re: solar pool heating
4 oct 1996
andrew mckegney drones on:
>>>>>as a solar professional for 18 years (motivated by environmental
>>>>>concerns) i am perplexed by the lack of acknowledgment of commercially
>>>>>available solar pool heating products.
i hereby acknowledge that commercially available pool heating products are
too expensive, and the charlatans who sell them ignore pool insulation.
>>still perplexed? pool heaters aren't that bad, just too expensive, but pool
>>insulation sucks. perhaps you have not noticed this. so here's a clue :-)
>>heating a swimming pool with existing technology is like bailing a boat
>>with no bottom. you "solar pool heating professionals" need to get your
>>heads out of the sand and act more sensibly and responsibly on behalf of
>>your clients, and look at this as more of a system. energy in, and energy
>>out, with a lot more emphasis needed on the out part, at the moment.
>we don't build pools. a professional solar installer tries to get the
>pool owner to use a solar blanket.
good idea. now suppose you are a dermatologist. a patient comes in to your
office who has just been run over by a car, and he is bleeding profusely from
his missing arm. he asks for help with his itchy scalp. what do you do?
pat him on the back, give him a prescription for some ointment, and
send him on his way? is that professional? i know, i know, what can
you do if people do not want or will not accept the right kind of help?
you tell them what they need, and they ignore you. so maybe you end up
thinking they don't really need what you think they need, or that what
you have to sell today is really what they need, which is not true.
hvac criminals act the same way.
this needs more common sense, leadership and education, along with a bigger
picture, less specialization, and more high-school physics and arithmetic.
>>it is irresponsible to sell people heaters, when what they need is
>>insulation. it is irresponsible to use lots of fuel to heat a pool,
>>when one could use use far less fuel and pollute the atmosphere far
>>less with a little more imagination and insulation.
>you might consider that solar energy isn't a fuel in the conventional
>sense. there is no pollution associated with the use of a solar system.
sure. that's obvious. what should also be obvious, but isn't, is that pools
need more insulation, somehow. new pools built differently, retrofits, truly
effective thermal covers, structures to enclose pools, etc. it seems foolish
to attach expensive pool heaters to such miserably-insulated pools, from an
engineering point of view. if pools were better insulated, it would seem less
foolish to use existing pool heaters, and fewer square feet of them. you
might call this a rational engineering point of view. not necessarily how
everyone else thinks.
another reason to avoid using expensive pool heaters is that energy is so
cheap in this country. but making an inexpensive plastic film pool heater
on a roof seems ok, from that point of view. a square foot of any sort of
solar collector can only collect the heat equivalent of a gallon or two
of oil per year, so if oil and gas are cheap, solar collectors need to be
cheap to compete with them economically, no? or, they need to serve more
than one purpose, like a transparent roof or transparent siding for a house,
since houses need roofs and siding anyway, or a sunspace that adds some
daytime floorspace and storage space and perhaps a place to grow things
to a house. or a place to put a hot tub or a swimming pool.
>>>>these things seem like expensive overkill to me, for pool heating.
>>>>sure they work, but why spend $5/ft^2 when you can make a swimming
>>>>pool collector for 50 cents/ft^2? and why just extend the season a bit
>>>>when you can make something that works year-round. and where are the
>>>>r10 commercially-available pool covers?
>let's see a "year-round" solar collector for 50 cents/ft^2.
yeah, let's see that, andy :-)
>one that isn't going to freeze,
drain the system back into the pool at night.
>that's going to last for 15 years+ with no maintenance,
sounds good to me, but is that necessary? many homeowners mow lawns, paint,
clean out gutters, wash dishes, mop floors, etc. (not me of course.)
>that doesn't look like garbage on a roof ......
chacun a ses ordures. but how do you know what this will look like?
it ain't been designed yet. architects and others have ways of making
lots of things look pretty, and there are many different architectural
forms with equivalent engineering performance.
let's see. perhaps you would say that a black roof is not inherently ugly.
putting a layer of clear plastic over that doesn't change the appearance
much. now we seem to be talking about how to keep the clear plastic from
flapping in the wind, right? if you were a piece of plastic film, lying flat
on a roof, with another flat piece of plastic right underneath, and you were
recently wet underneath, would you want to flap in the wind? maybe.
what would keep you from doing so? vacuum? the wet adhesive force?
seems worth a try. perhaps we are overcomplicating this. i think there
are lots of ways to solve this problem, some being more aesthetically-
acceptable than others. and why such emphasis on aesthetics, anyhow?
iraquis are dying because of the way we use energy in this country.
>>still wondering... it seems stupid to sell people pool heaters to extend
>>the season a few weeks, when with a fairly tiny amount of engineering and
>>arithmetic, you can make solar-heated pools that are usable all year.
>yeah, in theory. try it sometime!
i'd love to, but i don't have a pool, and i'm not in that business. you are.
>>>>solar pool heating should be extremely easy, with a built-in thermal mass
>>>>and low water temperatures and high air temperatures and insolation.
>>>>so why aren't more people doing it?
>because people get misinformation about solar from people who know
>nothing about what really works. from people like you.
i disagree. i think this business is fucked-up.
>>>i have always recommended conservation before insolation (insulation
>>>before sunshine) with any solar product...
>>nice platitude. so why aren't you making an r10 pool cover?
>it's not a platitude, it's the truth.
too bad people don't follow your recommendation, huh?
>btw i don't have the millions to risk in developing a product
>pool owners wouldn't buy.
i don't think it would take millions. i think it might take 2 weeks,
depending on what you mean by "it." and i think people would happily
buy "it" if "it" were reasonably priced and performed well, and you
put "it" in an alternative energy catalog like jade mountain's
(firstname.lastname@example.org.) or sold kits to home depot.
>>>...in the real world, people with swimming pools tend to prefer easy
what is an easy solution?
is it easy to put a $900 30' wide x 48' long plastic film greenhouse over an
existing pool, and hinge a 300 pound 24' x 36' cover made with $300 worth of
beadboard and 2x4's to a pipe along the 36' north edge, and haul the cover up
to a 45 degree angle automatically with a $200 dc winch when the sun shines
and the pool needs heat, in december? i think so. should the south glazing
be translucent polyethylene film that needs recycling every 3-5 years, at a
cost of $60, or very clear single layer polycarbonate that lasts for 20 or 30
years, and costs $1000? should people grow food and flowers and sit outside
next to their swimming pools in december? would the second one of these things
be cheaper or easier to build? i think so, the 10th? i think so. how many
people would like to own one? how will we know until we build one? you say
you know already, but people don't have choices like these now.
>>>as you acknowledge, you do not have a swimming pool, and, from the
>>>sounds of it have never built a real solar pool heating system, i
>>>would suggest that you are ignorant of the practicallities of
>>>operating a pool and a solar pool heating system.
>>true. and i suggest you are know too much of these "practicallities."
>>also, it appears you can't spell. not a good sign for a solar physicist.
>you would suggest that too much knowledge is a bad thing? interesting
>comment from someone in an educational institute.
i'm suggesting that some of what you "know" is not true.
and i am not presently institutionalized :-)
>>>you should be aware that even if you use a solar cover all the time,
>>>you are still going to have to heat the pool - ideally with a solar system.
>>oh, i'm aware of that. can we use numbers here? i mean, are you capable of
>>doing that sort of arithmetic, andy, as a self-styled "solar professional"?
>>or are you very confused about solar arithmetic and high school physics?
>>we need fewer "solar professionals" like that...
>no, only confused by selective readers. ie: those who ingore facts
>that support their arguements.
i wonder what you mean by that. how do you ingore a fact?
that might work better than these discussions...
>>now suppose the cover and heater are the same... :-)
>you mean like existing solar bubble balnkets????
yes, during the daytime. altho something more vertical would work a lot better
in wintertime. but we need something that is a lot more insulating at night.
>>>solar systems have to be large because pools require a large
>>>amount of heat - that is just a matter of physics.
>>sure. i wonder if you are familiar with this "matter of physics."
>>few people are, i've noticed. let's talk a lot more about that...
ok. give me some numbers. how much heat does a swimming pool need?
>>>solar pool heating is not new, commercial products have been around
>>>for at least 25 years, and they work well
>>bullshit. pool insulation is rotten.
>what's pool insulation got to do with solar pool heating? we're
>talking about solar panels here.
you may have hit on the problem here.
>>>and last a long time (15+ years) if desighned and installed properly -
>>>with little or no maintenance!!!!!!!
>>so why aren't more people doing it? something to do with money?
ok. what do we do about that? make solar heaters with rooftop plastic films,
ie make them cheaper? add value to the _system_, by making it possible to
swim all year? reduce the cost with a more balanced _system_, with more
insulation and less solar heating?
>>...poorly engineered products? like blue-colored "solar pool blankets"? :-)
>solar blankets are not solar pool heaters.
true, in the usual sense. but why are they blue?
they would let in more sun if they were clear.
>>or piss-poor insulating pool covers? would you insulate your house with
>>swimming pool cover material? no way... just how gullible do you think
>>people are, andy, when you imply these are "well-engineered products"?
>you don't seem to know the distinction between solar blankets and
untrue. should i add some exclamation points!!! ? :-)
>>they are expensive kludges, that hardly seem engineered at all to me. if
>>that's all you have to sell, too bad. but existing pool covers are no good,
>>and saying they are won't make them so. that is a lie. do you ever get
>>angry when people lie to you? should professionals lie? should they know
>>the basic science of their profession, or just sell things?
>yes i get angry when people lie to me. i also get angry when people
me too. and should professionals lie? and should they know
the basic science of their profession, or just sell things?
>existing pool covers are much much better than nothing!
>right now that is the alternative.
you mean, like, this afternoon....?
>>>try that with loose plastic sheeting on a roof!!!!!!
i would if i had a swimming pool, perhaps this afternoon. maybe i should
put one up in my attic. no, too heavy... it's 100.6 f up there now, and
47.7 f outside. i'm thinking of closing some attic windows.
>>try what? who said the plastic was "loose"? we don't want it to blow away,
>>or suffer from wind fatigue. how can we avoid that? there must be 50 simple
>>ways. sven tjernagel of mechanicsburg, pa has built several thousand flexible
>>rooftop water heaters like these, over the last 20 years. are you looking for
>>problems or looking for solutions?
>why isn't sven's product being sold to heat pools?
>i've never heard of it, and i would like to.
i don't know the answer to that question. i suspect they are being used for
some swimming pool heating applications now. chlorine compatibility may be a
problem. a heat exchanger might be needed with an epdm collector, but that's
probably not a big deal. run a few $4 solid pvc pipes around the pool maybe.
or make a concentric tube heat exchanger out of some of the plumbing. do
solaroll collectors degrade from pool chlorine? is that why they wear out?
we might use oxygenation, or aqua-air's silver-copper ion system to reduce
or eliminate chlorine. environmentalists and fish don't like chlorine.
sven is now definitely out of that business, and mostly building water tanks
for fire protection systems now. but many of those several thousand solar
heating systems are still in use at hotels and laundrys and so on. he aimed
at commercial and industrial installations, some of them having thousands of
square feet of collectors. in his system, the epdm rubber needed replacing
every 7 or 8 years, because it was a trickle-down system rather than filled
with water, with dry hot spots. that also meant he needed more water flow than
normally needed, i think. and i suppose there were stagnation problems in some
installations. he didn't intall these systems on roofs with a pitch more than
1:1 either, as i recall. he said he aimed at businesses than homeowners
because businesses were used to the idea of maintenance, and didn't mind
replacing the rubber every so often, but homeowners expected systems to last
at least 20 years, and didn't want to do any maintenance at all. does that
make sense? i'm sure it does to you.
i just tried to call sven, and got his answering machine. perhaps you'd
like to talk with him:
sven tjernagel solar systems
477 woodcrest road
mechanicsburg, pa 17055
(717) 761-5858, -8951 fax
he's an interesting and practical person who knows a lot about solar heating,
including radiant floor heating and hot air distribution with duct heat
exchangers. good practical stuff. but like many people who really know how
to do solar heating, he's out of that business. he site-built heat storage
tanks with epdm rubber liners inside plywood boxes until ul stopped approving
site-built tanks (will csa accept them?), then switched to a nicer design,
something like a tall circular sheet metal swimming pool, lined with foam
and epdm. he stopped installing unpressurized hot water tanks upstairs when
people complained about "rats in the walls," ie hot water cavitation in
the vertical pipes...
>>>the status quo works, and has been arrived at from trial and error in the
>>>solar industry. i'm all for inovation, but not just for inovations' sake.
>>there's something to be said for the status quo, and you have said it,
>>but it does not seem to me that you are "all for innovation."
i wonder how long you will parrot back this status-quo defense.
>>>prove to me it works and lasts as long or longer, has less
>>>impact on the environment and i'll go with it.
>>that's not my job, andy. i'm not the "solar pool heating professional."
>no, but you are advising people who are looking for practical solar
>you owe it to them to tell them what is available in the market,
not if they are not practical solar solutions.
>i've just noticed that your e-mail address origionates from an .edu
just now, huh?
>i must conclude from this and your attitude that you are an
>"ivory tower idiot" - long on the theoretical and ignorant of the practical.
ok. go ahead. conclude.
>you seem to be blaming the solar industry for the sins of the
not exactly. not even close, actually.
>the two are not related.
i wouldn't say that at all. would they were moreso.
>if you care to take a close look, you'll find that pool campanies usually
>don't sell solar systems -
interesting. why not, exactly?
>solar companies do.
now why is that... could it be that pool companies know that solar heating
their existing pools is foolish? unlike your customers, after you have
handcuffed them to chairs and given them your professional advice?
>pool companies - from what i've seen- don't give two hoots what it costs
>a pool owner to operate their pools. they just want to sell the pool and
>the chemicals that go with it.
ok for the moment. but i think that might change, with a few good examples.
>(the chemicals are another environmental horror story)
that might be improved a lot with aeration, a fountain here or a waterfall
there, and by letting some water flow through the pool, if heating water or
water itself were not so expensive. one might use rain, for hot tubs, and
5 parts per _billion_ of copper ion in water will stop algae. throw some
pennies in the filter?
>solar is a nuisance to them -they'd rather you bought a gas heater (from them)
>and run it on "high" all the time. (that way you'll need more pool chemicals)
i think this can change, if a few people do things right.
>any reputable solar company, and there are many, will insist that
>before you use a solar system, you use a solar blanket. the only solar
>blankets available are really just evapouration retarders, not
>insulation blankets.(and the best ones are transparent/translucent to
>let the sun into the pool)
>there is a very simple reason for this. no one has figured out a way
>to cover an 800 sq. ft. kidney shaped pool with an insulating blanket
>that can be removed and replaced in 2 minutes (that doesn't cost over $300)
i think you may be defining the problem too narrowly here, but perhaps we
need to do more figuring out. tiny cold bubbles are excellent insulators.
greenhouse people have been experimenting with them since 1975, and they
have a harder task than swimming pool coverers. can we have bubbles on top
of the water itself, somehow, under a plastic film to stop evaporation?
polyethylene macrospheres that are filtered out when we want to swim?
how about just deflating a polyethylene film pillow full of tiny soap bubbles
before swimming, pumping it out and letting it sink to the bottom? or doing
that with a weighted neutrally-bouyant styrofoam cover, by making it slightly
heavier than the pool, and lowering it with a few ropes or letting some water
fill a few cavities rather than air? this is not rocket science.
>these are parameters that are set by the end user.
i think you may be defining the problem too narrowly here.
many end-users would be delighted to swim in december.....
>as i have already mentioned, even the existing easy-to-use, not unsightly,
>cheap, solar bubble blankets are difficult to sell
awww... too bad... poor andy...
>(and get the customers to use) (this is true even when you point out
>they will need a solar system twice as large if they don't use a blanket!!)
and all this is for what? another month or so of pool use?
>the average consumer can be a pretty dumb animal !
especially when bamboozled by "professionals."
>they will buy for their convienence and their pocket-book, but
>not for the environment or energy efficiency (if it means more
>than a 3 year payback).
how about for december swimming, or a nice warm place to sit outdoors
during the day, or to grow food or flowers?
>this is the real market. rant and rave all you wish about what people
i know, i know, they should buy your solar pool covers and heaters.
>they do what they do, and will continue to do so.
forever and ever, unchanging unto the last syllable of recorded time...
>i consider it a small victory to turn people from natural gas, oil or
>electricity to solar for heating their pools.
i do too. but we look for easy victories, right? like drunks who look for
wallets under lamposts at night, because there is not so dark there.
>i think it is a crime to heat a pool with a fossil or nuclear (fission)
>fuel and damage the environment in the process.
no argument there, and fusion is very far away. but it's also a crime
to push pool heaters when what people need is pool insulation.
>until some company invents and perfects the r10 pool blanket -and i
>don't think that it will happen in my lifetime-
perhaps because in your world, nothing ever changes.
>the best solution is still the manufactured solar product,
>installed by solar professionals.
ah yes, those nice shiny expensive bailing buckets for bottomless boats,
installed by crack solar professionals. "here you are m'am. we are so happy
to meet your pool heating needs."
>the payback on these systems vs. installing and
>operating a conventional natural gas heater is typically 2-3 years.
almost as short as the payback for closing the windows of a house
in december, vs buying more gas to heat it...
>if you wish to complain about my spelling, go ahead - i don't have a
i don't either.
>and i consider it very petty of you to comment on it -
>i'd say it shows a pretty arrogant attitude.
okokok. i won't say another word about your spelling.
i will let this aspect of your professioalism speak for itself.
>get some real-world experience with pool heating -solar or other -
>please before advising pool owners on what they can do.
no. now would you like to talk about solar arithmetic? :-)