Fuel Gas Piping and Gas-Fired Appliance Connections
Fuel Gas Piping and Gas-Fired Appliance Connections
New Jersey adopts the National Fuel Gas Code, NFPA 54, as its fuel gas subcode, with NFPA 58 for LP-gas. Questions test sizing, materials, joints, sediment traps, shutoffs, connectors and appliance venting.
Sizing
Add the rated input of every appliance (Btu/h) and convert to volume: natural gas at about 1,000–1,050 Btu/ft³ means 200,000 Btu/h ≈ 190–200 ft³/h. Then use the longest-length method - measure from the meter to the farthest appliance along the actual route - and enter the capacity table at that length and the permitted pressure drop. Sizing by the shortest run underpipes the system and is wrong.
Installation
- Approved materials: steel pipe, wrought iron, copper, CSST, and listed plastic for underground use, each with the joints the code permits.
- Support intervals tighten with small pipe: 1/2 in. every 6 ft, 3/4 and 1 in. every 8 ft, 1¼ in. and larger every 10 ft.
- Provide a shutoff valve in the same room and a sediment trap (drip leg) downstream of the valve at each appliance.
- Appliance connectors are length-limited (commonly 6 ft), cannot pass through walls, floors or ceilings, and cannot be concealed.
- CSST must be bonded to the grounding electrode system.
- Pressure-test with air or inert gas at the required pressure and hold with no drop before gas is turned on.
Venting and combustion air
Category I appliances use a draft hood and vent connector rising to the chimney or vent; horizontal connectors slope upward at 1/4 in. per ft and terminate clear of windows, doors and intakes. Combustion air comes from two openings sized per the code's Btu/h ratios, or from direct-vent equipment.
Worked example. 100,000 Btu/h furnace + 40,000 Btu/h water heater + 65,000 Btu/h range = 205,000 Btu/h; ÷ 1,025 ≈ 200 ft³/h. At a 60 ft longest length, enter the table at 200 ft³/h and 60 ft to pick the size for the allowed pressure drop.
Traps. Sizing on connected load without the longest length; skipping the sediment trap; concealing a flexible connector; venting a condensing appliance with single-wall pipe not listed for positive pressure.