From: John De Armond
Newsgroups: alt.energy.homepower
Subject: Re: solar heater on flat tar roof
Date: Sun, 25 Nov 2007 19:14:24 -0500
Message-ID: <ag3kk3pb9bk5ol9emitdo3trsc2tg7qgd4@4ax.com>

Having lived for the last 10 years with the spawn of the devil known as a flat tar
roof, my advice to you is to not even look at it too strongly, for that'll form a
leak for sure.

You will damage the roof by walking on it, attaching anything to it, causing any heat
buildup or even thinking about it too hard.  yes, the tar odor will bake out and make
you sick.  Tar odor was a constant problem with my building because fresh air intakes
had to be on the roof.  Even pulling in free air, there was the taint of tar,
especially after the monthly leak patching projects.

I had to penetrate that roof in several places for restaurant vent hoods,
refrigeration and the like.  Every single penetration has leaked at some point.  I've
tried every remedy that my roofers and I could come up with.  Nothing is permanent.
The universal advice was "rubber roof", a $3/sq ft option that I could not afford on
a 7,000 sq ft building.

In the strongest terms possible, I suggest forgetting about doing anything to that
roof.

The only way I ever figured out to make use of the tremendous heat buildup on my roof
was to scatter out a couple hundred feet of industrial quality black rubber hose and
use that to heat water for the restaurant.  That worked well, though the hose quickly
melted into the tar and became one with the roof.

John

On Sun, 25 Nov 2007 12:20:09 -0800 (PST), Beatniks <beatniks@sbcglobal.net> wrote:

>I would like to install a solar air heater atop a flat tar roof that
>pitches slightly facing north. I'd thought about using the top of the
>roof as the back of my thermal enclosure by building a "sandbox" type
>of structure and stretching green house plastic across it. Then, blow
>forced air through it. All in all I could make a 20' x 60' structure
>for about $300.
>
>I am worried about 4 things.:
>
>1. Roof damage. I would remove the plastic in the spring, but if I
>missed a few days...
>2. Off odors. Would chemicals etc. bake out of the tar???
>3. Hail, ice, snow damage to the plastic.
>4. The roof tilts slightly to the north (2 degree). Would it be worth
>my while to build a structure that faces south.
>
>Does anybody have experience with solar heaters on tar roofs???
>
>Thanks

From: John De Armond
Newsgroups: alt.energy.homepower
Subject: Re: solar heater on flat tar roof
Date: Tue, 27 Nov 2007 00:42:37 -0500
Message-ID: <7abnk3h8qabicms86dn25aj7ugc7aep4ns@4ax.com>

On Mon, 26 Nov 2007 19:51:38 -0800 (PST), Beatniks <beatniks@sbcglobal.net> wrote:

>Does the black rubber hose still work?

yes, as of a couple years ago when I shut down the restaurant.

>Did you cover it with anything
>to prevent heat loss? Did you use antifreeze? Etc?

No and no.  Warm weather use only.  After the first frost I blew it out with
compressed air and left it unhooked.  No great planning or effort went into it.  Just
an idea that popped into my head while I was simmering in my own juices on that roof
working on equipment.  I had a spool of surplus hose so I just kinda tossed it out
there in a somewhat zig-zag pattern to see what happened.  It worked well enough to
make it worth the effort.

John