Measuring Gas Lines, for Pool Builders
Pool builders know that a properly sized gas line is essential for pool heaters and fire features to function efficiently. If a gas line is too small it will starve the heater, leading to poor performance and costly rework. To help pool builders accurately budget for gas line installations, we’ve created this guide on measuring gas lines correctly.
Why Gas Line Sizing Matters
Incorrect gas line sizing can lead to:
Insufficient gas flow, reducing pool heater efficiency
Increased installation costs if rework is needed
Failed inspections due to non-compliance with local codes
Customer complaints about underperforming equipment
By taking proper measurements and considering key factors upfront, you can avoid these issues and streamline the budgeting process.
Step-by-Step Guide to Measuring a Gas Line for Pool Heaters
1. Identify the Gas Meter or Source Location
Start by determining where the gas meter is located on the property. This is where the gas line will likely originate. Alternatively, if there’s sufficient gas pressure, a line can start from s stub out located elsewhere. If the property does not have an existing gas service, coordinate with the local utility provider to determine meter placement.
2. Determine the Termination Point
Next, identify the location where the gas line will terminate. For most pool builders, this will be at the pool heater, a fire feature or a combination of gas appliances (fire pit, fire bowl, outdoor kitchen, tiki torch, etc.). If multiple appliances will be connected, note each termination point.
3. Measure the Total Distance
Using a measuring wheel or tape measure, determine the total length of the gas line run. Be sure to account for:
Straight-line distance from the meter to the termination point
Any vertical rises (e.g., up and over structures)
PRO TIP: include 5’ vertical feet at each starting point (meter, stub, etc.) and termination point (pool heater, fire bowl, etc.) in your budget
Additional length for routing around obstacles like patios or landscaping
If measuring a line that will run on a wall, it will have to navigate away from windows, doors and ~48” away from electric panels
If measuring for a trenched line be mindful of anything on top of the soil along your path (landscaping, landscaping rocks, roots, etc.) as obstacles will increase time and cost of labor
4. Count the Number of Fittings and Bends
Gas lines experience pressure loss at each fitting and bend. Take note of:
90-degree elbows
T-fittings
Unions or shutoff valves (each fitting adds resistance to gas flow, which affects pipe sizing)
5. Determine the Total BTU Load
Each gas appliance has a BTU (British Thermal Unit) rating, which indicates how much gas it consumes. Common pool equipment BTU ratings include:
Pool heaters: 200,000–400,000 BTU
Fire bowls & fire pits: 60,000–150,000 BTU per feature
Outdoor kitchens: 50,000–100,000 BTU
Add up the total BTU demand for all gas-powered features to determine the required gas flow.
6. Factor in the Gas Pressure
Gas pressure at the meter determines how much gas can flow through a given pipe size. Standard residential gas meters typically supply 7 inches of water column (WC) pressure (low-pressure system), but some properties have 2 psi gas systems (high-pressure). Knowing the pressure helps in selecting the correct pipe size.
7. Choose the Correct Pipe Size
Once you have the total BTU load, pressure, and pipe distance, refer to a gas pipe sizing chart to determine the correct pipe diameter. Common pipe materials include:
Yellow Polyethylene (PE): Ideal for underground installations
Black Iron: Common for above-ground installations
CSST (Corrugated Stainless-Steel Tubing): Flexible and easy to install
Example Calculation
Let’s say you’re running a gas line from a meter to a pool heater 100 feet away (including vertical footage), and the heater requires 400,000 BTU. Assuming 7” WC gas pressure and natural gas, you would typically need at least a 1-1/4” polyethylene pipe to deliver sufficient gas flow.
Pro Tips for Pool Builders
✅ Plan Gas Routing Early: Coordinate with plumbers before finalizing pool layouts.
✅ Account for Future Expansion: Consider running a slightly larger pipe if the homeowner may add more gas appliances later.
✅ Verify Gas Pressure Before Installation: Avoid surprises by checking the gas meter specifications early in the project.
✅ Use a Professional Gas Installer: Proper installation ensures compliance with local codes and safety standards.
Pool Builder Gas Line Planning Checklist
✅ Identify gas source location and confirm gas service availability
✅ Determine all gas-powered features and their BTU ratings
✅ Measure total gas line distance, including vertical and horizontal runs
✅ Count the number of fittings and bends in the planned gas line route
✅ Verify gas pressure at the meter (7” WC or 2 psi system)
✅ Choose the correct pipe size based on length, BTU load, and pressure
✅ Plan for potential future gas appliance installations
✅ Ensure gas line routing avoids unnecessary obstacles to minimize cost
✅ Coordinate with a professional plumber for proper installation and permitting
✅ Check municipal gas code requirements and pass inspection on the first attempt
Need help measuring a gas line for your next pool project?
Contact Wildflower Plumbing & Gas at (512) 292-1966 or email info@wildflowerplumbing.com for expert advice!