Talk of The Villages Florida - View Single Post - Recirculating hot water
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Old 12-21-2024, 08:02 AM
retiredguy123 retiredguy123 is offline
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Quote:
Originally Posted by Bill14564 View Post
Approx. 1gal/50ft of 3/4” pipe

My home, horizontal distance from heater to guest bath = 42’. Add vertical distance and it’s close to 50’.

4.5qts to draw warm water to guest bath. I didn’t time it but times will vary with different fixtures.
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.