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# how many 3/4'' pipes goes into an 1'' pipe or 1 1/4'' pipe?

#1
11-15-14, 02:21 AM
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how many 3/4'' pipes goes into an 1'' pipe or 1 1/4'' pipe?

how many 3/4'' pipes goes into an 1'' pipe or 1 1/4'' pipe? i know 3/4'' is double capacity of 1/2'' but want to figure out how many 3/4'' pipes goes into an 1'' pipe or 1 1/4'' pipe? i am wandering if tankless water heaters can be paired up for a radiant heat system and a couple of tankless water heaters can be connected to make 1'' pipe? say 2 50,000 btu water heaters paired up to make 100,000 btu for 1'' pipe. is there a chart that shows doubling pipe capacity?

#2
11-15-14, 02:44 AM
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Google: pipe volumn chart here is one of the first one's I found
Water Content in Pipes

#3
11-15-14, 07:03 AM
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That's a good chart; but if a computer isn't right handy, it's good to know the basis on which the chart was built, all using that old formula for the area of a circle - ΠR² or 3.1416 X the Radius X the Radius. So for the pipes you were interested in, the ratios are as follows:

¾" Pipe = ΠR² = 3.1416 X ⅜ X ⅜ = 0.442 Square Inch;

1" Pipe = 3.1416 X ½ X ½ = 0.7854 Square Inch;

1¼" Pipe = 3.1416 X ⅝ X ⅝ = 1.227 Square Inch.

Multiply these Square Inch areas by 12 inches and you get the Cubic Measurements shown in Pug's Chart.

#4
11-15-14, 10:16 AM
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I usually use a general 'rule of thumb' that up to 1-1/4 pipe size, you can use two of the next smaller size into one.

In other words, two 1/2 into one 3/4;

two 3/4 into one 1;

four 1/2 into one 1;

two 1 into one 1-1/4;

four 3/4 into one 1-1/4;

eight 1/2 into one 1-1/4;

etc.

After 1-1/2, the differences get larger... see chart that pugsl posted.

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