FL Gas Line Sizing & BTU Demand Calculator
NFPA 54 / FPC §409 sizing tables, meter selection, and FL permit requirements. Natural gas & propane.
Appliance BTU Demand Calculator
Check each appliance you have or plan to install and total the BTU/hr; the total determines your gas line and meter sizing. Apply a demand diversity factor (NFPA 54 §6.1): 1.0 worst case / code minimum (all simultaneous), 0.85 standard residential, 0.75 larger home (likely non-simultaneous), 0.65 very large home.
Appliance BTU Reference Chart
| Appliance | Typical BTU/hr | Notes |
|---|---|---|
| Tankless WH — condensing | 150,000–199,000 | Check nameplate |
| Tankless WH — non-condensing | 120,000–150,000 | High demand |
| Storage WH (40 gal) | 32,000–40,000 | FHR affects size |
| Storage WH (50 gal) | 36,000–50,000 | Most common FL |
| Storage WH (75 gal) | 60,000–75,000 | Large household |
| Gas Furnace | 40,000–150,000 | Per nameplate |
| Gas Range (5-burner) | 55,000–65,000 | All burners + oven |
| Gas Cooktop (4-burner) | 36,000–48,000 | No oven |
| Gas Dryer (standard) | 22,000 | DOE standard |
| Gas Dryer (high-cap) | 30,000–35,000 | DG series |
| Generator — 10 kW | 125,000–145,000 | At full load |
| Generator — 16 kW | 175,000–195,000 | Very common FL |
| Generator — 22 kW (Generac) | 245,000–260,000 | Standard Generac |
| Generator — 26 kW | 305,000–330,000 | Full home backup |
| Pool/Spa Heater — 200 MBH | 200,000 | Typical FL pool |
| Pool/Spa Heater — 400 MBH | 400,000 | Large pool/spa |
| Outdoor Grill | 40,000–60,000 | Estimate |
| Gas Fireplace / Logs | 25,000–80,000 | Per insert |
| Gas Boiler / Hydronic | 80,000–175,000 | Per rating |
| Gas Space Heater | 20,000–30,000 | Wall/floor mount |
Gas Pipe Sizing — NFPA 54 / FPC §409
Enter design BTU demand and longest pipe run to get recommended pipe diameter (NFPA 54 Table 402.4(2), Schedule 40 metallic pipe, 0.3 in. WC pressure drop).
Tip: For sizing, add 50% to actual pipe length to account for fittings (elbows, tees, valves) — the "equivalent length" method per NFPA 54 §6.1.2.
Always size up: NFPA 54 requires selecting the pipe size whose capacity equals or exceeds your design demand. When in doubt go one size larger — oversizing gas pipe is safe; undersizing causes pressure drop, appliance starvation, and failed inspections.
NFPA 54 Pipe Capacity Table — Schedule 40 Steel
BTU/hr capacity at 0.3 in. WC pressure drop · Natural gas (1,020 BTU/cu ft)
| Pipe Size | 20 ft | 40 ft | 60 ft | 80 ft | 100 ft | 150 ft | 200 ft |
|---|---|---|---|---|---|---|---|
| 1/2″ | 119,000 | 84,000 | 68,000 | 59,000 | 52,000 | 42,000 | 37,000 |
| 3/4″ | 255,000 | 178,000 | 145,000 | 127,000 | 111,000 | 90,000 | 79,000 |
| 1″ | 476,000 | 332,000 | 273,000 | 238,000 | 209,000 | 168,000 | 146,000 |
| 1-1/4″ | 987,000 | 687,000 | 562,000 | 491,000 | 428,000 | 347,000 | 303,000 |
| 1-1/2″ | 1,482,000 | 1,032,000 | 845,000 | 738,000 | 643,000 | 522,000 | 456,000 |
| 2″ | 2,831,000 | 1,971,000 | 1,613,000 | 1,410,000 | 1,226,000 | 996,000 | 869,000 |
| 2-1/2″ | 4,897,000 | 3,410,000 | 2,791,000 | 2,440,000 | 2,122,000 | 1,724,000 | 1,503,000 |
| 3″ | 9,163,000 | 6,380,000 | 5,222,000 | 4,564,000 | 3,970,000 | 3,226,000 | 2,814,000 |
Propane (LPG): For propane, multiply BTU capacity values by 0.406, or use NFPA 54 Table 402.4(6) specifically for propane.
CSST Capacity Table — Gastite / TracPipe
BTU/hr · Natural gas · 0.5 in. WC pressure drop · Verify with manufacturer tables
| CSST Size | 20 ft | 40 ft | 60 ft | 100 ft | 150 ft |
|---|---|---|---|---|---|
| 3/8″ CSST | 50,000 | 35,000 | 28,000 | 22,000 | 18,000 |
| 1/2″ CSST | 117,000 | 81,000 | 66,000 | 51,000 | 41,000 |
| 3/4″ CSST | 276,000 | 192,000 | 157,000 | 121,000 | 98,000 |
| 1″ CSST | 544,000 | 379,000 | 310,000 | 239,000 | 194,000 |
| 1-1/4″ CSST | 970,000 | 676,000 | 553,000 | 427,000 | 347,000 |
CSST Bonding Required: Florida adopted NFPA 54 2021 edition requiring CSST bonding per §7.13. All CSST must be bonded to the electrical grounding system with a direct bond at each section. Improperly bonded CSST failed in multiple FL lightning incidents. County inspectors check CSST bonding rigorously.
Generator Gas Line Notes
Standby generators are the most common reason FL homeowners need gas line upsizing.
- Dedicated line required: Generac, Kohler, and Briggs & Stratton require a dedicated gas supply line — not shared with other appliances on the same branch. The manufacturer's manual specifies minimum inlet pressure and pipe sizing.
- Size for full-load BTU, not rated kW: A 22 kW Generac draws 250,000–260,000 BTU/hr at full load on natural gas. At 50% load (typical), about 155,000 BTU/hr. Size the gas line for full load per NFPA 54.
- FL permit required: Generator gas hookup requires a mechanical/gas permit in all FL counties. The gas line must be inspected before commissioning. Licensed plumber or master gas contractor required. Typical cost: $250–$600 for permit + inspection.
- Meter capacity check: Adding a generator often bumps total demand past the residential 175 CFH or 250 CFH meter capacity. Contact FPL/TECO/Peoples Gas to verify meter capacity before installation. Meter upgrade is utility-coordinated and may add 2–6 weeks.
- Propane vs. natural gas: In areas without natural gas (much of rural FL), generators run on propane. Propane has 2.5× the BTU density of NG, so propane pipe can be one size smaller for the same CFH demand. Tank sizing: 120–500 gallon residential standby; 250-gallon minimum recommended for 22 kW units.
Gas Meter Sizing Guide
In Florida the local distribution utility (FPL Gas / Peoples Gas, TECO Peoples Gas, or City Gas) owns and sizes the meter. You or your licensed contractor submit a load calc showing total connected appliance BTU demand; the utility determines if a meter upgrade is needed. Upgrades are typically free but require scheduling and may take 2–6 weeks.
Residential Meter Sizing Chart — Natural Gas
| Meter Size | Max Capacity | Max BTU/hr | Typical Use |
|---|---|---|---|
| B-175 (175 CFH) | 175 CFH | 178,500 | WH + range + dryer |
| B-250 (250 CFH) | 250 CFH | 255,000 | Adds small generator or pool heater |
| 425 CFH Diaphragm | 425 CFH | 433,500 | WH + furnace + gen + pool |
| 800 CFH | 800 CFH | 816,000 | Large residential / commercial |
| 1,600 CFH | 1,600 CFH | 1,632,000 | Commercial / industrial |
FL County Permit Requirements — Gas Work
All gas piping work in Florida requires a mechanical/gas permit. Key requirements by major county:
- Palm Beach County: Gas permit required. Licensed plumber or master gas contractor. CSST bonding strict. Hurricane strap required for exterior-mounted meters and generators.
- Broward County: Permit via Broward County Building Division or city (Ft. Lauderdale, Hollywood). ~10-business-day review. CSST bond inspection at rough-in and final.
- Miami-Dade County: Miami-Dade Building Dept. permit required. High Velocity Hurricane Zone (HVHZ) — extra fastening and CSST bonding. iBuild online portal.
- Hillsborough County: Permit via Hillsborough County or Tampa. TECO Peoples Gas. CSST bonding and pressure test required.
- Orange County: Permit via Orange County EPD or Orlando. Duke Energy / TECO gas service.
- Lee / Collier Counties: Lee County Building Dept. or Collier Growth Mgmt. TECO Peoples Gas. Post-Ian: all gas work requires full pressure test with 20-min hold at 3× operating pressure.
- Duval / Jacksonville: Consolidated City of Jacksonville permit. JEA gas service. Generator gas lines must be on a separate branch.
- Pinellas County: Pinellas County Building Dept. or city (Clearwater, St. Pete). TECO Peoples Gas.
FPC §409.1: All gas piping installations must comply with NFPA 54 as adopted by Florida. Unlicensed gas work is a 2nd-degree misdemeanor. Only a licensed plumber (CFC, CPC), certified gas line contractor, or certified underground utility contractor may pull a gas permit in Florida.
Inspection Checklist — What Inspectors Check
- §409.1 Pipe material: black steel, CSST, PE (underground), or copper (LP only)
- §409.2 Pressure test: 1.5× operating pressure, minimum 10 PSI for 15 minutes with no drop
- §409.3 CSST bonding: direct electrical bond to grounding electrode system, #6 AWG minimum
- NFPA 54 §7.8 Shutoff valve within 6 ft of each appliance, readily accessible
- §409.5 Pipe support: black steel every 8 ft horizontal, CSST per manufacturer (every 4 ft typical)
- §409.6 Drip leg (sediment trap) at each appliance connection with quick-connect coupling
- §409.7 Pipe labeled or marked at intervals ≤10 ft in concealed locations
- NFPA 54 §6.1 Load calculation on permit application showing total BTU demand and pipe sizing per table
- FPC §106.1 Licensed contractor on permit — CFC, CPC, or gas line contractor license number
Why Gas Line Sizing Matters in Florida
- Generator surge is Florida's #1 gas line issue: Post-Irma and Ian, generator installations increased 400% in South Florida. Most undersized gas lines are homes that added a 22 kW generator to a 175 CFH meter already running a tankless water heater — the generator starves for gas.
- Tankless water heaters demand 5× more gas than storage: A tankless WH demands 150,000–199,000 BTU/hr when firing vs. 36,000–50,000 BTU/hr for storage. Many FL homes upgraded to tankless without upsizing the gas line, causing long hot-water waits and pressure drops at other appliances.
- Galvanized pipe corrodes in FL humidity: Galvanized steel gas pipe installed before 1985 is internally corroding in most FL homes due to humidity. Rust particles clog appliance valves and reduce pipe ID, shrinking capacity. Full repipe to CSST or black steel recommended for homes over 30 years old.
- CSST lightning strikes are a FL-specific risk: Florida is the lightning capital of the US. Improperly bonded CSST is vulnerable to lightning-induced arc-through — gas fires that start inside walls. Every FL CSST installation must be directly bonded per NFPA 54 §7.13 and FPC §409.