Hot Water Software [RE-wrenches]

Sat Oct 6 18:53:08 PDT 2001

Hi Travis,

I will try and clarify why I personally prefer to install metal solar 
pool heating panels as opposed to plastic.

Metal is a conductor of heat and plastic is an insulator.  Plastic 
panels heat water just as well as metal panels, but to accomplish this, 
the plastic panels need many dozens of small diameter water passageways 
that are more prone to clogging.  Metal panels absorb heat more readily, 
so they can have absorber fins between the larger diameter water 
passageways, resulting in less back pressure on the pump.

Typically plastic panels are mounted flush on a roof and secured with 
straps.  This leads to debris build-up and eventually reduces the 
longevity of the roof.  Metal panels are rigid so they can be mounted on 
a couple of stringers a few inches above the roof.  This method of 
attachment is structural and allows the roof to breath and shed debris.  
Metal panels are also non-flammable. Plastic panels are more easily torn 
by severe winds and can make flapping noises.

Since the 1990's I have personally installed many thousands of pool 
panels, some of these installations were removing and re-installing 
panels to allow for re-roofing.  This allowed me to see what works best. 
 I work on some very large and expensive homes and my customers want the 
best.  I have a sample piece of a new plastic and metal panel as well as 
a sample of a metal and plastic panel that is 15 years old.  It is easy 
to see which looks best after a decade goes by.

Plastic panels are cheaper to purchase and many people have them 
installed in Los Angeles, but I never sell or install plastics.  People 
selling plastic panels warn potential clients that plastic is not harmed 
by pool chemical and copper will deteriorate.  Most pool heater cores 
are copper and many pools are plumbed with copper, especially the older 
ones.  Proper pool chemistry will not harm copper pipes in the metal 
pool panels.  With that said, I once encountered a customer (85 years 
old) that poured a 20 lb bag of shock treatment into his pool, the 
product was sucked straight up into the panels and damaged two panels as 
well as leaving a purple ring around his pool.  This was one isolated 
case.

I installed 8 pool panels last week to replace 8 metal panels that were 
installed in 1981.  But with the big demand for grid-connected systems 
in Los Angeles I do not anticipate installing many more pool heaters.  
At least until the LADWP $6.00 per watt rebate expires.  I am installing 
at least one 2.6 kw system weekly.  This week I did Don Foster's house 
the writer of the show Darma and Greg and my next 13 installs sold are 
to actors and producers.  Having installed solar panels since 1982 I am 
noticing a dramatic and exciting increase in the demand for solar energy 
in Los Angeles.  I wish I could install more systems but I personally 
drill and seal every hole on my customers roofs and these PV systems 
require a lot of roof penetrations.

I hope this helps,

Graham Owen
GO Solar Company

Travis Creswell, Ozark Solar wrote:
> Hi Graham,
> 
> I have only installed a few solar pool heaters (in 10 years) and see it 
> as a
> potentially good business.  I'll refer to your suggestions the next time 
> I
> get a call about it.  They seem like naturally good sellers but.....
> 
> At you convenience could you elaborate some more about metal vs. plastic
> panels.
> 
> Thanks
> 
> Travis Creswell
> Ozark Solar
> 
> 
> ----------
> >From: graham at solarexpert.com
> >To: RE-wrenches at topica.com
> >Subject: RE: Hot Water Software [RE-wrenches]
> >Date: Thu, Oct 4, 2001, 8:49 PM
> >
> 
> >Hi  Travis,
> >
> >I have installed a number of solar pool heating systems in the Los 
> >Angeles area.  I also use the surface area of the pool for sizing 
> >systems.  The surface of the pool is where almost all of the heat is 
> >gained and lost.  Evaporation on the surface a pool can significantly 
> >reduce the water temperature (thermal mass), especially so when the wind 
> >
> >is blowing.
> >
> >What I look for when sizing a system is for three specific site 
> >conditions. 1. Is the pool in the shade or in direct sunlight during 
> >most of the day?  2. Can the solar panels face south, as opposed to east 
> >
> >or west?   3.  Is the pool sheltered from prevailing winds?
> >
> >If all of these site requirements are positive, I start with a minimum 
> >of 50 to 60% coverage.  Length of the pool x Width of the pool x 55%.  
> >If the panels face east and the pool is partially shaded I would install 
> >
> >100% coverage.
> >
> >The average pool in L.A. is 15' x 30' = 450 square feet x 55% = 248 
> >square feet.  Since the average pool panel is 4' x 10' I would divide 
> >248 by 40 = 6 panels. 
> >
> >The temperature the client wants the pool must also be considered.  The 
> >trickiest part of most pool installations is how to get two 2" PVC pipes 
> >
> >and the sensor wire from the pump to the side of the house where they go 
> >
> >up to the roof.  I also closely check the condition of the roof and if 
> >the ceiling inside is open beam.
> >
> >I prefer metal panels but some of the plastic panels seem to have 
> >improved lately.
> >
> >I have more info on this web page www.solarexpert.com/poolheat.html
> >
> >I hope this helps,
> >
> >Graham Owen
> >GO Solar Company.
> >
> >
> 
> 
> 

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