How to Build a Solar

7/29/2019 How to Build a Solar

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How to Build a Solar

Hot Water Systemby

John Canivan


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Printing January, 2004

Sunny Future Press, Wantagh, NYCopyright John Canivan 2002ISBN 0-975498-0-2 $35

All rights reserved. No part of this book may be reproduced ortransmitted in any form or by any means electronic or mechanicalwithout the express permission of the publisher. How to Build a SolarHot Water System is an easy to follow, step-by-step 87-page book withclarified theory and dozens of illustrations. It was written for anyoneconcerned about saving money, and saving our little blue-green

planet. For more information log onto: www.JC-SolarHomes.com

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MATERIALS for collectors

1. Two rolls of 50-foot 20 aluminum flashing

2. Four .060-inch thick 4X8 sheets of Kalwallfrom: www.solar-components.com

3. Twenty 1X4X8 pine with few or no knots

4. Four X4X8 CDX plywood

5. Four 1X4X8 sheet insulation R value 5 or better

6. Clear silicon caulking

7. Aluminum foil and some felt paper

8. One gallon of roofing tar

9. One gallon of oil base paint
http://www.jc-solarhomes.com/http://www.addtoany.com/share_save#url=www.jc-solarhomes.com%2Fhow_to.htm%20&title=How%20to%20Build%20a%20Solar%20Hot%20Water%20System&description=http://www.solar-components.com./http://www.jc-solarhomes.com/http://www.addtoany.com/share_save#url=www.jc-solarhomes.com%2Fhow_to.htm%20&title=How%20to%20Build%20a%20Solar%20Hot%20Water%20System&description=http://www.solar-components.com./


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10. Angle iron for mounting

11. Sixteen X 3 lag bolts, sixteen X 1 inch machine boltswith nuts and washers

12. 1 inch and 2 inch drywall screws

13. One pound of 1 inch galvanized nails with small heads

14. PLUMBING SUPPLIES

a. Eight 3/8 to adaptors

b. Four inch Ts

c. Two X X Ts

d. One inch T

e. Four inch unions

f. Eight inch elbows

g. One inch street elbow

h. One sweat to female pipe

i. One pressure relief valve

j. Four sixty foot rolls of 3/8 ID copper tubing

k. - inch rigid copper tubing type L

l. - inch rigid copper tubing type L or M

m. Solder and flux

Table of Contents


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Chapter I SOLAR HOT WATER SYSTEMS

Passive Hot Water 9Active Hot Water 10Heat Transfer 11Parallel Flow 13

Serpentine Flow 14

Chapter II ABSORBER PLATE CONSTRUCTION

Theory 20Materials 21

Pounding jig construction instructions 22Absorber plate construction instructions 23-27

Chapter III COLLECTOR BUILDING INSTRUCTIONS

Step 1. Cut framing boards 28Step 2. Assemble frame 29Step 3. Fasten collector bottom and sides 30Step 4. Construct tube bending jig 31Step 5. Bend copper tubing 32Step 6. Install insulation 33Step 7. Drill inlet, outlet and vent holes 34Step 8. Install absorber plate 35Step 9. Install serpentine tubing 35Step 10. Install sweat union 38

Step 11. Cut serpentine tube supports 40Step 12. Install tube supports 41Step 13. Touch up 42Step 14. Install Kalwall 42

Chapter IV COLLECTOR MOUNTING


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Theory of orientation and pitch 44Assembly of horizontal and vertical supports 45

Chapter V HOT WATER STORAGE

Thermodynamic theory 46Multi tank

theory 48Heat exchange coil theory 49

Chapter VI HEAT STORAGE VAULT CONSTRUCTION

Step 1. Tankpreparation 51

Step 2. 4X4supports 51

Step 3. Bottomplatform 51

Step 4. Placing tanks onplatform 52

Step 5. Framing the storagevault 53

Step 6. Insulating the storagevault 54

Step 7. Installingsides 54

Step 8. Installing sheetinsulation 55

Step 9. Making and installing the inner lid 55

Chapter VII HEAT EXCHANGE COILS

Theory 56-62

Assembly


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61Inner lid construction and installation 63-

64

Chapter VIII CIRCULATION AND VAULT PLUMBING

Mountingplatform 66

Plumbingoverview 67

Details of plumbing 68

Assembly69

Chapter IX COLLECTOR PLUMBING

Overview70

Union Tassembly 71

Main output junctionassembly 72

Main input junctionassembly 73

Chapter X THE SENSORSYSTEM 74

Chapter XI FILLING AND DRAINING THE SYSTEM 75-76

Chapter XII OTHER SOLARAPPLICATIONS 77


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GLOSSARY 78-79

AuthorsNote 80

Experimental Heat Storage Vault81-87

If you have $2000 (in 2002) and a few weeks of labor to invest this bookcould save you $50,000 or more in hot water and home heating costs.You folks with carpentry and plumbing skills have a definite advantage.This book is definitely for you. This book is also for anyone with a graspof the English language, capable of or willing to learn carpentry andplumbing skills. A good solar heating system is not free. It seems like itshould be; after all heat from the sun is free why isnt the solar heatingsystem? Fossil fuel contractors throw in oil burners for free when theysign you sign up for a five-year contract. Why doesnt Mr. Sunshine giveus the same deal? I guess Mr. Sunshine is just a mean old man.

We are all part of a vast, interdependent universe. Energy for life is ourbirthright like the air we breathe or the water we drink. Our sun isenough to sustain us, and still we burn the fluid remains of ourancestors to stay warm. Buckminster Fuller, who coined thesaying Doing more with less, compared fossil fuel with the startermotor of an automobile. He believed that the modern technologicalworld we live in was started with a little boost from fossil fuelconsumption. Once started technology should free us from dependenceon non-renewable energy. Our starter motors are growing weary. Its

time to start the motor of social harmony, get back to our roots andwelcome in the Solar Age.

SOLAR ELECTRICITY The photovoltaic power industry has a long wayto go before becoming a practical investment for the average consumer


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although some remote locations miles from the power grid find that it ismore practical to install solar than have power lines run to theirhouse. Government incentives and technological productionbreakthroughs are necessary before the photovoltaic industry blossoms.$5.00/watt is too much. When the price comes down to $1.00/ watt giveme a call. A typical $40,000 residential investment would take about 40years to reach payback. This is of course assuming that $40,000 hasthe same value today as it would have forty years from now. SolarElectricity is a beautiful thing, but for most of us the time is not right.Well have to wait a little longer until this growing technology becomesfeasible.

SOLAR HEATING Solar heating is feasible today. The average

American household consumes between 1000 and 2000 gallons ofnumber two fuel oil per year. Efficient use of the suns energy couldeasily cut this consumption in half or eliminate it entirely. The heating ofwater is perhaps the easiest, most cost effective solar project a personcan get involved with.

SOLAR HOT WATER SYSTEMS

What once was a luxury is now a necessity. Over 500,000,000households have or would like to have running hot water. In 1970 afriend of mine left the civilized comforts of a New Jersey home to seekout and experience the free, wild wilderness of an Adirondack hilltop inupstate New York. Jake loved the country life and swore that hed neverleave his mountain retreat. He endured the cold winters withoutelectricity and baseboard heating, but Jake still missed running hotwater. When spring came he took a 300-foot coil of black plastic tubingand connected one end to a spring high up on the mountain. He drapedthe remainder of the 300-foot coil on his roof and spread it out to coveras much surface area as possible. For a $50 investment and one hoursworth of labor Jake had himself a bona fide hot water shower. He madegood use of it whenever the sun was high on the mountain. I used it a


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few times myself. It works. The roof might look a little funny and the hotwater would sometimes run out sooner than youd like, but it did workwhen the sun was shining. When the sun disappeared the showerwould get very cold. Toward the end of summer water would freezeinside the plastic pipe when the spigot was turned off.

You might be interested in a simple system like this if you enjoy takingshowers when the sun shines. If you desire a more sophisticated hotwater system youll need to invest more time and more money. I will bediscussing several solar hot water designs. If you live in a very warmsunny area a simple passive batch heater is probably all youll need. Ifyoure interested in an automatic system that works well in cold climateswith a minimum amount of sunlight youll need an active array of flatplate collectors with a massive heat storage system. Parabolic-troughheat concentrating collectors work, however they are usually inefficient,expensive and impractical.

PASSIVE HOT WATER


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BATCH HEATERS In gentle climates like coastal California or almostany place in Florida where freezing is a rare occurrence a simplepassive batch heating system is all thats necessary. The batch heatercould be as simple as a water tank painted black. A more efficientsystem would enclose this black tank in an insulated box. Glass or

some form of glazing would be installed at an angle perpendicular to thesuns rays. This is a practical, cost effective passive solar hot watersystem, ideal for gentle climates. For more information about thissystem check out www.solarnet.org
http://www.solarnet.org/http://www.solarnet.org/


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ACTIVE HOT WATER

Active solar hot water systems are designed for those less gentleclimates. Although they are a bit more complicated and requireelectricity to run a circulator pump, active solar hot water systems

harvest a lot of energy and save you money.

How much money will they save me on my fuel bill?

Good question. The answer to this question will of course depend on:

1. Your location.2. The orientation of your roof.

3. The angle that you position your collectors4. The number of collectors used

5. How well you insulate the heat transfer pipes6. The size of your heat storage vault

7. The amount of insulation used on the heat storage vault8. The amount of hot water used

You are avoiding my question.

OK Its a fair question and Im going to give you the best answer I canfrom data on my collector performance and other environmental data.


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For my four-collector system with a storage vault of four 55-gallondrums I estimate a $500 savings per year on Long Island.

How much will the electricity cost to harvest all this heat?

Between $10 and $20 per year.

HEAT TRANSFER THEORY

Before diving into the building plans for an active solar hot water systemId like to discuss a few basic concepts regarding light, heat and heattransfer.

How does light make heat?

Most of the suns energy that makes the 93,000,000-mile journey is inthe form of visible and ultraviolet light. Heat is produced when highfrequency light is converted into low frequency infrared radiation.Ultraviolet and visible light easily passes through glass, however whenthey strike a darkened surface they are converted into long waveinfrared radiation. The glass or special solar glazing traps these long

waves. This is known as the greenhouse effect. CO2 is also capable oftrapping long wave radiation. Small amounts of CO2 keep our planetnice and warm. Too much CO2 in the atmosphere may transform ourforest into deserts. Is it not ironic that we are using the same effect tosave the planet that is destroying the planet?


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Now I understand the Greenhouse effect. Could you explain whatheat is?

With pleasure. Heat is a measure of the average motion of molecules.When light strikes an object it causes the molecules to vibrate faster.

Intense light can ignite a log or melt steel. The faster an object vibratesthe hotter it becomes. Its as simple as that.

OK I get it. Light causes molecules to move faster. So how dothese fast moving light excited molecules get into my hot watersystem?

They dont. If they did you would have a contaminated system and youd

get sick and die, because collector fluid usually contains antifreeze. Themolecules that are excited by the sun never enter your domestic hotwater. Only molecular movement is transferred in the double insulatedflat plat plate collector system that I am proposing.

Wouldnt it be easier to use plain old ground water for collectorfluid than you wouldnt need antifreeze?

In gentle climates perhaps, however if you travel north of Georgia thebatch tank would loose too much heat in the evening to be practical.Under extreme conditions the water in the tank might even freeze. Forcold climates it is always best to separate the heat collection area fromthe heat storage area.

How about that drain away system?

Good point. There is another type of system called the DRAIN BACK orDRAIN DOWN system that allows heated water to drain back into aholding tank when sensors indicate that no heat gain is possible. Someof these systems employ heat exchange tanks and some use the solarheated water directly. These systems do save that hot water in thepipes with a system of automatic valves and relays, but it is more


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complicated, more expensive and more prone to problems than thedouble insulated heat exchange system.

OK! You convinced me. Should I get my tools? I feel likehammering and drilling and sawing and screwing.

Thats good, but hold onto these feelings a bit longer. I want to be sureyou understand a few things about fluid mechanics.

Forget it. I have a friend who is still baffled by the concept

of fluid mechanics and he spent four years of intense studyat R.P.I..

Come on, it will be fun. Think of it as plumbing 101.

That sounds less threatening. Ill give it a try.

Thats the spirit. Ill make this as painless as possible and even throw in

a few pictures to liven things up a bit. On the following pages I wish tocompare and contrast two types of flat plate collectors, the parallel andthe serpentine. Since the parallel collector is the most popularcommercially available system Ill discuss this one first. Here is anexample of a flat plate parallel pipe collector system:


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FLOW RATE THEORY

PARALLEL FLOW DYNAMICS


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This parallel collector is designed to transport collector fluid from thebottom of the collector to the top via a network of parallel pipes. Noticethat the top and bottom pipes are larger than the vertical pipes. There is

a reason for this.

Fluid mechanics favors an increased flow rate for the end pipes. This isbecause incoming fluid pressure is greatest at the base of the first pipeand outgoing fluid pressure is smallest at the top of last pipe. If the topand bottom pipes are large the pressure difference is moderated andthe flow rate in each of the parallel pipes is more uniform. Thesecollectors may be connected in series because the top and bottomdistribution tubes are so large. It is unfortunate that the flow rate isminimal at the center of the collector where most of the heat is

concentrated. Other problems associated with the parallel flow withcollector include cost and leaks. Half inch and two inch copper tubing isexpensive, not to mention the dozens of special T fittings and all thatsolder. One small, undetected leak on one of those T fittings couldbecome catastrophic mess.

SERPENTINE FLOW DYNAMICS


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The serpentine collector consists of one long continuous flexible tube sothere is no problem with uniform flow rate. The size of this flexible tubingis an important consideration. Quarter inch copper tubing isinexpensive, however it restricts the flow rate too much. Half inchflexible tubing is difficult to bend and fairly expensive. 3/8 inch tubing is

just right for the money. It has a reasonable flow capacity, low cost, andease of fabrication. What more could one ask for?

The main problem with a serpentine collector is flow rate restriction.

Even the larger half inch copper tubing restricts flow rate too much andputs an unnecessary burden on the circulator pump. Connecting theserpentine collectors in parallel alleviates this problem. A two-collectorsystem works fine. A four-collector system works even better. It is veryimportant to bend this 3/8 copper tubing carefully to avoid kinks. Thiswill insure that the flow rate is uniform throughout the serpentinecollector array hooked in parallel.


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