Title: Sunshine water heaters
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00026372/00001
 Material Information
Title: Sunshine water heaters
Alternate Title: Bulletin 93 ; Florida Agricultural Extension Service
Physical Description: Book
Language: English
Creator: Rogers, Frazier
Publisher: Agricultural Extension Service, University of Florida
Publication Date: February, 1938
Copyright Date: 1938
 Record Information
Bibliographic ID: UF00026372
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aab7772 - LTQF
amt7204 - LTUF
01823550 - OCLC
002570890 - AlephBibNum


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The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source

site maintained by the Florida
Cooperative Extension Service.

Copyright 2005, Board of Trustees, University
of Florida


(A Revision of Bulletin 68)

February, 1938

(Acts of May 8 and June 30, 1914)
Agricultural Extension Service
University of Florida, State College for Women
And United States Department of Agriculture
Wilmon Neiwell, Director


Professor of Agricultural Engineering
University of Florida College of Agriculture

Fig. 1.-A sunshine water heater on the side of a house in southern
Florida. Often these heaters are placed on the roof.

Bulletins will be sent free to Florida residents upon application to

Bulletin 93



R. P. TERRY, Chairman, Miami
W. M. PALMER, Ocala
H. P. ADAIR, Jacksonville
J. T. DIAMOND, Secretary, Tallahassee
JOHN J. TIGERT, M.A., LL.D., President of the University
WILMON NEWELL, D.Sc., Director
A. P. SPENCER, M.S., Vice-Director and County Agent Leader
JEFFERSON THOMAS, Assistant Editor
CLYDE BEALE, A.B., Assistant Editor
E. F. STANTON, Supervisor, Egg-Laying Contest
RUBY NEWHALL, Administrative Manager
W. T. NETTLES, B.S., District Agent
H. G. CLAYTON, M.S.A., District Agent, Organization and Outlook Specialist
J. LEE SMITH, District Agent and Agronomist
R. S. DENNIS, B.S.A., Assistant District Agent
A. E. DUNSCOMBE, M.S., Assistant District Agent
R. W. BLACKLOCK, A.B., Boys' Club Agent
E. F. DEBUSK, B.S., Citriculturist
A. L. SHEALY, D.V.M., Animal Industrialist2
HAMLIN L. BROWN, B.S., Dairyman
N. R. MEHRHOF, M.AGR., Poultryman2
D. F. SOWELL, M.S., Assistant Poultryman
WALTER J. SHEELY, B.S., Agent in Animal Husbandry
C. V. NOBLE, PH.D., Agricultural Economist2
CHARLES M. HAMPSON, M.S., Agricultural Economist, Farm Management
R. H. HOWARD, M.S.A., Asst. Agr. Economist, Farm Management
GRAY MILEY, B..A., Asst. Agr. Economist, Farm Management
D. E. TIMMONS, M.S.A., Agricultural Economist, Marketing
A. E. MERCKER, Field Agent, Cooperative Interstate Marketing1
R. V. ALLISON, PH.D., Soil Conservationist2
MARY E. KEOWN, M.S., State Agent
LUCY BELLE SETTLE, M.A., District Agent
RUBY MCDAVID, District Agent
ETHYL HOLLOWAY, B.S.H.E., District Agent
ANNA MAE SIKES, B.S., Nutritionist
VIRGINIA P. MOORE, Home Improvement Agent
ISABELLE S. THURSBY, Economist in Food Conservation
CLARINE BELCHER, M.S., Clothing Specialist
A. A. TURNER, Local District Agent
BEULAH SHUTE, Local District Agent

1 In cooperation with U. S. D. A.
2 Part-time.



A supply of hot water is needed in every household. In Flor-
ida there should be little difficulty in utilizing the rays of the
sun to heat water for domestic purposes. In the peninsular
section of the state many solar heaters are operating satis-
factorily at present. Some have been installed for more than
10 years and are still functioning satisfactorily. Many are
"home-made", although many commercial heaters are to be
found in the state.
The basic information for this bulletin was obtained from
a sunshine heater constructed on the College of Agriculture
farm by the Department of Agricultural Engineering of the
University of Florida. Temperature of the water in the stor-
age tank was recorded constantly by a recording thermometer
for 18 months. The highest temperature attained during that
period was 191 Fahrenheit, which was reached on September
19. There were very few days during the entire year when
the temperature of the water in the storage tank did not reach
120 Fahrenheit.
The design of the heater is very simple. It consists of an
absorber and a storage tank, with connective pipes. The water
circulates through the coils in the absorber due to thermo-siphon
action. That is, water upon being heated becomes lighter and
will rise to a higher level if a circulating system is provided.
The storage tank is placed higher than the heating element
(absorber) so that the cold water will replace the hot water
from the absorber when circulation begins. The water will con-
tinue to circulate in the system as long as there is a difference
in temperature between the water in the absorber and that in
the storage tank.
The absorber is the heart of this type of heating system. The
more efficient the absorber the better will the water be heated.
Utmost care should be exercised to see that the absorber is
properly constructed.
Figure 4 gives a front view of the absorber coils with the
tank connections for both solar absorber and auxiliary heater.
The auxiliary heater is not a part of the solar system but may
be desired in event the solar heater does not supply an ample
quantity of hot water. This would be especially desirable where
the water demands were variable. The storage tank must be
higher than the absorber. The cut-off valve as shown in Fig.
4 may be of the globe type and operated by hand or of the
swinging check type which operates automatically. Many sys-
tems are in operation without check valves of any kind and give
very good results. If the automatic swinging check is used

Florida Cooperative Extension

it must be very light and easily operated or the thermo-siphon
action of the water will not have sufficient force to operate it.
If the globe type is used it should be conveniently located so
as to make its operation less troublesome.
The absorber is usually placed on the roof on account of the
protection afforded by being above the ground out of the reach
of children who might damage the glass. So far as operation is
concerned it might be placed on the ground. The angle at
which the absorber is placed to the horizontal or ground surface
is very important. Higher temperatures are secured when the
rays of the sun strike the absorber at right angles. Since the
sun's rays strike the earth at different angles during different
seasons of the year, and since it is fairly easy to heat the water
during summer, the absorber should be so arranged that the
sun's rays will strike it at a 90 degree angle about the first of
March and the first of October each year. For the latitude of
Florida, placing the absorber at an angle of 40 degrees to
horizontal will permit the sun's rays to strike it at an angle
of 90 degrees during October and March, and has proven satis-
factory. Figure 2 shows the position in which the absorber
should be placed on the roof. The pipes in the coil beginning
at the cold water inlet should be on an upward incline so that

Fig. 2.-Diagram of end

of absorber, showing angle at which the absorber
should be set.

j/ /i-w Cold waer

ND V IE W OF A Ba5omz S.

Sunshine Water Heaters

the water upon being heated will rise in the absorber. The
lead out pipe from the absorber to the storage tank also should
be inclined upward.
Figure 3 gives a cross-sectional view of the absorber. The
bottom of the absorber is constructed of tongue and groove
material on which is placed two inches of insulating material.
Care should be exercised to waterproof this material, if it is
absorptive. Coal tar and roofing paper may be used for this

J'/be Z g / 9 J S

.2 Concrete I V

5 c r 7 o/ or 0A s oP* A'

Fig. 3.-Cross-sectional diagram of the absorber, concrete, pipes,
coil and sash.

To increase the absorption material as well as to hold the
coils in place, about 2 inches of concrete of a 1-2 mixture is
placed on the insulation. While the concrete is still soft the
coil should be imbedded to 1/ of the diameter of the coil pipes.
In constructing the absorber it has been found convenient to
place the coil on the insulating material and support it with
2" blocks until the concrete can be placed. Thick sheet metal
has been used in place of concrete with very good results, the
coil pipes being fastened on the sheet metal instead of being
imbedded in the concrete. The coil is made of l%" black or
galvanized wrought iron pipe. The joints should be well leaded
to prevent leakage. The inside of the absorber should be painted
dull black to increase its efficiency.
Glass for the absorber is of the type used in ordinary window
sash, the amount used governed by daily hot water require-
ments. One square foot of unobstructed glass surface should
be provided for each gallon of hot water needed per day. While
window sash has been used for absorber covers, it is not as
satisfactory as frames of metal where no cross braces are used
and the glass length is the full width of the absorber. Water
collects above the cross braces in a wooden sash frame, causing
the wood to rot. On the metal frame, ends of the glass can
be held in place by metal straps, allowing rain water to run
off the frame more completely. For glass supports light angle
irons for ends and inverted metal T beams in between are much


Fig. 4.-Complete diagram of a sunshine water heater system, showing absorber, tank and auxiliary heater, with
connections. Connecting pipes from absorber to tank are only indicated by breaks in the pipes.

Sunshine Water Heaters

more durable than wooden sash frames. Putty should be used
to seal the joints and prevent rain water from getting inside
the absorber.
The most common size absorber to supply 30 gallons of hot
water per day is one 4 feet wide and 71/2 feet long.
Absorbers have been constructed with sheet copper instead
of concrete, and copper pipes instead of iron pipes. Copper,
being a much better conductor of heat than concrete and iron,

Co/ld water

~2" /nsl /d/on.,

cold W/a /.r

of storage tank, showing connections and

//olt ;ate-

Fig. 5.-Cross-sectional diagram

Florida Cooperative Extension

gives a heater of greater efficiency. Usually it is more expen-
sive. Where sheet copper and copper tubing are used the tubing
should be soldered to the copper sheet to get best results.
It is essential that the absorber be constructed as nearly
air-tight as possible to prevent loss of heat by radiation.


An insulated storage tank is necessary in a solar hot water
system to keep the water hot over night as well as maintain
heat for two or three days in event of no sunshine. The tank
used in most solar systems is the same type tank used in other
hot water systems. Figure 5 shows the most common method
of insulating tanks. Build a square box so that the tank when
placed in it will have at least 2 inches of clearance on all sides.
The tank is then placed in the box and insulation poured around
it. Ground cork, dry sawdust or shavings may be used. Be
sure that there are no leaks in the tank that will keep the insula-
tion wet, for these materials lose most of their effectiveness
as insulators when they become wet. Asbestos may be used
as an insulator but is usually more expensive. If the absorber
is any great distance from the storage tank the pipes connect-
ing these should be insulated. For short distances this is not
If the absorber is to be used where there is danger of the
water freezing, provision should be made for draining the water
from the system. It would require several days of low temper-
atures to result in any damage from this cause.

The following bill of material will give an idea of the require-
ments for a 30-gallon tank capacity heater.

5 18"x48" single window light
2 pieces 2"x4"x8' lumber
2 pieces 2"x2"x4' lumber
12 pieces 1"x4"x8' tongue and
groove flooring
36 sq. ft. 2" insulation
5 pieces 1/2"x3"x4' battens
8 pieces %"x4"x4' cleats
22 dozen No. 12 wood screws
6 lbs. assorted nails
% sack Portland cement
3 cu. ft. sand
1 qt. black asphalt paint
1 qt. lead and oil paint

18 pieces %" black pipe 6' long
2 pieces %" black pipe 8' long
19 pieces %" close return bends
40 pipe straps for %" pipe
1 %" tee
1 %" ell
1 cut-off valve
1 %" gal. pipe and cap 1' for vent
1 30-gal. range boiler
20 pieces 1"x4"x8' tongue and
groove flooring
1 bbl. insulation (ground cork,
sawdust, etc.)

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