Fw: Hot water at summer camp [RE-wrenches]

Sat Mar 24 10:15:14 PDT 2007

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> Chemistry was never my strong point-- an understatement-- but I believe " 
> acid rain " has more to do with some of the other pollutants coming from 
> coal burning, rather than CO2. Sulfer dioxide, I think, as in sulfuric 
> acid. Our shallow aquafir and surface watewr also tends to the lower ph 
> due to pine and oak trees. Pine needles especially keep the surrounding 
> soil a lower ph.. Any chem majors or soil scientists care to chime in?
>
> Drain Back systems-- not to be confused with Drain Down systems !-- are 
> not only better when overheating and stagnation is likely. They are also 
> more efficient due to the following issues;
> 1--water is a better conductor than antifreeze solutions
> 2--if you use a large,unpressurized tank, with the heat exchange to 
> pressurized water on the output side, the the water circulating thru the 
> collector will be cooler.
>    The efficiency curve of a flat plate collector is sensitive to inlet 
> water temp. So if we want to maximize our BTU input, we need to work with 
> the     coolest fluid temps practical .
>
> Some other advantages;
>
> 1-- with an unpressurized tank, it is easy to put heat in from other 
> sources, say a wood boiler.
> 2-- it is also easy to take heat out, say for radiant slabs, or fan 
> convectors.
>
>
> Now for the Summer camp--
>
> I never got answers needed to now the details of appropriate design-- and 
> ' the devil is in the details' so I'll make some assumptions;
>
> 1-- summer camp means june, july and august
> 2- location is Texas, daytime temps in the 90's or hotter
> 3- incoming water temp is 70-80 F, unless the source includes a large 
> aboveground storage tank, which might well be hotter.
> 4-shower temps will be 95-120F  [ sweaty kids may well like a cool shower 
> at 4PM after a day in the Texas sun !]
> 5- 14 showers at 2gpm x 5min equals 140 gals in less than an hour, per 
> cabin
> 6- there are 21 systems ----lets assume 20 cabins and one kitchen, which 
> has a different load profile and higher hot water temp needed.Up to 180F.
> 7- at least some of these structures are grouped , say less than 50 ft 
> apart.
>
> For the kitchen, I would then think about an appropriate size glazed 
> collector-- I've always been happy with the AET collectors --and an 
> unpressurized site built tank with submerged SS tanks as the output heat 
> exchange. If the tank is at least 2 gal/ sq ft of collector, efficiency 
> should be quite high and water temps low enough to limit scaling. If the 
> water supply is chlorinated then 316, rather than 304, SS should be used . 
> If a commercial water heater is used for 180F sanitizing dish washing is 
> used, then they may have, or want to install a softening system designed 
> for their needs.
>
> For the cabins, I'd consider using unglazed pool collectors, roof mounted 
> on the sunniest cabins with appropriate size drainback heat exchange tank, 
> exterior location, to twin 80 gal electric tanks in the shower area.If 
> there were an unusual cool cloudy spell predicted, the elements could be 
> activated at off peak times. The larger the drainback tank, the better the 
> carry thru for those unusual days. Underground , insulated, piping in 
> sealed plastic drain pipe [ sealed to prevent condensation building up in 
> the drain pipe] would connect the cabins to the main storage/ heat 
> exchange tank.
>
> If some of my assumptions are off, glazed collectors could be added in 
> series, or substituted entirely.
>
> A whole different option would be heat pump water heaters, running at nite 
> for the next days hot water. If the cabins have AC--[surely not at summer 
> camp!], that is used almost every nite, de-superheaters would give free 
> hot water and increase AC efficiency.
>
> note to Bill-- thanks for the compliment. Guess I'm way out of the box now 
> !?
>
> Ken Schaal
> www.commonwealthsolar.com
>
>
>
> ----- Original Message ----- 
> From: "Darryl Thayer" <daryl_solar at yahoo.com>
> To: <RE-wrenches at topica.com>
> Sent: Saturday, March 24, 2007 6:03 AM
> Subject: Re: Hot water at summer camp [RE-wrenches]
>
>
>>
>> Hello
>> My understanding is that as CO2 desoloves in water it
>> becomes acid.  As this acid passes through the
>> limetone of soil and rock it becomes CaCO3? This makes
>> hard water.  As the water is heated the CaCO
>> precipates as the hard water products.
>>
>> When I am concerned with overheating and stagnation, I
>> use a closed water drainback system.  I am concerned
>> with usnig antifreeze in stagnation systems because
>> the antifreeze breaks down and becomes acid.  Just
>> heating water does not.  The closed water drain back
>> system must be properly drain when the pump shuts
>> down.  These systems survive here in Minnesota, they
>> cost as much as antifreeze systems.
>>
>> Darryl
>> --- Ken Schaal <ken at commonwealthsolar.com> wrote:
>>
>>>
>>> Acid neutralizer tanks are on p.2937 of the curent
>>> Grainger catalog #398.
>>> Limestone [ marble chips] raises the ph. As it does
>>> so, it dissolves and
>>> could thus precipitate if conditions are right.The
>>> rate at which it
>>> dissolves is a function of the water ph, and the
>>> amount of flow. In a hot
>>> copper pipe, or collector, it will form a coating
>>> which is both protective
>>> and somewhat inhibiting of conduction.
>>> Here in the flatlands of the SE, central Va. with
>>> shallow 50 wells in sandy
>>> soil we have a ph about 5.5. Up in the mountains
>>> with limestone formations,
>>> it's less of a problem.
>>>
>>>
>>>
>>>
>>> ----- Original Message ----- 
>>> From: "Bill Loesch" <solar1online at charter.net>
>>> To: <RE-wrenches at topica.com>
>>> Sent: Friday, March 23, 2007 8:00 AM
>>> Subject: Re: Hot water at summer camp [RE-wrenches]
>>>
>>>
>>> >
>>> > Ken,
>>> >
>>> > I have never heard of the marble chips technique
>>> before. Do I understand
>>> > that the marble chemically reacts with the acid
>>> water as well as becomes a
>>> > precipitate site for hard water scale? If there is
>>> a chemical reaction,
>>> > how
>>> > long does the marble last?
>>> >
>>> > My compliments for thinking outside of the box.
>>> >
>>> > Is this marble tank something you home brew or is
>>> it commercially
>>> > available?
>>> > Details please.
>>> >
>>> > Thanks again,
>>> >
>>> > Bill Loesch
>>> > Solar 1 - Saint Louis Solar
>>> > 314 631 1094
>>> >
>>> > ----- Original Message ----- 
>>> > From: "Ken Schaal" <ken at commonwealthsolar.com>
>>> > To: <RE-wrenches at topica.com>
>>> > Sent: Thursday, March 22, 2007 6:32 AM
>>> > Subject: Re: Hot water at summer camp
>>> [RE-wrenches]
>>> >
>>> >
>>> >>
>>> >> A simple solution to copper corrosion due to acid
>>> water is to install a
>>> >> neutralizer tank, which uses marble chips to
>>> raise the ph. Thicker copper
>>> >> will only delay the problem.
>>> >> There will be more lime deposits to precipitate
>>> onto very hot surfaces,
>>> > like
>>> >> coffee makers, which can be cleaned with vinegar.
>>> For boilers, and batch
>>> >> heaters subject to high temps or stagnation,
>>> appropriately placed valves
>>> >> will facilitate cleaning with acid.
>>> >>
>>> >> One of the many reasons to use drainback systems,
>>> especially now that
>>> >> very
>>> >> low wattage pumps with high head are available.
>>> >>
>>> >> Ken
>>> >>
>>> >>
>>> >>
>>> >> ----- Original Message ----- 
>>> >> From: "Tom Lane" <tom at ecs-solar.com>
>>> >> To: <RE-wrenches at topica.com>
>>> >> Sent: Wednesday, March 21, 2007 8:26 AM
>>> >> Subject: Re: Hot water at summer camp
>>> [RE-wrenches]
>>> >>
>>> >>
>>> >> >
>>> >> > Hi All,
>>> >> > I strongly recommend the SunEarth Copper Heart
>>> versus the Progressive
>>> > Tube
>>> >> > (TCT) PT-40. The TCT PT-40 uses a .030 copper
>>> sheet that is welded to
>>> > form
>>> >> > a tube. We have had lots of problems with this
>>> leaking in agressive
>>> > water.
>>> >> > The Copper Heart  uses extruded .058 DWV copper
>>> pipe--almost twice as
>>> >> > thick. I suggest a Rheem or Rudd 80 or 120
>>> gallon wrap around heat
>>> >> > exchange tank if the water is agressive(low
>>> ph., iron oxides, CO2 or
>>> >> > O2,
>>> >> > etc.. with a SunEarth or AET Drainback or
>>> pressurized glycol system.
>>> >> > Gator Tom
>>> >> >
>>>
>>>
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>>
>>
>>
>>
>> ____________________________________________________________________________________
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> 


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