Can I run one half inch gas line to a range? The existing line is three quarter inch 40 ft. run to a T that feeds a FAU and a water heater. Can I feed the range off of the 12 ft. long one-half inch run to the water heater? The new range is a n upscale 30 inch wide model with one super burner on the top.
Use this chart to get the info you need to do it right.
From what you are describing,
40 feet @ 3/4" only carries 171,000 BTU load so you will have to add up EVERYTHING on that line for BTU calculation. Otherwise count on having to upsize that line to 1" and THEN do branch offs. You should be fine with that setup.
You'll starve that stove of gas if you pull from the water heater. GOOD LUCK
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