How
to Build a Solar
Hot Water System
by
John Canivan
Printing
January, 2004
Sunny Future Press, Wantagh, NY
Copyright John Canivan 2002
ISBN 0-975498-0-2 $35
All
rights reserved. No part of this book may be reproduced or transmitted in any
form or by any means electronic or mechanical without the express permission of
the publisher. How
to Build a Solar Hot Water System is an easy to follow, step-by-step
87-page book with clarified theory and dozens of illustrations. It was written
for anyone concerned about saving money, and saving our little blue-green planet.
MATERIALS
for collectors
1.
Two rolls of 50-foot 20” aluminum flashing
2. Four .060-inch thick 4X8 sheets of Kalwall from: www.solar-components.com
3.
Twenty 1X4X8 pine with few or no knots
4.
Four ½X4X8 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 pain
10.
Angle iron for mounting
11.
Sixteen ¼ X 3 lag bolts, sixteen ¼ X 1½ inch machine bolts with nuts
and washers
12.
1 ¼ inch and 2 inch drywall
screws
13.
One pound of 1½ inch galvanized nails with small heads
14.
PLUMBING SUPPLIES
a.
Eight 3/8
to ½ adaptors
b.
Four ½ inch T’s
c.
Two ½ X ½ X ¾ T’s
d.
One ¾ inch T
e.
Four ½ inch unions
f.
Eight ½ inch elbows
g.
One ¾ inch street elbow
h.
One ¾ sweat to ¾ female pipe
i.
One pressure relief valve
j.
Four sixty foot rolls of 3/8 ID copper tubing
k.
½ - inch rigid copper tubing type L
l.
¾ - inch rigid copper tubing type L or M
m.
Solder and flux
Table
of Contents
Chapter I SOLAR HOT WATER SYSTEMS
Passive Hot
Water
9
Active Hot
Water
10
Heat
Transfer
11
Parallel
Flow
13
Serpentine
Flow
14
Theory
20
Materials
21
Pounding jig construction
instructions 22
Absorber
plate construction instructions
23-27
Step 1. Cut framing
boards 28
Step 2. Assemble frame 29
Step 3. Fasten
collector bottom and sides 30
Step 4. Construct tube
bending jig
31
Step 5. Bend copper
tubing 32
Step 6. Install
insulation
33
Step 7. Drill inlet,
outlet and vent holes
34
Step 8. Install
absorber plate
35
Step 9. Install
serpentine tubing 35
Step 10. Install sweat union
38
Step 11. Cut serpentine tube supports 40
Step 12. Install tube supports 41
Step 13. Touch up
42
Step 14. Install Kalwall
42
Chapter
IV COLLECTOR
MOUNTING
Theory of orientation and pitch
44
Assembly of horizontal and vertical supports
45
Chapter V HOT WATER STORAGE
Thermodynamic theory 46
Multi tank theory
48
Heat exchange coil theory
49
Chapter
VI HEAT
STORAGE VAULT CONSTRUCTION
Step 1. Tank
preparation
51
Step 2.
4X4 supports
51
Step 3.
Bottom platform
51
Step 4.
Placing tanks on platform
52
Step 5.
Framing the storage vault
53
Step 6.
Insulating the storage vault
54
Step 7.
Installing sides
54
Step 8.
Installing sheet insulation
55
Step 9.
Making and installing the inner lid
55
Chapter
VII HEAT
EXCHANGE COILS
Theory
56-62
Assembly 61
Inner lid construction and installation
63-64
Chapter
VIII CIRCULATION
AND VAULT PLUMBING
Mounting platform
66
Plumbing overview
67
Details of plumbing
68
Assembly
69
Chapter
IX COLLECTOR
PLUMBING
Overview
70
Union T assembly
71
Main output junction assembly
72
Main input junction assembly
73
Chapter X THE SENSOR SYSTEM 74
Chapter XI FILLING AND DRAINING THE SYSTEM 75-76
Chapter XII OTHER SOLAR APPLICATIONS 77
GLOSSARY 78-79
Author’s Note 80
Experimental Heat Storage Vault 81-87
If you have $2000 (in 2002) and a few weeks of labor to invest this book could save you $50,000 or more in hot water and home heating costs. You folks with carpentry and plumbing skills have a definate advantage but anyone with a grasp of the English language, capable of or willing to learn can install a solar hot water system and there are qualified carpenters and plumbers available who can help you anytime. A good solar heating system is not free. It seems like it should be; after all heat from the sun is free why isn’t a solar heating system? Fossil fuel contractors throw in oil burners for free when they sign you sign up for a five-year contract. Why doesn’t Mr. Sunshine give us 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 our birthright like the air we breathe or the water we drink. Our sun is enough to sustain us, and still we burn the fluid remains of our ancestors to stay warm. Buckminster Fuller, who coined the saying “Doing more with less,” compared fossil fuel with the starter motor of an automobile. He believed that the modern technological world we live in was started with a little boost from fossil fuel consumption. Once started technology should free us from dependence on non-renewable energy. Our starter motors are growing weary. It’s time to start the motor of social harmony, get back to our roots and welcome in the “Solar Age”.
Before diving into the building plans for an active solar hot water system I’d like to discuss a few basic concepts regarding light, heat and heat transfer.
How
does light make heat?
Most of the sun’s energy that makes the 93,000,000-mile journey is in the form of visible and ultraviolet light. Heat is produced when high frequency light is converted into low frequency infrared radiation. Ultraviolet and visible light easily passes through glass, however when they strike a darkened surface they are converted into long wave infrared radiation. The glass or special solar glazing traps these long waves. This is known as the greenhouse effect. CO2 is also capable of trapping long wave radiation. Small amounts of CO2 keep our planet nice and warm. Too much CO2 in the atmosphere may transform our forest into deserts. Is it not ironic that we are using the same effect to save the planet that is destroying the planet?
Now
I understand the Greenhouse effect. Could you explain what heat 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 vibrates the hotter it becomes. It’s as simple as that.
OK I get it. Light causes molecules to move
faster. So how do these fast moving light excited molecules get into my hot
water system?
They
don’t. If they did you would have a contaminated system and you’d get sick
and die, because collector fluid usually contains antifreeze. The molecules that
are excited by the sun never enter your domestic hot water. Only molecular
movement is transferred in the double insulated flat plat plate collector system
that I am proposing.
Wouldn’t it be easier to use plain old ground
water for collector fluid than you wouldn’t need antifreeze?
In
gentle climates perhaps, however if you travel north of Georgia the batch tank
would loose too much heat in the evening to be practical. Under extreme
conditions the water in the tank might even freeze. For cold climates it is
always best to separate the heat collection area from the heat storage area.
How about that drain away system?
Good
point. There is another type of system called the DRAIN BACK or DRAIN DOWN
system that allows heated water to drain back into a holding tank when sensors
indicate that no heat gain is possible. Some of these systems employ heat
exchange tanks and some use the solar heated water directly. These systems do
save that hot water in the pipes with a system of automatic valves and relays,
but it is more complicated, more expensive and more prone to problems than the
double insulated heat exchange system.
OK! You convinced me. Should I get my tools? I
feel like hammering and drilling and sawing and screwing.
That’s
good, but hold onto these feelings a bit longer. I want to be sure you
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 study at R.P.I.
Come
on, it will be fun. Think of it as plumbing 101.
That sounds less threatening. I’ll give it a
try.
That’s
the spirit. I’ll 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 to compare and contrast two types of flat plate
collectors, the parallel and the serpentine.
Since the parallel collector is the most popular commercially available
system I’ll discuss this one first. Here is an example of a flat plate
parallel pipe collector system:
FLOW
RATE THEORY
PARALLEL
FLOW DYNAMICS
This
parallel collector is designed to transport collector fluid from the bottom of
the collector to the top via a network of parallel pipes. Notice that 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 is because
incoming fluid pressure is greatest at the base of the first pipe and outgoing
fluid pressure is smallest at the top of last pipe. If the top and bottom pipes are large the pressure difference
is moderated and the flow rate in each of the parallel pipes is more uniform.
These collectors may be connected in series because the top and bottom
distribution tubes are so large. It is unfortunate that the flow rate is minimal
at the center of the collector where most of the heat is concentrated. Other
problems associated with the parallel flow with collector include cost and
leaks. Half inch and two inch copper tubing is expensive, not to mention the
dozens of special T fittings and all that solder. One small, undetected leak on
one of those T fittings could become catastrophic mess.
SERPENTINE
FLOW DYNAMICS
The
serpentine collector consists of one long continuous flexible tube so there is
no problem with uniform flow rate. The size of this flexible tubing is an
important consideration. Quarter inch copper tubing is inexpensive, however it
restricts the flow rate too much. Half inch flexible 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, and ease 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 and puts an unnecessary burden on the circulator pump. Connecting the serpentine collectors in parallel alleviates this problem. A two-collector system works fine. A four-collector system works even better. It is very important to bend this 3/8 copper tubing carefully to avoid kinks. This will insure that the flow rate is uniform throughout the serpentine collector array hooked in parallel.
If you want to learn how to assemble and install this serpentine ,closed loop solar hot water system you'll need to purchase the book. My easy to understand, 87 page, fully illustrated book, How to Build a Solar Hot Water System has a retail price of $40, but is now available for $35. "SUN HEAT " an auto run Multi Media CD-ROM is included at no additional cost.
How to Build a Solar Hot Water System ebook version $15
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