Installation Guide

HOME-FLEX CSST 19
Sizing Methods and Examples
CFH, which at 70 feet can be supplied by 1¼" black steel pipe with a maximum
capacity of 490 CFH. 1¼" black steel pipe is the correct size for section A2.
• To size section A3, we can reduce the load by another 190 CFH to 210 CFH for the
remaining heater and the water heater. At 70-feet, 1" black steel pipe can supply
a maximum of 240 CFH, which is sucient for the run. 1" black steel pipe is the
correct size.
• To size section A4, the load is reduced to just the 60 CFH of the water heater. At
70-feet, ½" black steel pipe can provide a maximum capacity of 61 CFH. ½" black
steel pipe is the correct size for section A4.
Step 2 Size Section E: The length is the length of the black steel pipe plus the length of the
HOME-FLEX® CSST run = 70 feet, and total load is 60 CFH. Referencing Table 7.1, ¾" CSST
provides a maximum capacity of 76 CFH at 70 feet. ¾" CSST is the correct size for section E.
Note that CSST ows less gas than the same size and length of black steel pipe. Therefore ¾” CSST is needed to ow
the approximate amount of gas that the ½” black steel pipe is supplying.
Step 3 Size Section D: The length is the length of the black steel pipe up to the branch and
the length of the HOME-FLEX® CSST run = A1 + A2 + A3 + D = 60 feet. Load is the load of the
heater, 150 CFH. At 60 feet, 1" inch CSST can provide a maximum capacity of 156 CFH. 1" CSST
is the correct size.
Step 4 Size Section C: The length is 40 feet and total load is 190 CFH. At 40 feet, 1" CSST
provides a maximum of 195 CFH. 1" CSST is the correct size.
Step 5 Size Section B: The length is 20 feet and total load is 200 CFH. At 20 feet, 1" CSST is
required to provide at least 200 CFH, with a maximum capacity of 288 CFH. 1" CSST is the
correct size.