How to Size a Gas Line: Complete Guide with Calculator
Learn how to properly size gas lines for appliances. Step-by-step guide with gas line sizing calculator, NFPA 54 standards, and safety requirements.
Step-by-Step Guide
1. Calculate Total BTU Load
Add up the BTU requirements of all appliances on the gas line. Common appliances: water heater (40,000-75,000 BTU), furnace (60,000-150,000 BTU), range (65,000 BTU), dryer (22,000 BTU).
2. Determine Gas Type
Identify if using natural gas (1,000 BTU/cf) or propane (2,500 BTU/cf). Propane requires smaller pipes due to higher energy content per cubic foot.
3. Measure Pipe Length
Measure the total length of the gas line from the meter/regulator to the farthest appliance. Include all horizontal and vertical runs, plus 50% for fittings.
4. Use NFPA 54 Tables
Reference NFPA 54 capacity tables based on pipe size, length, and pressure drop. Standard residential pressure is 7" WC inlet with 0.5" WC maximum pressure drop.
5. Select Pipe Size
Choose pipe size that meets or exceeds total BTU requirement. Common sizes: 1/2" for short runs to single appliance, 3/4" for medium runs, 1" for long runs or multiple appliances.
Frequently Asked Questions
Code Compliance
Gas line sizing must comply with NFPA 54 (National Fuel Gas Code) or local codes. All installations require permits and inspection. Only licensed professionals should install gas lines.