An A-frame solar water heater concept

[Nick Pine]

. ----
. .
. . 30 F
. .
. .
. pond .
.-----------. ----
12' . s 4' . 12' 10.4'
. s .
<--S . s T .
. s . 6.92'
. s .
. s .
. s .
.duct duct.
----------------------------------------------------------------------
12'

We might build a 12'x16' equilateral A-frame with a 4'x12' shallow pond
at the top (view above, in a fixed font) and 2 poly film water ducts
along the north and south edges to avoid wind sliding and overturning...
20 psf makes 208 lb and 1082 ft-lb on each 1' EW slice of the greenhouse,
so we need 12W = 1082 ie W = 90 pounds of water in each foot of duct, eg
1.44 ft^3 of water in a 16" duct.

We could make each of the 10 slightly curved "half-bows" on 4' centers
with 2 12' 1x3s with 1x3 spacer blocks every 2' and a hinge at the top,
and use 3 horizontal 1x3 purlins.

The south side could have 80% shadecloth to make hot air rise under the
pond (which could be poly film over EPDM over foil over welded-wire fence.)

If we can somehow arrange that most of the greenhouse stays cooler while
the airpath between the shadecloth and glazing and under the pond is temp
T during the day, and the space above the pond is also temp T, we might
figure 0.9xsqrt(1000^2+620^2)12' = 12,712 Btu enters a 4' slice of south
glazing on an average 30 F Jan day in Phila, and 0.81^2x4x1177 = 3813 of
that enters the pond. At 130 F, it might also gain 6h(T-130)4ft^2x1.5
= 36T-4680 Btu/day from the bottom, and more, if the ground to the south
is reflective.

If the glazing loses 6h(T-30)12ft^2/R0.8 = 90T-2700 Btu/day and the daily
energy that flows into the slice equals the energy that flows out, 12712
= 3813+(36T-4680) + 90T-2700, so T = 129 F, and the pond slice gains about
3813 Btu, and 50K/3813 = 13.1', so a 16' greenhouse might provide most of
the heat in January. With about 3813x16'/6h = 10.2K Btu/h during solar
collection, 5 gpm (2400 Btu/h-F) would rise 4 F, and 400'x1/2" PE pipe
with 75 ft^2 of U30 surface would rise 10.2K/(75x30) = 5 F.

A row house with a flat roof might have a $98 12' diameter x 3' tall
EZ-Set pool in the basement with a $60 300'x1" fresh water pressurized
PE pipe heat exchanger near the top of the pool under floating Styrofoam
and a low-head pump with a $40 400'x1/2" PE pipe heat exchanger in the
pool bottom. With lots of insulation and 0.8xPi(11/2)^2x3x62.33 = 14216
pounds of water at 110 F after 5 cloudy days, after supplying 5x50K Btu,
it needs to be 110+250K/14216 = 128 F on an average day. Then again, it
might melt It might need reinforcing, eg a tarp tied up around it.
Or maybe we need a different kind of pool.

This might also be a standalone structure in a yard, with the filter pump
that comes with the pool.

Nick

 

[George Ghio]

. ----
. .
. . 30 F
. .
. .
. pond .
.-----------. ----
12' . s 4' . 12' 10.4'
. s .
<--S . s T .
. s . 6.92'
. s .
. s .
. s .
.duct duct.
----------------------------------------------------------------------
12'

We might build a 12'x16' equilateral A-frame with a 4'x12' shallow pond
at the top (view above, in a fixed font) and 2 poly film water ducts
along the north and south edges to avoid wind sliding and overturning...
20 psf makes 208 lb and 1082 ft-lb on each 1' EW slice of the greenhouse,
so we need 12W = 1082 ie W = 90 pounds of water in each foot of duct, eg
1.44 ft^3 of water in a 16" duct.

We could make each of the 10 slightly curved "half-bows" on 4' centers
with 2 12' 1x3s with 1x3 spacer blocks every 2' and a hinge at the top,
and use 3 horizontal 1x3 purlins.

The south side could have 80% shadecloth to make hot air rise under the
pond (which could be poly film over EPDM over foil over welded-wire fence.)

If we can somehow arrange that most of the greenhouse stays cooler while
the airpath between the shadecloth and glazing and under the pond is temp
T during the day, and the space above the pond is also temp T, we might
figure 0.9xsqrt(1000^2+620^2)12' = 12,712 Btu enters a 4' slice of south
glazing on an average 30 F Jan day in Phila, and 0.81^2x4x1177 = 3813 of
that enters the pond. At 130 F, it might also gain 6h(T-130)4ft^2x1.5
= 36T-4680 Btu/day from the bottom, and more, if the ground to the south
is reflective.

If the glazing loses 6h(T-30)12ft^2/R0.8 = 90T-2700 Btu/day and the daily
energy that flows into the slice equals the energy that flows out, 12712
= 3813+(36T-4680) + 90T-2700, so T = 129 F, and the pond slice gains about
3813 Btu, and 50K/3813 = 13.1', so a 16' greenhouse might provide most of
the heat in January. With about 3813x16'/6h = 10.2K Btu/h during solar
collection, 5 gpm (2400 Btu/h-F) would rise 4 F, and 400'x1/2" PE pipe
with 75 ft^2 of U30 surface would rise 10.2K/(75x30) = 5 F.

A row house with a flat roof might have a $98 12' diameter x 3' tall
EZ-Set pool in the basement with a $60 300'x1" fresh water pressurized
PE pipe heat exchanger near the top of the pool under floating Styrofoam
and a low-head pump with a $40 400'x1/2" PE pipe heat exchanger in the
pool bottom. With lots of insulation and 0.8xPi(11/2)^2x3x62.33 = 14216
pounds of water at 110 F after 5 cloudy days, after supplying 5x50K Btu,
it needs to be 110+250K/14216 = 128 F on an average day. Then again, it
might melt It might need reinforcing, eg a tarp tied up around it.
Or maybe we need a different kind of pool.

This might also be a standalone structure in a yard, with the filter pump
that comes with the pool.

Nick

You used the word "Might" 8 times, "Could" 3 times, "If" 3 times, with a
"Maybe" and "Somehow" once each.

"Could" it be that you "Might" be proposing that "If" "Somehow" you
"Maybe" actually built one you could prove your point without using
those words that only confirm that you are in fact just guessing.

 

[News]

You used the word "Might" 8 times, "Could" 3 times, "If" 3 times, with a
"Maybe" and "Somehow" once each.

"Could" it be that you "Might" be proposing that "If" "Somehow" you
"Maybe" actually built one you could prove your point without using
those words that only confirm that you are in fact just guessing.

LOL, that was good. Nothing personal Nick.

 

[[email protected]]

You used the word "Might" 8 times, "Could" 3 times, "If" 3 times, with a
"Maybe" and "Somehow" once each.

Thank you for counting.

"Could" it be that you "Might" be proposing that "If" "Somehow" you
"Maybe" actually built one you could prove your point without using
those words that only confirm that you are in fact just guessing.

The only big risk is the plastic pool losing strength at 130 F, and there
are solutions for that. I go overboard on the "mights" to avoid ignorant
people like you raising angry challenges to 300-year-old settled physics.

Nick

 

[~^Johnny^~]

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Hash: SHA1

Perhaps a scale model would help settle the mights, coulds and
maybes.

Possibly.




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[[email protected]]

EEs abandoned models 20 years ago in favor of simulations, and they don't do
simulations for simple systems. Any sufficiently advanced technology appears
to be magic, and the less you know, the more it seems to be magic. George Ghio
measures risistors in amps, so a large part of the world is magic to him.

Nick

 

[News]

. ----
. .
. . 30 F
. .
. .
. pond .
.-----------. ----
12' . s 4' . 12' 10.4'
. s .
<--S . s T .
. s . 6.92'
. s .
. s .
. s .
.duct duct.
----------------------------------------------------------------------
12'

We might build a 12'x16' equilateral A-frame with a 4'x12' shallow pond
at the top (view above, in a fixed font) and 2 poly film water ducts
along the north and south edges to avoid wind sliding and overturning...
20 psf makes 208 lb and 1082 ft-lb on each 1' EW slice of the greenhouse,
so we need 12W = 1082 ie W = 90 pounds of water in each foot of duct, eg
1.44 ft^3 of water in a 16" duct.

We could make each of the 10 slightly curved "half-bows" on 4' centers
with 2 12' 1x3s with 1x3 spacer blocks every 2' and a hinge at the top,
and use 3 horizontal 1x3 purlins.

The south side could have 80% shadecloth to make hot air rise under the
pond (which could be poly film over EPDM over foil over welded-wire fence.)

If we can somehow arrange that most of the greenhouse stays cooler while
the airpath between the shadecloth and glazing and under the pond is temp
T during the day, and the space above the pond is also temp T, we might
figure 0.9xsqrt(1000^2+620^2)12' = 12,712 Btu enters a 4' slice of south
glazing on an average 30 F Jan day in Phila, and 0.81^2x4x1177 = 3813 of
that enters the pond. At 130 F, it might also gain 6h(T-130)4ft^2x1.5
= 36T-4680 Btu/day from the bottom, and more, if the ground to the south
is reflective.

If the glazing loses 6h(T-30)12ft^2/R0.8 = 90T-2700 Btu/day and the daily
energy that flows into the slice equals the energy that flows out, 12712
= 3813+(36T-4680) + 90T-2700, so T = 129 F, and the pond slice gains about
3813 Btu, and 50K/3813 = 13.1', so a 16' greenhouse might provide most of
the heat in January. With about 3813x16'/6h = 10.2K Btu/h during solar
collection, 5 gpm (2400 Btu/h-F) would rise 4 F, and 400'x1/2" PE pipe
with 75 ft^2 of U30 surface would rise 10.2K/(75x30) = 5 F.

A row house with a flat roof might have a $98 12' diameter x 3' tall
EZ-Set pool in the basement with a $60 300'x1" fresh water pressurized
PE pipe heat exchanger near the top of the pool under floating Styrofoam
and a low-head pump with a $40 400'x1/2" PE pipe heat exchanger in the
pool bottom. With lots of insulation and 0.8xPi(11/2)^2x3x62.33 = 14216
pounds of water at 110 F after 5 cloudy days, after supplying 5x50K Btu,
it needs to be 110+250K/14216 = 128 F on an average day. Then again, it
might melt It might need reinforcing, eg a tarp tied up around it.
Or maybe we need a different kind of pool.

This might also be a standalone structure in a yard, with the filter pump
that comes with the pool.

Nick

I read the first paragraph and there was nothing to tell me what all this
was about, so I stopped reading. What is the function of the A frame? Then
I may read the rest of it.

 

[Ranieri]

Nick

I read the first paragraph and there was nothing to tell me what all this
was about, so I stopped reading. What is the function of the A frame? Then
I may read the rest of it.

SAT: 780 math / 410 verbal

 

[George Ghio]

Thank you for counting.




The only big risk is the plastic pool losing strength at 130 F, and there
are solutions for that. I go overboard on the "mights" to avoid ignorant
people like you raising angry challenges to 300-year-old settled physics.

Nick

Nick,


You want someone else to do the work. I suggest that you do the work.

The words you use indicate that you are just guessing.

I have the greatest faith in your maths and the physics. The questions
are; "Can you prove your theory? Can you in fact build this? Test it?
Prove it? Present the results in plain English?

Ignorance generates words like "Might" "Could" "If" "Maybe" "Somehow".

You have presented a theory riddled with doubts.

It is now time to remove the doubts.

Go for it.

 

[George Ghio]

EEs abandoned models 20 years ago in favor of simulations, and they don't do
simulations for simple systems. Any sufficiently advanced technology appears
to be magic, and the less you know, the more it seems to be magic. George Ghio
measures risistors in amps, so a large part of the world is magic to him.

Nick

There is no magic involved when a Rheostat is clearly rated by the
manufacturer in amps. I did not make the said Rheostat. I did not rate
the Rheostat. I commented on the fact that it was rated in amps as a
point of interest.

Now, can you prove your theory with a working unit or not.

 

[Derek Broughton]

Gotta laugh. Note the concept of putting water near the peak of a
triangular prism to absorb and store heat. This wonderous idea is
presented by the same Nickie that pooh-poohed the idea of
inexpensively preheating water for a domestic water heater via the
simple expedient of placing a 4" pipe underneath and along the
ridgeline of a roof. IIRC, his comments were along the lines of what
if it leaks, what if it freezes? Yet, he has no comment or solution
for the same questions about his own Nickie special design.

And your problem is??? In a stand-alone greenhouse, you don't have a
serious problem if it springs a leak. If it's in your house, you sure do.

 

[[email protected]]

Gotta laugh. Note the concept of putting water near the peak of a
triangular prism to absorb and store heat. This wonderous idea is
presented by the same Nickie that pooh-poohed the idea of
inexpensively preheating water for a domestic water heater via the
simple expedient of placing a 4" pipe underneath and along the
ridgeline of a roof. IIRC, his comments were along the lines of what
if it leaks, what if it freezes? Yet, he has no comment or solution
for the same questions about his own Nickie special design.

Since you ask, I'll comment. The pond above is much more efficient than
a pipe in the attic, and it's a draindown system with no exposed water
to freeze at night.

Nick would have people construct a special A-frame greenhouse instead,
to attempt to capture enough heat to warm an entire house...

Just hot water for showers. The "special greenhouse" might cost $200.

making the cost/benefit ratio of heating water to the same temperature
totally impractical...

What does that mean?

especially on those cold winter days when 90% cloud cover can be common
for weeks at a time.

That might happen north of the Arctic circle

...a more simple alternative to A frame plan "A" might be the less
pretentious plan "b,"

Unpretentious is nice

where a b shape holds a tank or pool at the base (on the ground),
contained within strawbales, and a more or less vertical wall of
inexpensive construction grade 2" x4" lumber forms the staff of the b,

The staff of the b?

partly braced by the tank and strawbales. This structure would be on the
south side of a house, with a vegetable garden just south of the structure.

Vegetable gardens don't reflect much sun...

1 clear plastic
2 clear plastic
3 black shadecloth
4 black plastic
5 insulation and frame
6 winterime tempered herbs cloche
Sun > >
12345
///// I
///// I
///// I
///// IHouse
///// I
///// I
///// plastic pla I
///// straw straw stic p I
// 6/ pool or tank straw l I
// /straw straw straw astic I
garden south // /ground ground ground north house

....6 is the garden? Looks like your ascii art got corrupted.

The southern side of that b wall would be double glazed with plastic,
while the north side of the wall would have black plastic and black
shadecloth over insulation and a simple frame. The wall might even
tilt, like an italic letter b for a better solar angle. Cold water
from the bottom of the tank would be pumped by a low volume pump
(bilge pump?)...

Attwood's $30 pumps have a 3 year guarantee and a 600 hour lifetime.

to the top manifold and allowed to trickle down through the shadecloth
(which would spread and even the flow) and over the black plastic,
underneath the first closely-spaced layer of plastic glazing.

Nice, altho this requires more pump power than a horizontal pond above
a tank with a spiral pipe heat exchanger in the bottom which leaves
the water level of the supply and return pipes just below the pond when
the pump isn't running. What would you use for a pump and a tank, vs
a $98 EZ-set setup?

Since the pump would be controlled by a thermostat or solar sensor
at the top of the b, it would only run when it could accumulate
heat energy, and no water would be exposed to the cooling effects of
night air or have to be drained or pumped without benefit. The heated
water drips into and is allowed to accumulate on the top of the tank,
thus preserving a greater delta T between the pumped water and the
solar collector, increasing efficiency.

Nice. You might turn the pump on with Grainger's $8 2E247 snap-disc
thermostat in a 1 liter soda bottle (closed above 130 F and open below
115) and turn it off with Grainger's $10 2E365 thermostat (closed below
120 and open above 140) sensing the water temp, if you plan to use a
pressurized flat PE pipe spiral as the cold water heat exchanger.

Hot water for the house is taken from the top of the tank, and the
return pipe enters below mid-level in multiple low-flow horizontal
outlets to help preserve the stratification.

You might pressurize the hot water, unless you live in the basement.

The staw bale insulation for the pool or tank could be seeded with
fertilizer or dried manure during the fall in preparation for the
coldest part of the winter. During that period a small amount of
water would be allowed to saturate the inner layer of straw, setting
up an exothermic composting process underneath the pool that would be
buffered by, and add to the heat of, the pool of water during those
cloudy and short days that Nick's design fails to address.

Sounds like work. You mightr say more about this compost process.
I did address the cloudy and short days, using actual numbers

With this design, the weight of the large amount of water safely rests
on straw which is on the ground, without requiring an expensive and
possibly dangerous permanent structure.

Same for the A-frame, with most of the water on the ground.

...The issue of freezing is avoided with the simple expedient of a small
drainback hole in the pipe or hose from the pump to the top of the frame.

Sounds familiar.

When spring arrives, the plastic, shadecloth, and insulaton are
removed from the frame, the hay from the south side of the tank is
spread as compost and mulch, and a layer of clear plastic replaced to
form a low tent along the south side of the tank, for use as a
cloche/greenhouse in starting seedlings for the garden.

"Work!" -- Maynard G. Krebs

This design is superior to Nicks in that it has
1. far lower cost
2. far greater safety
3. far simpler and easier construction
4. year around use compared to seasonal use
5. no problems with freezing
6. secondary heat source for cold cloudy days
7. lower pumping costs per unit of useful heat
8. no structural permits and inspection required
9. less impact from vandalism
10. less environmental impact
11. portability
12. lack of acompanying psuedomath justification

I disagree.

Nick

 

[George Ghio]

Since you ask, I'll comment. The pond above is much more efficient than
a pipe in the attic, and it's a draindown system with no exposed water
to freeze at night.




Just hot water for showers. The "special greenhouse" might cost $200.




What does that mean?




That might happen north of the Arctic circle




Unpretentious is nice




The staff of the b?




Vegetable gardens don't reflect much sun...




...6 is the garden? Looks like your ascii art got corrupted.






Attwood's $30 pumps have a 3 year guarantee and a 600 hour lifetime.




Nice, altho this requires more pump power than a horizontal pond above
a tank with a spiral pipe heat exchanger in the bottom which leaves
the water level of the supply and return pipes just below the pond when
the pump isn't running. What would you use for a pump and a tank, vs
a $98 EZ-set setup?




Nice. You might turn the pump on with Grainger's $8 2E247 snap-disc
thermostat in a 1 liter soda bottle (closed above 130 F and open below
115) and turn it off with Grainger's $10 2E365 thermostat (closed below
120 and open above 140) sensing the water temp, if you plan to use a
pressurized flat PE pipe spiral as the cold water heat exchanger.




You might pressurize the hot water, unless you live in the basement.




Sounds like work. You mightr say more about this compost process.
I did address the cloudy and short days, using actual numbers




Same for the A-frame, with most of the water on the ground.




Sounds familiar.




"Work!" -- Maynard G. Krebs




I disagree.

Nick

The simple solution Nick. Build it. Collect the real data from use.
Compare data to your theory.

 

[Derek Broughton]

Harry Chickpea wrote:

....

It isn't my problem. As I pointed out to Nick at the time, a 4" pipe
contains enough thermal mass, and the location is inherently warmer
than the rest of the attic, to preclude freezing in all but the most
extreme climates, and allowing a small cushion of air at the top for
expansion would resolve the issue even if it did freeze. The pipe
would be no more or less likely to spring a leak than any other pipe.
I suggest that you and Nick might want to remember that people have
plumbing and even <gasp!> bathtubs on the second floors of their
homes, and condos and apartments and office buildings have plumbing
that reaches to the sky. Somehow, they survive.

What do you consider "the most extreme climates"? Most of the US, and
practically all of Canada, are subject to regular conditions _well_ under
freezing, and we do NOT have plumbing along the ridgelines of our roofs.
To prevent ice-damming, attics are kept as cold as possible, and all
plumbing is kept below the insulation. If your attic is warm enough in
winter to prevent a pipe freezing, you're wasting too much energy.

I haven't a clue (and don't really care) if Nick's idea is sound, but his
objection to a 4" pipe under the ridgeline of a roof certainly is.

 

[Cosmopolite]

The simple solution Nick. Build it. Collect the real data from use.
Compare data to your theory.

I agree with this sentiment.

It would be better for everyone if these theoretical projects were
actually built and tested, with all data posted, before someone
invests their time and money for construction and then finds out that
the return on investment is insufficient.

There are times when practice does not fulfill, what theory promises.

 

[Anthony Matonak]

I agree with this sentiment.

It would be better for everyone if these theoretical projects were
actually built and tested, with all data posted, before someone
invests their time and money for construction and then finds out that
the return on investment is insufficient.

There are times when practice does not fulfill, what theory promises.

Well, the design is made public through this forum and it doesn't
look like a demonstration/test version would be either difficult
or expensive to build. Anyone could build it and tell us how it
does or does not perform. It need not be Nick. Certainly, there
must be someone with enough time on their hands to do such a thing.

Anthony

 

[News]

I agree with this sentiment.

It would be better for everyone if these theoretical projects were
actually built and tested, with all data posted, before someone
invests their time and money for construction and then finds out that
the return on investment is insufficient.

There are times when practice does not fulfill, what theory promises.

Nick posted a theory. What is wrong with that? A theory that others may
take up in full or partially, or spark somthing in their mind. Nick is a
thinker and thinks out loud. Nothing wrong with that at all. I like
thinkers.

The problem is he writes like a "who done it". You have to read it all to
find out what it does at the end, just like Agatha Christie.

 

[George Ghio]

Nick posted a theory. What is wrong with that? A theory that others may
take up in full or partially, or spark somthing in their mind. Nick is a
thinker and thinks out loud. Nothing wrong with that at all. I like
thinkers.

The problem is he writes like a "who done it". You have to read it all to
find out what it does at the end, just like Agatha Christie.

Nick is a talker. That's all. He talks and talks and talks. Then expects
someone to build one of his pipe dreams.

If someone does build something Nick proposed and it does not work as
per Nick's projections he can always say "Well I only said "Might"
"Could" "If" "Maybe" "Somehow" so its not my fault it doesn't work. It
was just an idea.

Talk Talk Talk Talk Talk Talk Talk Talk Talk Talk

Just don't let him near any tools or some one could get hurt.

 

[News]

It isn't my problem. As I pointed out to Nick at the time, a 4" pipe
contains enough thermal mass, and the location is inherently warmer
than the rest of the attic, to preclude freezing in all but the most
extreme climates,

Say a 20 foot length of this 4" plastic pipe running under the roof apex in
the attic. Say, 20C in the attic and water inside, coming in from the water
mains at 5C, who long to raise the mass of water to 20C?

How much are you going to gain from solar heat? It may take a while to
payback the cost of the pipe and fitting.

Just out of interest.

 

[John P Bengi]

Yeah, he is full of ideas and also a troll. This means when you object to
one of his fanatical theories he tries to get everybody against you because
he cannot support his theories and doesn't value discussion on it, just the
lime light.