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Old 12-21-2024, 08:56 AM
Bill14564 Bill14564 is offline
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Quote:
Originally Posted by retiredguy123 View Post
Pretty close, but I had to do my own calculation.

The actual inside diameter of 3/4-inch Schedule 40 plastic pipe is 0.804 inches.
The radius is 0.804/2 = 0.402 inches.
The area is 0.402 x 0.402 x 3.14 = 0.507 square inches.
The volume for 50 feet of pipe is 50 x 12 x 0.507 = 304.2 cubic inches
The volume in cubic feet is 304.2 x 0.0005787 = 0.176 cubic feet
The volume in gallons is 0.176 x 7.48 = 1.32 gallons

The Federal regulation for shower heads is 2.5 GPM maximum, so it should take about 32 seconds to get hot water to the shower. But you can reduce that time by about half by turning on a sink faucet at the same time as the shower.
Yeah, I didn't look up the actual inside diameter of a schedule 40 plastic tube. If the plastic tubing in the hot water run meets the average I.D. of 0.804" then it turns out my "about 1 gallon" figure missed your actual figure by 22oz (just under three cups).
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