Properly sizing Corrugated Stainless Steel Tubing (CSST) is critical for the safety and performance of your gas appliance system. This calculator helps you determine the appropriate CSST pipe size based on your system's total BTU load, the length of the pipe run, and the type of gas used. Undersizing a pipe can lead to poor appliance performance, while significant oversizing increases material costs.
Natural Gas
Propane (LP)
How to Use the Calculator
Follow these steps to get an accurate pipe size estimation:
Total Appliance Load (BTU/hr): Sum the BTU/hr ratings of all gas appliances that will be supplied by the pipe run. You can find this rating on the appliance's nameplate. For example, a furnace might be 100,000 BTU/hr and a water heater 40,000 BTU/hr, for a total of 140,000 BTU/hr.
Longest Pipe Run (feet): Measure the distance from the gas meter or regulator to the furthest appliance on the line. Use this longest length, not the total length of all pipe sections.
Gas Type: Select whether your system uses Natural Gas or Propane (LP), as their energy densities require different sizing calculations.
Example Calculation
Let's say you are installing a new gas line for a home with the following appliances:
Furnace: 90,000 BTU/hr
Water Heater: 45,000 BTU/hr
Gas Range: 60,000 BTU/hr
The Total BTU Load is 90,000 + 45,000 + 60,000 = 195,000 BTU/hr.
The distance from the meter to the furthest appliance (the gas range) is 75 feet. The system uses Natural Gas.
By entering these values into the calculator (195000 BTU, 75 feet, Natural Gas), the result will show that a CSST-1″ (EHD 23) pipe is required, as it can handle up to 291 KBTU/hr at an 80-foot run, which is the next sizing increment above 75 feet.
Understanding CSST Sizing Factors
CSST sizing tables are designed to ensure that the pressure drop along the pipe does not exceed a certain limit (typically 0.5 inches of Water Column for low-pressure systems). This ensures that even the furthest appliance receives enough gas pressure to operate safely and efficiently.
BTU Load: Higher demand requires a larger pipe diameter to deliver the necessary volume of gas.
Pipe Length: The longer the pipe, the more friction the gas encounters, leading to a greater pressure drop. Longer runs require larger pipes to compensate.
Gas Type: Propane is denser than natural gas and contains more energy per cubic foot. Therefore, a smaller pipe can often be used for propane compared to natural gas for the same BTU load.
Disclaimer: This calculator provides an estimation based on standard low-pressure (under 2 PSI) systems and simplified sizing charts. It is for informational purposes only and does not replace the need for professional design and installation. Always consult the specific CSST manufacturer's installation manual, adhere to all local plumbing and gas codes, and have work performed by a qualified and certified professional. The calculator does not account for pressure drops from fittings, which must be considered in a final design.
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"Required CSST Pipe Size:" +
"" + requiredPipeSize + "" +
"Based on a total load of " + btuLoad.toLocaleString() + " BTU/hr, a " + pipeLength + " ft run, and " + (gasType === 'naturalGas' ? 'Natural Gas' : 'Propane (LP)') + ".";
} else {
resultDiv.innerHTML = "The required load of " + btuLoad.toLocaleString() + " BTU/hr for a " + pipeLength + " ft run exceeds the capacity of the sizes in this calculator. Please consult the full manufacturer's sizing charts for larger pipe sizes or consider a high-pressure (e.g., 2 PSI) system design.";
}
}