2. Adjust propane supply regulator provided by the gas
supplier for 14 inches w.c. (3.5 kPa) maximum pressure.
3. Pressure required at gas valve inlet pressure port:
• Maximum 14 inches w.c. (3.5 kPa) with boiler operating.
• Minimum 4 inches w.c. (.99 kPa) with boiler operating.
Maximum inlet gas pressure must not
exceed the value specified. Minimum
value listed is for the purposes of input
adjustment.
WARNING
WARNING
NOTICE
Check boiler rating plate to determine which
fuel the boiler is set for. Crest boilers CAN
NOT be field converted. Failure to comply
could result in severe personal injury, death,
or substantial property damage.
WARNING
Check boiler rating plate to determine
which fuel the boiler is set for. Crest
boilers CANNOT be field converted.
Failure to comply could result in severe
personal injury, death, or substantial
property damage.
Natural gas:
Pipe sizing for natural gas
1. Refer to Table 6B for pipe length and diameter. Based on
rated boiler input (divide by 1,000 to obtain cubic feet per
hour).
a.
Table 6B is only for natural gas with specific gravity
0.60, with a pressure drop through the gas
piping of 0.3 inches w.c.
b. For additional gas pipe sizing information, refer to
the National Fuel Gas Code, NFPA 54 / ANSI Z223.1
- latest edition, or in Canada CSA B149.1 Installation
Code.
Natural gas supply pressure requirements
1. Target a supply pressure of 7 inches w.c. (1.7 kPa)
measured when the boiler is operating at minimum input
rate. Gas pressure can be adjusted higher or lower than 7
inches w.c. as needed.
2. Pressure required at the gas valve inlet pressure port:
• Maximum 14 inches w.c. (3.5 kPa) with boiler operating.
• Minimum 4 inches w.c. (.99 kPa) with boiler operating.
Figure 6-3 Gas Supply Piping to Regulator
GAS PRESSURE
REGULATOR
(FIELD SUPPLIED)
10'
MINIMUM
*MANUAL SHUT
OFF VALVE
(FIELD SUPPLIED)
*IN COMPLIANCE WITH
248 CMR7.04(9)(f), PROVISIONS
SHALL BE MADE SO THE GAS
SUPPLY TO THE BOILER(S) MAY
BE SHUT OFF FROM A LOCATION
OUTSIDE THE BOILER ROOM.
IMG01040
