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Greenhouse passive heater - Greenhouse pond layout.doc (0/1)

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Posted by 33a6pa001 on May 2, 2004, 7:54 pm
 
I am building a small greenhouse (gh).  I want to include a passive
heating system for those cold winter nights.  My idea is to line the
back wall of the gh (facing south) with 4 inch black ABS pipe filled
with water.  Obviously, I want the tubes of water to collect heat
during the day and release it at night to warm the greenhouse.  The
back wall of the gh will be insulated from the north winds while the
south wall will be windows -- the roof will be glazed with corrugated
polycarbonate panels.  The location gets full sun in winter -- some
shade in the summer -- which seems ideal.

The other wrinkle in this is that I have a pond (approximately 8x10)
which extends about two feet (2x10) into the greenhouse.  I've
attached a site plan of the greenhouse/pond which I hope helps clarify
my description.  (The drawing is NOT to scale.)

My questions:

1.  Does my passive solar heater make sense?  Will it be worth the
bother?

2.  If I stand the pipes on end filled with H2O and the ends capped,
how much airspace should be left in the pipes for the H2O to expand --
or will the H2O get hot enough to expand?

3.  Given that I am located in Jackson, MS and rarely get hard freezes
and that even if we do get a hard freeze it  is usually accompanied by
clear skies (ergo, a full day of full sun before the freeze), how much
should I worry about the pipes freezing?

4.  What effect will the pond have on the greenhouse -- or vice versa?
The front wall of the gh will go across the length of the pond and
extending below the water surface though not to the bottom of the
pond.  The pond water will continually circulate through filters and
the waterfall.

5.  Any other comments or recommendations would be welcome.

Thanks,


Posted by 33a6pa001 on May 5, 2004, 5:41 am
 
Can anyone recommend a web-based forum where I might be able to get
help with this:

I am building a small greenhouse (gh).  I want to include a passive
heating system for those cold winter nights.  My idea is to line the
back wall of the gh (facing south) with 4 inch black ABS pipe filled
with water.  Obviously, I want the tubes of water to collect heat
during the day and release it at night to warm the greenhouse.  The
back wall of the gh will be insulated from the north winds while the
south wall will be windows -- the roof will be glazed with corrugated
polycarbonate panels.  The location gets full sun in winter -- some
shade in the summer -- which seems ideal.

The other wrinkle in this is that I have a pond (approximately 8x10)
which extends about two feet (2x10) into the greenhouse.  I've
attached a site plan of the greenhouse/pond which I hope helps clarify
my description.  (The drawing is NOT to scale.)

My questions:

1.  Does my passive solar heater make sense?  Will it be worth the
bother?

2.  If I stand the pipes on end filled with H2O and the ends capped,
how much airspace should be left in the pipes for the H2O to expand --
or will the H2O get hot enough to expand?

3.  Given that I am located in Jackson, MS and rarely get hard freezes
and that even if we do get a hard freeze it  is usually accompanied by
clear skies (ergo, a full day of full sun before the freeze), how much
should I worry about the pipes freezing?

4.  What effect will the pond have on the greenhouse -- or vice versa?
The front wall of the gh will go across the length of the pond and
extending below the water surface though not to the bottom of the
pond.  The pond water will continually circulate through filters and
the waterfall.

5.  Any other comments or recommendations would be welcome.

Thanks,


Posted by 33a6pa001 on May 7, 2004, 2:12 pm
 Bump

On Wed, 05 May 2004 05:41:32 GMT, 33a6pa001@sneakemail.com wrote:

Can anyone recommend a web-based forum where I might be able to get
help with this:

I am building a small greenhouse (gh).  I want to include a passive
heating system for those cold winter nights.  My idea is to line the
back wall of the gh (facing south) with 4 inch black ABS pipe filled
with water.  Obviously, I want the tubes of water to collect heat
during the day and release it at night to warm the greenhouse.  The
back wall of the gh will be insulated from the north winds while the
south wall will be windows -- the roof will be glazed with corrugated
polycarbonate panels.  The location gets full sun in winter -- some
shade in the summer -- which seems ideal.

The other wrinkle in this is that I have a pond (approximately 8x10)
which extends about two feet (2x10) into the greenhouse.  I've
attached a site plan of the greenhouse/pond which I hope helps clarify
my description.  (The drawing is NOT to scale.)

My questions:

1.  Does my passive solar heater make sense?  Will it be worth the
bother?

2.  If I stand the pipes on end filled with H2O and the ends capped,
how much airspace should be left in the pipes for the H2O to expand --
or will the H2O get hot enough to expand?

3.  Given that I am located in Jackson, MS and rarely get hard freezes
and that even if we do get a hard freeze it  is usually accompanied by
clear skies (ergo, a full day of full sun before the freeze), how much
should I worry about the pipes freezing?

4.  What effect will the pond have on the greenhouse -- or vice versa?
The front wall of the gh will go across the length of the pond and
extending below the water surface though not to the bottom of the
pond.  The pond water will continually circulate through filters and
the waterfall.

5.  Any other comments or recommendations would be welcome.

Thanks,


Posted by nicksanspam on May 12, 2004, 8:03 pm
 33a6pa001@sneakemail.com wrote:
 

What are the dimensions of your gh?


I guess you just want to keep the plants from freezing.


Roger Williams used to have a 200' tomato gh like this in New Brunswick.
His pipes were long and thin and black and horizontal. He says the plants
liked being watered with warmer water in wintertime. I put 200 55 gallon
water drums into one 100' PA gh. It never freezes.


I don't see it. I don't think USENET does attachments.


It sorta makes sense. It seems to me there are better ways. How about dark
plastic vertical 55 gallon drums?


You might leave an inch.


Not much. NREL says January is the worst-case month for solar heating, when
830 Btu/ft^2 of sun falls on the ground and 1070 falls on a south wall on
an average 44.1 F day. The average daily min is 32.7. The record low is 2 F.
 

That alone might keep the gh from freezing. You might trickle some pond
water between two layers of glazing on a cold night to avoid freezing.
 

Or fill the space between two layers of plastic film with air during
the day and soap bubble foam at night.

Nick

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Posted by 33a6pa001 on May 12, 2004, 11:42 pm
 Thanks for your feedback.  I'm reposting the pond/gh layout with this
post (in my experience, USENET shows attachments as separate binary
posts -- must have dropped off the server before you saw my post).

The greenhouse is too small to use 55 gallon -- it is only about 8 x
16, 2x10 of which is taken up with the pond.  That is why I thought of
using a large number of small diameter pipe rather than a few large
drums.  Also, by mounting the tubes along the back (north) wall of the
gn behind the planting shelves I expect they will provide both
insulation as well as passive heating spread all along the planting
shelf which I hope will avoid cold spots.  

Thanks again for your response.  I have one other question for you:
Is there a calculation that a layman (such as me) can use to determine
how quickly a heat sink of a given dimension and material will be
depleted.  I guess what I'm really trying to determine is the relative
benefits of using 4 inch versus 6 in pipe or some larger size or
smaller, for that matter.

On 12 May 2004 16:03:45 -0400, nicksanspam@ece.villanova.edu wrote:



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