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SOLAR HEATING SYSTEM CONSTRUCTION LOG
PROGRESS
REPORT:
September
21, 2002: Added 2 more solar collectors
This
week I built a structure for 2 additional 4 X 8 ft.
SunEarth
Empire
series solar collectors. These are identical to the
original
2 units except that the absorber plates are coated
with
black chrome rather than black paint which has
much
lower emssivity - 12% vs 56%. See their detailed
spec.
sheet for the details. (235K
pdf file)
So
now I have more than doubled my solar heating capacity.
I
did leave the system running through the summer with the
Dow
Frost HD propylene glycol (50% solution) in the collectors.
The
highest temperature that I observed was 245F, which
is
not hot enough to worry about degrading the glycol.
I'm
told that anything over 325F is cause for concern.
Perhaps
with the additional panels I will have to
drain
and flush the system next summer.
In
the process of installing the new collectors, I drained and
stored
the antifreeze mixture, then flushed out the plumbing
with
fresh water until it ran clear. This seems like prudent
maintenance
to clear out old deposits etc. The antifreeze
mixture
looks to be in good shape, the typical Gatorade
green
and clear, not murky. For now I am leaving plain
water
in the collectors, until the weather turns cold.
I
made a few other minor system corrections. I had
originally
placed an automatic air vent at the top of the
collectors
outside. I was warned that these units aren't
rated
for the weather extremes, so I moved inside to just
above
the water storage tank in the floor loop. Then I
installed
a coin type air vent in the "T" to the new collectors:
before
after
Here
is the inside air vent - before and after moving the
automatic
air vent inside and putting the original coin
vent
outside:
before
after
Removing
air from the system is essential to maintain good
fluid
flow through the system. When I fill the system,
I
am extra cautious to purge all air by circulating the
fluid
at high pressure (with either a pump, or house
water
pressure of 30psi) to push all the air bubbles through.
Then
after the system has settled and run for a day or so
I
bleed air from the top vents where air may
have
become trapped.