daestrom wrote:

Flat spiral == 7 feet diameter, 2 feet high...

... 4" high, fool.


Well, if by 'spiral' you mean some sort of serpentine.

A mere disk, only 1 layer tall.

Since the pipe is nominally 4", to get a spiral (even a 'flat spiral'),
you need at least 8" where one turn crosses over the other ;-)

.... with no crossings.

7' diameter coils for 100' total length is only about 4.5 turns. Spread out
in a flat spiral, that would be 7' wide and about 16' feet long. Still a
fair piece of real-estate.

I think we have some posting delay, and you musta missed this posting:

Article 111798 of alt.energy.homepower:
From:
Newsgroups: alt.home.repair,alt.solar.thermal,alt.energy.homep ower,
misc.consumers.frugal-living
Subject: GFX vs home brew
Date: 15 Apr 2006 15:46:00 -0400
Organization: Villanova University

daestrom wrote:

... who has space for 100' of 4" pipe (vertical, coiled or otherwise).[?]

The 4" tall spiral hung under a basement ceiling would be about 7'
in diameter. The 6' tall coil would occupy a 2.7' floor circle.
It seems simpler to install and might have better stratification.

10 PI=4*ATN(1)
20 D=4.25'pipe OD (inches)
30 L=100'pipe length (feet)
40 DI=2'coil ID (feet)
50 DO=DI+2*D/12'coil OD (feet)
60 CI=PI*DI'inner circumference (feet)
70 NT=L/CI'number of turns
80 H=NT*D/12'coil height (feet)
90 PRINT D,DI,DO,NT,H

4.25 2 2.708333 15.91549 5.636738

10 PI=4*ATN(1)
20 D=4.25'pipe OD (inches)
30 L=100'pipe length (feet)
40 A=D*L/12'pipe area (ft^2)
50 DI=2'flat spiral ID (feet)
60 DO=2*SQR(A/PI+(DI/2)^2)'spiral OD (feet)
70 NT=12*(DO-DI)/2/D'number of turns
80 PRINT D,DI,DO,NT

4.25 2 7.006704 7.068288

Nick