Subject: Looking for Info on Pool Solar Heating in NJ

From: "John W. Moffett" <[email-masked]>
Date: Mon, 09 Sep 1996 01:11:56 -0400

Hello all,

I live in New Jersey with a well shaded pool.  Have nice sunny roof and 
would like to use solar to warm up the pool by 10 degrees.  Local pool 
stores are no help - if it isn't gas fired they don't do it.

I am having trouble finding dealers, installers, and others with 
experience with pool solar heaters.  (Like, one local pool store warned 
that squirrels will eat the panels!  Any truth to that one?)

Any experience with solar in the North East appreciated.

Thanks,
[email-masked]

---

From: [email-masked] (Nick Pine)
Date: 9 Sep 1996 12:11:44 -0400

>Hello all,

Hello John,

>would like to use solar to warm up the pool by 10 degrees.

How about floating two dozen $16 2' x 8' x 2" thick pieces of Styrofoam on the
pool, and putting a layer of 5 cent/ft^2 black polyethylene film on your sunny
roof, and putting another layer of clear film over that, attached with some
75 cent/linear foot aluminum extrusion clamps, and drilling a 1/8" hole every
6" in a 1 1/2" PVC pipe along the ridgeline, to spray some pump filter water
between the two plastic films, which runs down into the gutter and back into
the pool, whenever the sun is shining and the pool is not warm enough?

The weak point in solar pool heating is usually the cover, which is a poor
insulator, compared to a house wall. A 24' x 32' 80 F pool with an outdoor 
temp T might lose 24(80-T)768ft^2/R10 Btu/day through a 2" Styrofoam cover,
and a rooftop with a south-facing area of 20' x 32' might gain 640K Btu/day
of winter sun, and lose (6 hr)(80-T)640ft^2/R1, so if Ein = Eout,

   24(80-T)76.8 = 6(80-T)640, or equivalently,
    4(80-T)76.8 = (80-T)640,  or equivalently,
     (80-T)76.8 = (80-T)160,  or equivalently,
	   76.8 = 160.

Hmmm. What is wrong with this solar arithmetic? Is it true that solar heating
does not work, as many people say?

Aha, I forgot the sun...

   24(80-T)76.8       = 640K - 6(80-T)640,  or equivalently,
     (80-T)76.8       = 26.7K -6(80-T)26.7, or equivalently,
     (80-T)(76.8+160) = 26.7K,              or equivalently,
     (80-T)236.8      = 26.7K,              or equivalently,
      80-T            = 26.7K/236.8,        or equivalently,
      80-T            = 112.8,              or equivalently,
                    T = 80 - 112.8 = - 32.8. 

So, could this pool stay 80 F when the outdoor temp is minus 33 F? Probably
not, since there would be some evaporation of water and heat losses between
the floating panels, and losses to the cool ground around the sides, and 55 F
R10 ground under the bottom, but still... Not bad.

How hot could we make the pool, with this arithmetic? In Philadelphia,
in December, with an average outdoor temperature of 36 F? Tp-36 = 112.8,
so Tp = 112.8 + 36 = 148.8 F. Could we make it a 104 F hot tub?

How much would it cool over a cloudy week? If it were 4' deep, and most of
the heat loss were through its R10 cover, it would hold C = (24x32)x4x64,
about 200,000 pounds of water, with a thermal resistance R = R10/(24x32), so
RC = R10/(24x32)x(24x32)x4x64 = 10x4x64 = 2560 hours or 106 days or 15 weeks.

Over one week, it might cool to 36 + (104-36)exp(-1/15) = 99.7 F.

Nick

---

From: [email-masked] (Andy Burgess)
Date: 12 Sep 1996 12:37:34 -0700

>pool, 

<actual heater idea deleted, good one Nick!>

An idea for insulating pools is to float styrofoam spheres (1-2 inches
in diameter or so, a couple of spheres deep). That way you insulate and can 
still swim without messing with the insulation. I don't know if styrofoam 
popcorn used for packing would work -- might saturate and sink but worth 
experimenting with outside the pool perhaps.

Even air filled plastic balls would help insulate and allow pool use.

Good luck.
-- 
Best regards,
Andy Burgess
[email-masked]

---

From: [email-masked] (Nick Pine)
Date: 12 Sep 1996 22:12:48 -0400

Andy Burgess <[email-masked]> wrote:
>Nick Pine wrotes about:
 
>>...floating 2 dozen $16 2' x 8' x 2" thick pieces of Styrofoam on the pool, 

Oops. That shoulda been 2 dozen $8 2' x 8' x 2" thick pieces of Styrofoam.
Still a lot of stuff to get out of the way when you want to go for a swim.

><actual heater idea deleted, good one Nick!>

Thank you :-)

>still swim without messing with the insulation.

You can? Hmmm. Underwater, maybe.

>I don't know if styrofoam popcorn used for packing would work -- might
>saturate and sink but worth experimenting with outside the pool perhaps.

I think that popcorn is more like beadboard than Styrofoam, 
ie, white, not blue or pink. Oh wait, I've seen pink...
Would a lot of kids probably swallow the popcorn and drown?

>Even air filled plastic balls would help insulate and allow pool use.

One place I worked used ping-pong balls to cover their IC boiling bath.

How about putting the popcorn in a heat-sealed polyethylene film pillow? 

Or filling the pillow with soap bubbles, and squeezing them out through
a filter to break them down into 200 times less liquid by volume when
the pillow is rolled up?

Nick

---

From: [email-masked] (Seamus)
Date: Sun, 15 Sep 1996 15:59:37 GMT

>Even air filled plastic balls would help insulate and allow pool use.
	Yes, I found that it sinks or becomes sticky, saturated, heavy
and obnoxious to handle.(In the pool.)
	Floating bubble plastic from an elevating counterpoised
roller, with balancers to auto spread the sheet on the surface, works
and stops heat loss by evaporation dead. The bubble plastic can be
recycled from commercial sources and NOT joined by sticky tape as it
degrades, but coarsely sewn with a manmade yarn such as agricultural
bale binder twine. This works. Bear in mind that if the pool is not
shaded or indoor, then these materials are UV degradable.
	This cover is manually workable by one ordinary unfit person
in under a minute.

Best regards, Jim

---

From: [email-masked] (Nick Pine)
Date: 3 Oct 1996 13:00:26 -0400

Andrew McKegney <[email-masked]> wrote:
 
>>>>I wonder why most solar heating professionals completely ignore the
>>>>greenhouse industry, who have been working with inexpensive and practical
>>>>outdoor transparent structures for years. And vice versa...

>>Still wondering...
 
>Because solar space heating is a con.

Yes, there's been lots of that. It's time to fix that.

>It may be great for enthusiasts who have more time and money and space and
>a great do-in-yourself streek, but for the average homeowner, it is not
>cost effective or practical.

Agreed, as usually done, with rooftop panels, or direct gain houses
outside of the southwest. But that doesn't mean it has to be that way.

>Very few people have the space to install transparent structures to heat
>their homes. 

Bullshit. Every house has a south or southwest or southeast wall or roof.
Altho some houses are more suitable than others.

>>I felt perfectly comfortable in an 98 F outdoor hotel pool in Banff, Alberta,
>>when the air temp was -12 F, at night, with snow falling on my head... It was
>>too warm for swimming.  

Ice all over the steps and handrails, too...
 
>I bet that pool was not heated by a solar system. Nor could it be
>during the winter. A more likely renewable heat source would be a hot
>spring, which I don't think Banff has.

Can you say "Banff Springs Hotel" :-)

Nick

---

From: Dick Lambert <[email-masked]>
Date: Thu, 03 Oct 1996 18:29:49 -0700

I missed the first posts on this subject but I gather that Andrew
McKegney  was looking for some ideas on solar pool heating in a cold
climate.  Will someone with a 12 year old solar pool heater in Minnesota
do?  Minnesota - you know, the place where summer is two months of bad
skiing.

I put four 1000' coils of 1" black poly piping on my (admittedly flat)
garage roof.  They are plumbed in parallel to keep the head loss low.  A
small Grundfos pump, controlled by a $100 controller that senses
the temperature of the roof as well as the pool water, 
circulates water through the system anytime the roof temperature
exceeds the pool water temp.  It also will run the solar pump if the roof 
temperature is below 40 to prevent freezing.  I use a "bubble pack"
solar cover.  I haven't had any maintenance expenses on the system in 12
years and it typically keeps the pool between 88 and 90 (the pump turns
off at 90) .  It is able to bring the water up about 6 or 7 degrees per
sunny day if we have a long cool cloudy stretch.  In short, the pool has
always been at a comfortable temperature anytime the outside was warm
enough for anyone to be interested in swimming.  We typically open the
pool in late May and close it in early September.

-- 
Richard C. Lambert                      800 Brenner Avenue
President                               Roseville, Mn 55113-1904
R.C. Lambert & Associates, Inc.         (612) 483-1492
Energy Conservation Consulting Engr     [email-masked]

---

From: dale <[email-masked]>
Date: Mon, 07 Oct 1996 08:44:35 +0100

At last someone with real life experience!

I have been trying to do something like this in an area of 
the world where black pipe of any kind does not exist 
(northeast Poland). Whatever I want, I will have to import or 
carry it in from a long ways off, so I want to get it right 
at the start. 
 
What is a grundfos pump? 
How many gallons per minute are going through it?

Who makes the controler? 

What exactly is black poly piping? 'Poly' what? Is it 
flexible, is it resistant to decay from the sunlight and hot 
water? How much total space does a 1000' coil take up. Is it 
coiled tight or with space between the coils? Does it have 
any covering (glazing, glass or plastic) over it, or 
insulation under it? Would that make a significant 
difference?

---

From: dale <[email-masked]>
Date: Mon, 07 Oct 1996 08:45:08 +0100

What is a grundfos pump? 

Who makes the controler? 

[email-masked]

---

From: [email-masked] (Sylvan Butler)
Date: 8 Oct 1996 03:51:13 GMT

>What exactly is black poly piping? 'Poly' what? Is it 

black polyethylene

>flexible,

So-so.  Won't do sharp bends, but does bend somewhat.

>is it resistant to decay from the sunlight and hot 

Sunlight - not impervious, but resistant.  Hot water?  Somewhat.

>water? How much total space does a 1000' coil take up. Is it 

A lot.

sdb

---

From: [email-masked] (Andrew McKegney)
Date: Mon, 07 Oct 1996 16:19:45 GMT

Dear Mr. Lambert

Thankyou for posting your experience. Actually it is a strong
supporting case for the "discussion" I have been having with Mr. Pine.

Your system which uses poly pipe sounds very typical of most
do-it-yourself systems -although larger by a factor of ten - which is
good! Many do-it-yourselfers will only install 100 - 300 feet of pipe
(not 4000 like you) and make the same claims about performance as you.
Unfortunately their systems aren't capable of heating that well.
(thermal physics raises it's practical head.!<)

The only caution I suggest about coils of pipe, is being sure to drain
them completely before freezing weather. Poly pipe is not made to be
exposed to the sun (it's designed to be buried) and as a result it
hardens after 2-3 years, and will split if it is frozen full of water.
On a flat roof it may not be too hard to blow the pipe out. On a
sloped roof, it is very hard to blow the water out of the bottom half
of the loops of coil.

PS. This thread went in this direction because I was recommending the
use of conventional, manufactured, solar pool heating panels.

Andrew McKegney

---

From: [email-masked] (Hardison)
Date: Wed, 09 Oct 1996 05:16:30 GMT

>the temperature of the roof as well as the pool water, 

I have the same set up (3000 FT) of coiled hose on my patio cover.  I
just had a nice swim this evening in 84F water (so it works).  But I
don't have a differential temperature controller like you describe.
I haven't seen any $100 controllers.  Was that years ago?  I need one
of those things!  Please post a source!

S. Hardison>

---

From: [email-masked] (Hardison)
Date: Wed, 09 Oct 1996 05:39:45 GMT

>So-so.  Won't do sharp bends, but does bend somewhat.

Actually, the 0.6 mm black poly drip irrigation hose will almost make
a 1' diameter bend.. good for coiling flat.

>Sunlight - not impervious, but resistant.  Hot water?  Somewhat.

Sunlight?  black drip irrigation hose lasts a long time right out in
the very hot sun.  Over 5 years, I'm sure... from experience.  In
fact, I can't remember ever seeing this stuff anything worse that a
little stiff after 10 years right out in the vey hot California
central valley sun.  Pool chemicals?  Maybe that's a problem.  I don't
know yet.

>A lot.
It isn't the space, it's the square feet of surface exposed to the
sun.  A 500 foot coil donut is about 27 square feet- a 6 foot diameter
donut with a 1 foot diameter hole.  A 1000 foot coil would be a little
over 8 feet in diameter.  I have six 6-foot diameter coils for ease of
handling.  Once a 6 foot dia. coil is hot melt glued every 6 inches or
so around the coil, you can pick it up by the middle and hoist it up
on the roof.

---

From: [email-masked] (Hardison)
Date: Wed, 09 Oct 1996 05:51:27 GMT

>exposed to the sun (it's designed to be buried)

I've used 1/2" black poly irrigation hose in the garden for 10 years
with nothing more serious than a little stiffness. It commonly sees 50
psi and lays in the sun year after year.  I suspect this irrigation
hose will last a lot longer as a solar collector than you're supposing
here.

> and as a result it

This is probably true, but where you don't worry about hard freezes,
like here in the California central valley, a lot of black hose is a
viable solution for home-brew solar pool heating.   

S. Hardison

---

From: [email-masked] (Nick Pine)
Date: 9 Oct 1996 16:07:31 -0400

Talked with Sven Tjernagel, who just got back from a trip. He says pool
chlorine should be no problem with EPDM rubber collectors, altho
roof pitch is, the way he builds them. He suggests no more than a 5:12
roof pitch, for an 8-10 year lifetime under two layers of glass. He imagines
that with no glass, the rubber should last 15 years or more. He sold these
things as a product for 9 years, along with their extrusions and hardware.

His collectors cost $9.30, including two layers of glass, etc, and the
largest ones are about 10' tall by 40' wide, limited by the size of the
sheet of rubber two people could carry. The Gettysburg Motel just rebuilt
their 1600 ft^2 of collectors on a new roof. Their accountant figures these
double-glazed units pay for themselves every 14 months, for domestic water
heating. That would shorten a lot for pool heaters, with no glazing or
EPDM rubber replacement. 

Nick

---

From: [email-masked] (Nick Pine)
Date: 9 Oct 1996 15:56:45 -0400

>of those things!  Please post a source!

The trade price of Heliotrope General's DTT '94 Combo was $74.80, including
sensors and a 110 VAC recepticle, as of 18 months ago. (800) 552-8838.

Nick

---

From: Dick Lambert <[email-masked]>
Date: Wed, 09 Oct 1996 21:49:55 -0700

At 08:50 AM 10/7/96 +0100, [email-masked] wrote:

>>I missed the first posts on this subject but I gather that someone
>> was looking for some ideas on solar pool heating in a cold
>>climate.  Will someone with a 12 year old solar pool heater in
>>Minnesota do?  Minnesota - you know, the place where summer is two
>>months of bad skiing.

>>garage roof.  They are plumbed in parallel to keep the head loss low.
>>A small Grundfos pump, controlled by a $100 controller that senses
>>exceeds the pool water temp.  It also will run the solar pump if the
>>roof temperature is below 40 to prevent freezing.  I use a "bubble
>>pack" solar cover.  I haven't had any maintenance expenses on the
>>system in 12 years and it typically keeps the pool between 88 and 90
>>(the pump turns off at 90) .  It is able to bring the water up about 6
>>or 7 degrees per sunny day if we have a long cool cloudy stretch.
>>In short, the pool has always been at a comfortable temperature anytime
>>the outside was warm enough for anyone to be interested in swimming.
>>We typically open the pool in late May and close it in early September.
>>
>>Dick Lambert

>I have been trying to do something like this in an area of the world where
>black pipe of any kind does not exist (northeast Poland). Whatever I want,
>I will have to import or carry it in from a long ways off, so I want to get
>it right at the start.
>
>What is a grundfos pump?

Grundfos is a brand name of a pump - I believe the parent company is in
Germany.  All I have is the US address: Grundfos Pumps Corp, 2555 Clovis
Avenue, Clovis, California 93612, USA (209) 292-8000.  I'm using a 1/12
horsepower model #UP-26-96BF which has a bronze volute (case) and a
stainless steel impellor.

>How many gallons per minute are going through it?

I estimate that it's pumping about 9.5 gallons/minute.
>Who makes the controler?

Goldline Controls division of Independent Energy Inc., 42 Ladd Street,
East Greenwich, Rhode Island, USA (401) 884-6990, (800) 343-0826.  I'm
using their model CM30 - X0102 which is a pool & spa unit with a 55 to
110 deg F adjustable maximum pool high limit ($80 in 1985).  It uses a
model INS-1 insolation sensor ($10 in 1985) and a model SC-1/2 water
temperature sensor ($10 in 1985).
>
>What exactly is black poly piping? 'Poly' what?

Flexible high density polyethylene.  I used a 1" 80 psi rated product
under the brand name of "Excel" made by Granse Corporation, 21670
Hamburg Avenue, Airlake Industrial Park, Lakeville, Minnesota 55044, USA
(612) 469-2191, (800) 328-4509.  I paid $110.00 per 1000 foot coil in
1985. This type of pipe is connected with  radiator hose clamps and
barbed fittings (male barbed fitting on both ends) which slip inside the
pipe thereby reducing its internal diameter.  In addition to the time
and expense of making the connections, each fitting creates a high
pressure drop compared to the normal fittings used with rigid pipe.   I
special ordered long length coils to minimize the problems, expense, and
pressure drop many connections would cause.  

> Is it flexible?

Yes - see below.

>Is it resistant to decay from the sunlight and hot water?

Yes, the manufacturer claimed that they use a an "ultraviolet proof"
resin that does not deteriorate in sunlight.  I have not seen any
deterioration in the pipe at all.  In fact, I deliberately left the odd
lengths I had left over on the garage roof alongside the solar heater. 
They have been left in the sun subject to everything the solar heater
piping has had to face except for the pool water inside.   Therefore,
they have had a tougher environment since there was no water to carry
away the heat - they just baked in the sun.  I just brought a piece
that's been on the roof since July 1985 down and it flexes just like it
was brand new - absolutely no sign of hardening or brittleness at all. 
I just bent the piece into a 2 foot diameter circle with virtually no
noticeable flattening of the pipe - there was no flattening with a 3
foot diameter circle.

> How much total space does a 1000' coil take up?   Is it coiled tight or with space between the coils?

I laid the pipe on an 85 deg F day in four flat spiral coils that
started at about 3 1/2 foot in diameter and went out to about 11 feet in
diameter.  All four coils fit in an area of about 11 feet by 44 feet.

>Does it have any covering (glazing, glass or plastic) over it, or insulation under it?

No.  I thought about glazing but decided it was [A] too expensive to do
it with low maintenance glazing like glass, [B] to maintenance prone
with a cheaper plastic, and [C] likely to damage the EPDM roofing below
the glazing if I had installed it.  I took the lack of glazing into
account when I decided how much pipe to install.  I don't think there
would be much of an efficiency gain from insulating beneath the array,
however, I decided that I would add some kind of closed cell (not porous
to water) insulation beneath to protect the roof membrane if I ever did
need to glaze to increase capacity.

> Would that [glazing] make a significant difference?

Most definitely,  I would guess that glazing would at least double the
efficiency.  As it stands now I benchmarked my system as follows:  On
5/21/94 at 1:35 PM central standard time with no clouds and a 90 deg F
outside air temperature the solar heater delivered a 13 deg F
temperature rise (77 deg entering pool water temperature, and 90 deg F
leaving pool water temperature).  I got essentially the same results a
month later.  The temperature rise goes up due to the increased delta T
when the pool water is colder.

Hope this helps.
----

---

From: Dick Lambert <[email-masked]>
Date: Wed, 09 Oct 1996 22:04:33 -0700

> sloped roof, it is very hard to blow the water out of the bottom half

The manufacturer (Granse) claimed that they use a an "ultraviolet proof"

BUT, if the coils were mounted in anything but a horizontal surface they
would have to be blown out well.  I used to have the same outfit that
blew out my underground sprinklers blow out my solar heater too until
they blew UP my $80 multiport pool valve - then I started doing it
myself with a small 3/4 hp compressor.  The sprinkler outfit used a
trailer mounted compressor of the type used for jackhammers and it blew
the system dry (and no it did not unwind my solar coil like a New Years
eve part favor).

---

From: Dick Lambert <[email-masked]>
Date: Wed, 09 Oct 1996 22:06:50 -0700

---

From: [email-masked] (John Harrison)
Date: Tue, 15 Oct 1996 20:35:14 GMT

>pool in late May and close it in early September.

Befoe this topic dies - can you tell me how putting the pipes in
parallel "keeps the head loss low"?
I am thinking of doing this deal, and I need to know the best way to
get the water from my 3" pool pipes up onto the roof which is some
distance away (say 25 feet horizontal ) and up to the roof (say 15-20
feet above the filter pump).
There will be a fair resistance (??) as the pipe narrows to the black
poly pipe diameter - will my filter pump (1.5hp) handle the pressure
load from the height as well as the resistance from the smaller tube ?
What "valves" need to be put in this system?

---

From: [email-masked] (Andrew McKegney)
Date: Thu, 17 Oct 1996 17:05:28 GMT

>What "valves" need to be put in this system?

96:10:17

Dear John

There are a couple of ways to keep the head loss low. The most
efficient is to use several (many) coils in parallel (each coil being
supplied (and returned to) by a common pipe) rather than one big coil
with one inlet and outlet. The supply and return lines must be a least
the same size as your regular plumbing -- or -- a second less
desirable method of reducing pressure drop -- substancially reduce the
flow rate of the water through the piping, which will also allow you
to use smaller diameter piping.

Note: the principle of using multiple parallel paths is used in almost
all commercial solar pool panels. They typically have dozens (if not
hundreds) of parallel tubes per panel. This is why they have such low
pressure drops while handling all of the flow from the pool filter.

Note 2: To collect the most heat from any solar panel, you want it to
operate as cool as possible. The warmer it is, the more heat it loses
to the air around it. So you want to push as much water as you can
through the panels to keep their temperature down. This will be a
problem if you have only one continuous coil as the pressure drop
through it will be very high, and this will seriously reduce the flow
rate through your filter.

To solve the problem of high pressure drop in a single coil system you
can install a diverter valve in the pool plumbing (between the supply
and return lines of the solar system) and open in to allow some water
to bypas the solar system and go staight back to the pool.

BTW all solar plumbing should be on the line returning to the pool,
after the filter (this keeps the crap out of the solar panels).

A third way to reduce the "effect" of the pressure drop from a solar
system on a pool pump is to use a seperate pump to circulate the water
throught the solar panels. This does involve the additional expenses
of the pump and the operation of the pump (and perhaps a seperate
timer/controller).

To answer your question as to whether or not you 1.5 hp pump could
"handle the pressure", it will work but pump much less water. The
result is you will likely get insufficient filtering to keep your pool
clean. A well installed commercial system might see a 4 psi pressure
drop between solar on & off. A single coil system could easily see a
20 psi pressure drop.

Another point to mention about pressure drops, is that in closed
systems (not open to the air) the height of the solar panels is not a
factor (except when first filling the system) because the weight of
the column of water going up equals the weight of the column of water
coming down. If the system is "open" with a vacuum breaker or other
method the column of water going up is not offset by the water coming
back.

Andrew McKegney C.E.T.

---

From: [email-masked] (Guy Macon)
Date: 18 Oct 1996 15:38:32 GMT

Expanding on a point in Andrew's excellent post;

>method the column of water going up is not offset by the water coming

This is 100% true in any reasonable solar pool heater, but there is an
exception that the industrial folks migh run into...

The weight of the column of water going down only offsets the first
11 meters or so of the column of water going up.  Past that, a
partial vacuum forms in the line going down.  This assumes 1
atmosphere at the outlet.  A pressurized loop can go higher and
still have a full syphon effect.

The real problem is when you expect the water going down to cool
something.  The partial vacuum (water vapour, really) does not
cool the pipe walls as well as water would...

---

From: Dick Lambert <[email-masked]>
Date: Fri, 18 Oct 1996 18:41:27 -0700

> parallel "keeps the head loss low"?

A pump only pushes so much water through a given resistance so if you
put four 1000' pipes in parallel you'll have 1/4 of the resistance of
4000' in series.

> load from the height as well as the resistance from the smaller tube ?

No. I used a separate Grundfos brand circulating pump that taps into my
2" pool line just after the filter and returns the heated water on the
other side of an elbow - it isn't meant to run without the main pool
pump running.  I've got about a 10' rise to the garage roof.  I
recommend that you run as large a pipe to the roof as practical to keep
losses down.

> What "valves" need to be put in this system?

I would suggest six.  One one each of the four 1000' coils to aid in
blowing them out (assuming your in an area that freezes) plus two more
to isolate the heater from the main pool circulating line is case you
solar system develops a leak.

-- 
Dick Lambert 				800 Brenner Avenue
President				Roseville, Mn 55113-1904
R.C. Lambert & Associates, Inc.		(612) 483-1492
Energy Conservation Consulting Engr	[email-masked]

---

From: [email-masked] (John Harrison)
Date: Mon, 21 Oct 1996 20:10:57 GMT

amongst other stuff

>solar system develops a leak.

I am not in an area that EVER freezes, but I thought that I would need
a valve at the pump end to prevent " backflushing " from  the water up
on the roof when the pump goes off, and also some other sort of valve
to stop the down pipe (outlet) from the solar collector from
collapsing from negative pressure when the pump goes off (won't the
water in this pipe just run down into the pool otherwise?).
Excuse my ignorance - I know nothing about solar, pressure, flow,
valves etc!!!
What sort of valves are we talking about????

---

From: Dick Lambert <[email-masked]>
Date: Mon, 21 Oct 1996 21:52:50 -0700

John Harrison wrote:
> I am not in an area that EVER freezes, 

Then you wouldn't really need the individual valves on the four parallel
coils.  I'd still recommend the two isolating valves at the pool pump in
case the system developes a leak you shut it off without having to turn
off your main pool pump.

>but I thought that I would need
> on the roof when the pump goes off

This isn't a problem unless you have a leak in the pipe above that opens
the system to the atmosphere.

> and also some other sort of valve
> collapsing from negative pressure when the pump goes off 

This isn't a problem

(won't the
> water in this pipe just run down into the pool otherwise?).

See above

> valves etc!!! What sort of valves are we talking about????

I'd suggest what's know as a ball valve - they are available from any
decent do-it-yourself store.  Get one that has a full sized port, i.e.,
the hole thru the rotating ball should be the same size as the pipe the
valve it for.

---

From: [email-masked]
Date: Wed, 23 Oct 1996 02:30:55 GMT

Could this type of system be converted to warm a house?

Is there any way to use a pond in the winter to heat a house?

---

From: [email-masked] (Andrew McKegney)
Date: Thu, 24 Oct 1996 03:15:46 GMT

>What sort of valves are we talking about???? 

The valve you are speaking of is a "check-valve" or "foot valve"(if at
the end of a pipe) They are designed to allow water to flow in only
one direction- ie: not drain out or back. They are available from any
plumbing store, or if you want PVC, a good pool service
store/department.

You will have a problem, if your system plumbing is "closed" meaning
not open to the air (anywhere), with a vacuum/negative pressure in the
plumbing at the highest point when the pump is off.

The solar industry uses vacuum breakers to allow air into the plumbing
if a negative pressure develops in the panels. This prevents plastic
panels, softened in high heat - non-operating conditions, from
collapsing. (and these products are designed to be in the sun - unlike
most poly pipe!)

Again, vacuum breakers can be purchased from a good plumbing store.

Shut off  valves should be used on the supply and return lines as
noted by others.

Andy McKegney C.E.T.

---

From: [email-masked] (John Harrison)
Date: Sat, 26 Oct 1996 19:56:15 GMT

I am still reading this with interest, but remember I live in brisbane
, Australia where it NEVER freezes!
I am pretty sure I am gonna try this setup with the poly pipes!
A couple of questions remain....
The pool pump (1.5HP) will have to lift the water to the roof (about
20ft) - will it have enough or too much pressure for a 1000 ft run of
polypiping? I am going to try one coil initially to see how i go. Can
I use the plastic securers (that you get in the garden/ hardware
shops)over the pipe barbed interconnectors or should I use metal
clamps?

What difference does it make to the system if there is gate or ball
valve somewhere after the pump but before the solar collector?
These restrict the diameter of whatever pipe they are put on. What
does it do to pressure vs flow??? Are they really necessary?
Won't the pump be struggling against this restriction since it has a
fixed output rate??? Does this harm the pump?
But better than blowing all the joins (not that there will be too
many) and having water all over my roof!
(My currnet pump runs from 40-100 psi depending on how dirty the
filter is!)
Does it really make any difference (to pressure, flow etc)where I make
the first join from the pvc 50mm PVC pipe (from the pump outlet) to
the 19mm black poly pipe.
A restriction is a resriction !!! 
It is a lot easier for me to do this join at ground level near the
pump and then run the black poly up to the roof coil and back to the
pool. It is a lot harder (i.e. more work and money) to run the 50mm
pvc pipe up onto the roof and then make the connection to the coil. If
that makes a big difference to efficiency etc can someone tell me how?