Gas Piping
Contact your local gas service company to ensure that adequate gas service is available and to review applicable installation codes for your area.
Size the main gas line in accordance with Table 8. The figures shown are for straight lengths of pipe at 0.5 in. W.C. pressure drop, which is considered normal for low pressure systems. Note: Fittings such as elbows, tees and line regulators will add to the pipe pressure drop. Also refer to the latest version of the National Fuel Gas Code.
Schedule 40 Steel or Wrought Iron Pipe is the preferred material for the gas line of this water heater. It is imperative to follow the sizing recommendations in the latest version of the National Fuel Gas Code if Corrugated Stainless Steel Tubing (CSST) is used as the gas line for this water heater.
The heater is not intended for operation at higher than 14.0" W.C.- natural gas, (1/2 pound per square inch gage) supply gas pressure. Exposure to higher supply pressure may cause damage to the gas valve which could result in fire or explosion. If overpressure has occurred such as through improper testing of gas lines or emergency malfunction of the supply system, the gas valve must be checked for safe operation. Make sure that the outside vents on the supply regulators and the safety vent valves are protected against blockage. These are parts of the gas supply system, not the heater. Vent blockage may occur during ice storms.
Table 8 - GAS SUPPLY PIPE LENGTHS (IN FEET) Maximum Equivalent Pipe Length - Natural Gas Only
Input rate |
| Schedule 40 Steel or Wrought Iron Pipe |
| ||
(BTU/HR) | 1/2" | 3/4" | 1" | 1 1/4" | 1 1/2" |
120,000 | 20 | 70 | 200 | 200 | 200 |
154,000 | 10 | 40 | 150 | 200 | 200 |
180,000 | - | 30 | 100 | 200 | 200 |
199,000 | - | 30 | 90 | 200 | 200 |
250,000 | - | 20 | 60 | 200 | 200 |
275,000 | - | 10 | 50 | 200 | 200 |
310,000 | - | 10 | 40 | 150 | 200 |
366,000 | - | - | 30 | 100 | 200 |
390,000 | - | - | 20 | 100 | 200 |
Fitting Type* |
| Equivalent length in feet |
| ||
45°Ell | 0.7 | 1.0 | 1.2 | 1.6 | 1.9 |
90°Ell | 1.6 | 2.1 | 2.6 | 3.5 | 4.0 |
Tee | 3.1 | 4.1 | 5.2 | 6.9 | 8.0 |
Natural Gas 0.60 Specific Gravity, 0.50" W.C. Pressure Drop |
| ||||
*Screwed Fittings |
|
|
|
|
|
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 internally tinned and certified for gas service. Before attaching the gas line, be sure that all gas pipe is clean on the inside.
To trap any dirt or foreign material in the gas supply line, a sediment trap must be incorporated in the piping (see Figure 21). The sediment trap must be readily accessible and not subject to freezing conditions. Install in accordance with recommendations of serving gas suppliers. Refer to the latest version of the National Fuel Gas Code.
To prevent damage, care must be taken not to apply too much torque when attaching gas supply pipe to gas valve inlet.
Apply joint compounds (pipe dope) sparingly and only to the male threads of pipe joints. Do not apply compounds to the first two threads. Use compounds resistant to the action of liquefied petroleum gases.
Gas Meter Size – Natural Gases Only
Be sure the gas meter has sufficient capacity to supply the full rated gas input of the water heater as well as the requirements of all other gas fired equipment supplied by the meter. If gas meter is too small, ask the gas company to install a larger meter having adequate capacity.
Supply Gas Regulator
The minimum gas supply pressure must not be less than 3.5" w.c. (0.87 kPa).
Do not subject the gas valve to inlet gas pressures of more than 14.0” W.C. (3.48 kPa). A supply gas regulator is necessary if higher gas pressures are encountered. See Gas Pressure Requirements and Supply Gas Regulator sections on page 12.
1.Supply gas regulators must be rated above the input Btu/hr rating of the water heater they supply.
2.Supply gas regulators shall have inlet and outlet connections not less than the minimum supply gas line size for the water heater they supply. See Table 8. on page 23.
GAS PIPING AND SEDIMENT TRAP INSTALLATION
Figure 21.
Gas Line Leak Testing
Fire and Explosion Hazard
Use joint compound or Teflon tape compatible with propane gas.
Leak test before placing the water heater in operation.
Disconnect gas piping and main gas shutoff valve before leak testing.
Install sediment trap in accordance with NFPA 54.
Any time work is done on the gas supply system perform a leak test to avoid the possibility of fire or explosion.
1.For test pressures exceeding 1/2 psi (3.45 kPa) disconnect the water heater and its Main Gas Shutoff Valve from the gas supply piping system during testing, see Figure 21. The gas supply line must be capped when disconnected from the water heater.
2.For test pressures of 1/2 psi (3.45 kpa) or less, the appliance need not be disconnected, but must be isolated from the supply gas line by closing the Main Gas Shutoff Valve during testing.
3.Coat all supply gas line joints and connections upstream of the water heater with a
4.Repair any leaks before placing the water heater in operation.
Purging
Gas line purging is required with new piping or systems in which air has entered.
Purging should be performed per the current edition of NFPA 54 the National Fuel Gas Code.
23
