Subject: Re: Insulating underground copper pipe

From: [email-masked] (Nick Pine)
Date: 16 Oct 1996 03:46:22 -0400

Howard Walker <mail.crosslink.net> wrote:

>By necessity, I am forced to mount my 5 panel array approximately 60 feet 
>from my house.

Have you considered moving your house? :-)

>In one of Ted Lucas' books, a fellow in Pa. did that but utilized 12" 
>diameter PVC with spacers to hold the pipe in place and then had insulating 
>foam injected inside.  He claimed an R value of 30.

Hmmm. I wonder how much that cost.

>Well, 12" is prohibitively expensive.  I have priced 10" and for around $250, 
>I can make the run....anyone have some better input to the situation???

You might consider vermiculite, dry earth, packing peanuts or perhaps fine-
grained clay soil, if you can keep it dry, which the warm pipe might do, if
the water table is never above it. You might take a look at the 1993 ASHRAE
HOF, Fig 6 on page 22.13, "Trends of apparent thermal conductivity of moist
soils," which shows most soils approaching 3 Btu-in/h-ft^2-F, below 3% 
moisture. It looks like fine grained clay soil extrapolates to 0 conductivity
at 0% moisture, but there's an odd plateau at 4.5 Btu-in/h-ft^2-F. Maybe
that's conduction, which would flow in any direction, vs the main (upward)
heatflow in moist soil, when moisture below evaporates and recondenses above.

How about lining a trench with 6 mil poly film, putting a foot of soil in it, 
then the pipe, then another foot of soil, and then folding the poly film over
the top? Hmmm. That might make 3/12 Btu/h-ft^2-F, ie R4... Not too hot.

Nick

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From: "Duane C. Johnson" <[email-masked]>
Date: Wed, 16 Oct 1996 07:23:07 -0700

> the top? Hmmm. That might make 3/12 Btu/h-ft^2-F, ie R4... Not too hot.

Hi Nick;

Why not fill the trench and poly film with the vermiculite or packing peanuts.
This will have considerably more R value and still be realy cheap.
You might want to put a cover plate of 2" styrofoam board over the packaged
insulation and then backfill. The foam board is stiffer so you will still be
able to walk over it.

-- 
CUL8ER

Stupid is Forever
Ignorance can be Fixed

Duane C. Johnson
Ziggy
WA0VBE
Red Rock Energy
1825 Florence St.
White Bear Lake, MN, USA 55110-3364
(612)635-5065 w
(612)426-4766 h
[email-masked]
[email-masked]
http://www.geocities.com/SiliconValley/3027/

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From: [email-masked] (Howard Walker)
Date: 16 Oct 1996 05:17:15 GMT

I need to get started fairly soon.....cold weather is on the way here in VA.

Howard