It is important to guard against gas valve fouling from contaminants in the gas ways. Such fouling may cause improper operation, fire or explosion. If copper supply lines are used they must be approved for gas service.
When local codes require a main manual shut-off valve outside the boiler jacket, a suitable main manual shut-off valve must be installed in a location complying with those codes.
Before attaching gas line be sure that all gas pipe is clean on inside. To trap any dirt or foreign material in the gas supply line, a drip leg (or sediment trap) must be incorporated in piping. The drip leg must be readily accessible and not subject to freezing conditions. Install in accordance with recommendations of serving gas supplier. Refer to the current edition of the National Fuel Gas Code, ANSI Z223.1/NFPA 54 or the Natural Gas and Propane Installation Code, CAN/CSA B149.1
Size of gas supply piping may be larger than heater connection on installations where a significant run of piping is required.
To prevent damage, care must be taken not to apply too much torque when attaching gas supply pipe to boiler gas inlet. When installing and tightening gas piping use a second wrench to hold the gas valve to keep the valve from turning. To prevent damage to the gas valve do not use pipe wrench on the valve body.
Fittings and unions in gas line must be of metal to metal type. Apply joint compounds (pipe dope) sparingly and only to the male threads of pipe joints. Do not apply compound to the first two threads. Use compounds resistant to the action of liquefied petroleum gases. The boiler and its gas connection must be leak tested before placing the boiler in operation.
GAS SUPPLY LINE SIZING
The gas piping installation must be capable of supplying the maximum probable gas demand without excessive pressure loss. Depending on local practices, the ALLOWABLE PRESSURE LOSS between the gas meter, or service regulator and each appliance is generally 0.3 or 0.5 inches of water column (0.075 or 0.124 kPa).
For single boiler installation, refer to Table 8 and Table 9 to size iron pipe or equivalent gas supply line size to be used with single unit.
For multiple boiler installation or installations of a single boiler with other gas appliances, please refer to Table 10 and Table 11 on Page 20 to size iron pipe or equivalent gas supply line. These tables are taken from the current edition of the National Fuel Gas Code, ANSI Z223.1/NFPA 54 or the Natural Gas and Propane Installation Code, CAN/CSA B149.1.
•Table 10 is based on a pressure drop of 0.5 inches water column (0.124 kPa), and a gas with a specific gravity of
0.60and a heating value of 1,000 BTU/ft3, approximately that of Natural Gas.
•Table 11 is based on a pressure drop of 0.5 inches water column (0.124 kPa), and a gas with a specific gravity of
1.53and a heating value of 2,500 BTU/ft3, approximately that of Propane Gas.
Where it is necessary to use more than the average number of fittings (i.e., elbows, tees and valves in gas supply line) use a pipe larger than specified to compensate for increased pressure drop.
Table 8 and Table 9 shows the maximum equivalent gas pipe length for a single unit installation. It does not take into account other appliances that may be connected to the gas line. For installation of multiple units, or instances where several appliances are connected to the same line, use Table 10 and Table 11 for proper sizing.
Table 8.
SINGLE UNIT INSTALLATION, SUGGESTED GAS PIPE SIZING. MAXIMUM EQUIVALENT PIPE LENGTH (IN FEET).
BTU | 2” | | 2-1/2” | 3” | | | 4” |
Input | Nat | | Pro | Nat | Pro | Nat | | Pro | Nat | | Pro |
920,000 | 70 | | 150 | 175 | ----- | ----- | | ----- | ----- | | ----- |
| | | | | | | | | | | |
1,300,000 | 40 | | 100 | 100 | 200 | ----- | | ----- | ----- | | ----- |
| | | | | | | | | | | |
1,700,000 | 20 | | 60 | 70 | 150 | 200 | | ----- | ----- | | ----- |
| | | | | | | | | | | |
2,000,000 | 20 | | 50 | 50 | 100 | 150 | | ----- | ----- | | ----- |
| | | | | | | | | | | |
2,600,000 | 10 | | 30 | 30 | 70 | 90 | | 200 | ----- | | ----- |
| | | | | | | | | | | |
3,400,000 | ----- | | ----- | 20 | 40 | 50 | | 125 | 200 | | ----- |
| | | | | | | | | | | |
Natural gas 1000 Btu/ft^3, 0.60 specific gravity @ 0.3 in. w.c. pressure drop. Propane gas 2500 Btu/ft^3, 1.50 specific gravity @ 0.3 in. w.c. pressure drop.
Table 9.
SINGLE UNIT INSTALLATION, SUGGESTED GAS PIPE SIZING. MAXIMUM EQUIVALENT PIPE LENGTH (IN FEET).
BTU | 2” | | 2-1/2” | 3” | | | 4” |
Input | Nat | | Pro | Nat | Pro | Nat | | Pro | Nat | | Pro |
920,000 | 125 | | 200 | 200 | ----- | ----- | | ----- | ----- | | ----- |
| | | | | | | | | | | |
1,300,000 | 80 | | 175 | 175 | ----- | ----- | | ----- | ----- | | ----- |
| | | | | | | | | | | |
1,700,000 | 40 | | 100 | 100 | ----- | ----- | | ----- | ----- | | ----- |
| | | | | | | | | | | |
2,000,000 | 30 | | 80 | 80 | 200 | 200 | | ----- | ----- | | ----- |
| | | | | | | | | | | |
2,600,000 | 20 | | 50 | 50 | 125 | 150 | | ----- | ----- | | ----- |
| | | | | | | | | | | |
3,400,000 | 10 | | 30 | 30 | 70 | 90 | | 200 | ----- | | ----- |
| | | | | | | | | | | |
Natural gas 1000 Btu/ft^3, 0.63 specific gravity @ 0.5 in. w.c. pressure drop. Propane gas 2500 Btu/ft^3, 1.50 specific gravity @ 0.5 in. w.c. pressure drop.
CORROSIVE MATERIALS AND CONTAMINATION SOURCES
Products to avoid:
•Spray cans containing chloro/fluorocarbons
•Permanent wave solutions
•Chlorinated waxes/cleaners
•Chlorine-based swimming pool chemicals
•Calcium chloride used for thawing
•Sodium chloride used for water softening
•Refrigerant leaks
•Paint or varnish removers
•Hydrochloric acid/muriatic acid
•Cements and glues
•Antistatic fabric softeners used in clothes dryers
•Chlorine-type bleaches, detergents, and cleaning solvents found in household laundry rooms
•Adhesives used to fasten building products and other similar products
Areas likely to have contaminants:
•Dry cleaning/laundry areas and establishments
•Swimming pools
•Metal fabrication plants
•Beauty shops
•Refrigeration repair shops
•Photo processing plants
