6 Gas connections
WARNING Use two wrenches when tightening gas piping at boiler (FIG.
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.
Figure 6-2 Inlet Pipe with Backup Wrench
USE BACK UP WRENCH TO PREVENT
PIPE FROM ROTATING
NOTICE | Maximum inlet gas pressure must not | |
exceed the value specified. Minimum | ||
| ||
| value listed is for the purposes of input | |
| adjustment. |
Natural gas:
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.
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 inches, with a pressure drop through the gas piping of 0.5 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.
32 
Installation & Operation Manual
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.
| WARNING | Ensure that the high gas pressure regulator |
|
| is at least 10 feet (3 m) upstream of the |
|
| |
|
| appliance. |
Propane Gas: | ||
|
| Check boiler rating plate to determine which |
| WARNING | |
|
| 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.
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. (3.5 kPa) maximum pressure.
2.Pressure required at 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).
WARNING Ensure that the high gas pressure regulator is at least 10 feet (3 m) upstream of the
appliance (FIG.
Figure 6-3 Gas Supply Piping to Regulator
|
|
| 10' |
|
|
|
|
|
|
|
| * GAS PRESSURE | |||
|
|
| MINIMUM |
|
|
|
|
| |||||||
|
|
|
|
|
|
|
| REGULATOR | |||||||
|
|
|
|
|
|
|
|
|
|
|
| (FIELD SUPPLIED) | |||
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
* MANUAL SHUT OFF VALVE (FIELD SUPPLIED)
* REQUIRED FOR INSTALLATION IN THE COMMONWEALTH OF MASSACHUSETTS
