Note: Descriptions are shown in the official language in which they were submitted.
1 1~894 ~
The present invention relates generally to a low
temperature solar furnace and the like, being more particularly
directed tQ a method of and apparatus for collecting and storing
solar energy and selectively releasing this energy in a
controlled manner with a unitary passive system suita~le for
residential, commercial, industrial, and other related space
heating purposes.
Though the prior art discloses a variety of solar
systems which represent valuable and well recognized concepts
for providing heat, these systems suffer from a number of
deficiencies. For example, most of these heating systems consist
of an arrangement of "collectors" which are connected hy piping
or duct-work to a remotely heated reservoir or storage chamber
filled with rocks, water or the like, accordingly requiring
some configuration for the distribution of the absorhed heat
energy to the reservoir or storage chamber being heated. Systems
requiring such pumping or the like are "active" systems generally
comprised of separate and independent components that obviously
require pressurizacion and/or movir.g parts,
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1 16894 ~
and tend to be expensive, inefficient, and demanding of sub-
stantial installation space. Further, many such systems using
water have been subject to corrosion and freezing.
Illustrations of active system approaches, including
with the aid of reflecting surfaces, are described, for
example, in V.S. Letters Patent Nos. 1,853,480; 1,888,620;
3,841,302; 3,989,032; 3,946,944; 3,973,553; 3,987,786;
4,002,160; 4,026,269; 4,055,163; 4,082,143; 4,111,359;
4,112,920; and 4,112,922; German patents 4 41 151 and
25 11 740; and French patents 2,267,531 and 2,299,604.
Many of such proposals involved separate locations
for solar collection and storage, with the necessity for fluid
movement under power therebetween; and others also require
remote storage and/or powered fluid movement or the like and/or
powered fluid extraction from storage, with none providing an
integrated system wherein collection, absorption, storage and
provision of direct heat-exchange surfaces are provided in a
passive singly unitary structure.
More recent concepts for the use of solar roof-
mounted or attic systems also consistently involve at least
active systems, in whole or in part, such as are described in
Popular Science, January, 1979, "Solar Attic House", pp. 68-71,
146; U.S. Department of Agriculture Misc. Publication No. 1367,
March 1978; and in "Workshop on Energy Alternatives: The Goose-
sd/ - ~ ~3~
1~68941
brook Solar Home", Total Environmental Action, Inc., Harris-
ville, New Hampshire, June 19, 1977.
The present invention hereinafter described, on the
other hand, vastly improves upon prior art techn~ques by
providing an integrated passive arrangement of components
within a unitary physical configuration which functions
simultaneously in three modes; namely, (1) as a heat sink during
a period of solar energy absorption; ~2) as a storage medium
at the same location of the solar heat collected; and (3~ as a
heat source or heat exchange surface at the same location during
a period of energy extraction. None of these operating modes,
however, requires any moving parts or internal or bulk
movement of the fluid or the like, thus achieving a high degree
of efficiency at reasonable cost and minimum space requirements.
In its broad form, this invention envisions an insulated chamber
or enclosure having one of its sides comprising preferably a
multiple-layer-glazed, insulated solar window which functions
as a selective solar energy transmitting medium, and may
accordingly be referred to as a "transmittor". Interiorly of
this insulated chamber and coextensively juxtaposed the solar
window or transmittor are a plurality of heat sinks for
absorbing and storing the heat energy transmitted through the
"window".
Operable means are employed in this invention selec-
tively to change the character of the solar window from a solar
energy transmittor and therefore moderately heat insulating,
to being almost totally energy opaque. The solar window, when
energy opaque, is therefore "super-insulated". Alternatively,
another
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1 ~8941
arrangement will hereinafter be described whereby a separate
insulating means in the nature of a curtain may be selectively
interposed between the solar window and the heat sink means,
whereby to prevent any undesired heat transfer through the
solar window from the interior of the insulated chamber.
In summary of the above, therefore, the present
invention may be defined as a method of substantially passive
solar heating, that comprises, facing an insulated enclosure of
a building and the like with a solar-energy transmitting
surface; absorbing the heat of the solar energy entering the
enclosure through the transmitting surface within a medium dis-
posed within the insulated enclosure; simultaneously storing
the absorbed heat in the medium; flowing air into the enclosure
to contact and exchange heat with the medium and to exit the
heated air into the building to distribute heat therein.
The above method may be carried out by this invention
which provides in combination with a building, an integrated
low temperature, solar space and water-heating system comprising
an insulated enclosure operatively associated with the building,
at least one side of the enclosure comprising a solar trans-
mitter panel forming a part of an outer wall of the building,
the enclosure extending into the building a distance substan-
tially in excess oE the thickness of the outer wall, a heat
sink within the enclosure spaced inwardly from the transmitter
panel for receiving and absorbing solar energy through the
panel and simultaneously storing the heat of the energy therein
and thereat, the heat sink comprising at least one container
with heat absorbing material therein, the heat absorbing
material occupyina a siqnificant volume of the enclosure, means
~i'
sd~ r~ ~5~
~ ~8~ ~
including powerecl air moving means connected to the enclosure
for circulating air through another part of the building a.nd
through the enclosure in heat transfer relation with the
heat sink, at least one water tank in the enclosure in
radiant heat-receiving relation with the heat sink, the water
tank forming part of a hot water supply system for the building,
both the heat sink and the water tank being positioned in the
enclosure for direct exposure to solar energy received through
the transmitter panel, and movable insulating means within
the enclosure, the insulating means being movable between a
first position exposing the heat sink and water tank to heat
energy transmitted through the transmitter panel and a second
position screening the heat sink and water tank and minimizing
heat transfer between the enclosure and the outer environment
through the transmitter panel.
These and other features of the invention will be
more clearly understood from the following description taken
in conjunction with the drawings and are more particularly
pointed out in the appended claims. In the drawings, Fig. 1
is a perspective sectioned view of a typical building
utilizing an apparatus constructed in accordance with this
invention;
Fig. 2 is a perspective schematic view of one
embodiment of a typical transmitter panel with apparatus
operatively connected thereto for selectively making the
panel "super-insulated";
Fig. 3 is a vertical cross-sectional view of the
panel
sd/~ ~ -6-
.: .
1 ~6894 t
shown in Fig. 2 in the condition of being energy transparent;
Fig. 4 is a vertical cross-sectional view of the panel
shown in Fig. 2 filled with blown-in insulating material thus
in the condition of being "super-însulated" and energy opaque;
Fig. S is a schematic view of the solar invention
typically connected to hot-air type heat circulating ducts;
Fig. 6 shows an embodiment whereby a fle~ible
insulating curtain may be selectively positioned from the rear
to the front of the array of solar energy absorbers;
Fig. 7 shows an alternate embodiment of how the
flexible insulating curtain can be positioned around the array
of solar energy absorbers;
Fig. 8 schematically depicts a typical orientation of
how this invention may be employed for roof installations to
collect and store solar energy;
Fig. ~ is a view of a preferred or best mode embodi-
ment of the invention employed in the attic setting of Fig. 8,
and cooperating with a domestic hot water supply and a
supplemental lower floor wall furnace of similar construction;
Fig. 10 is a transverse section of Fig. 9 illustrating
an easterly elevation of the same;
Fig. 11 is a southerly, elevational view of the attic
system of Fig. 9;
Fig. 12 is a view similar to Fig. lQ, illustrating
different reflector positions; and
Fig. 13 is a graph demonstrating the performance
efficacy of the invention.
Referring now with greater particularity to the
-- 7
pc/ ~
~ 168~
drawings, Fig. l represents a broken view of a wall portion of
a typical building wherein a portion of a southerly facing
exterior wall lO is comprised of one or more solar windows or
transmittor panels ll. In the disclosed embodiment, such solar
transmittin~ panels consist of a rectangular frame with a
series of vertically spaced~apart grId elements carrying
translucent glass fiber reinforced polyester sheet material
bonded to the opposed surfaces thereof. obviously other
translucent or transparent facing materials may be employed.
Vertical wall portions 12,13, and 14 are insulated,
as are floor portions 15 and ceiling portion 16/ thus forming,
in conjunction with exterior wall panel ll, an insulated chamber
or cocoon typically represented as 17. Preferably, all interior
surfaces, with the exception of the solar windows ll, are
coated or otherwise covered with a reflecti`ve material.
Located interiorly of chamber 17 are a plurality of
water-filled, translucent, glass-fiber reinforced cylinders or
tubes 18 which preferably have a portion 9 of the cylinder wall
coated or otherwise colored dark so as to act as a heat
absorber. Though other tube shapes may be employed, the
preferred configuration is cylindrical because of its superior
structural qualities.
Tubes 18 are intented to function in any of three
modes; namely, (1) as a heat sink during the heat absorbing
phase; (2) as a heat storage unit following the absorbing
phase; and (3~ as a heat source during the heat extraction
phase. Each o~ these modes will be explained hereinafter in
greater detail.
-- 8 --
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~ ~ 6894 ~
This multi-mode characteristic of operation in a
unitary passive structure is one of the several important
features of this invention. By ~ay of conceptual explanation,
a "collectorN refers, in the state of the art, to a device that
performs both the functions of the solar transm~ttor and the
heat absorber, but not the heat storage function. A generally
accepted definition of a "solar window" or "solar transmittor"
is a membe~ (planar or curvilinear) which transmits solar
energy radiation (0.3 to 2.5 micron wavelength) and in addition
provides some degree of heat insulation, where the heat transfer
loss would consist of heat energy radiation (about 4.0 to 3Q.0
micron wave length), conduction and/or convection. Thus, an
open hole is not a solar window or transmittor by this
definition because it does not afford any insulating qualities.
Similarly, the absorbin~ function is generally defined
as the conversion of solar radiation energy to heat energy. The
dark o~ black portion of tubes 18, herein~efore referred to,
serves this absorbing function. To some extent, the water
itself ~an also do this provided the front of the tube is
transparent. Thus, it should not be apparent that this
invention discloses a unique feature whereby the tube members
18 function as a part of the traditional "collector" structure
and also function as the absorber and storage structure.
It should be noted that the parallel tubes 18 may
be filled with a variety of materials other than water, as for
example, paraffin, asphaltic compounds, eutectic salts, or
granular solids such as rocks. In fact, most any material
would serve the purpose so long as i`t possesses the
pc/,~
` ` 1168g4~
characteristics of being able to absorb heat, store this heat,
and then release this heat when the ambient ai`r temperature
around the tube is lower than the temperature of the exterior
tube surface.
I-n the illustrated embodiment, a se~ment of the
translucent tube surface is colored black along its entire
length in order that this portion may act as a heat absorber.
When placed into position, tubes 18 snould be oriented so that
the black portion is generally perpendicular to the plane of
the solar rays passing through the transmittor panel 11. Though
the illustrated embodiment discloses the transmittor panel 11
as being planar, it may desirably be configured in a convex
curvilinear shape notwithstanding which shape the transmittor
panel takes, whether planar or curvilinear the tubes 18 should
be positioned relatively close to the solar window and to each
other.
The tubes 18 may be oriented so that the black sectors
or portions are at the rear of the tube; i.e. furthest away from
the interior of transmittor panel 11 as shown in ~ig. 1, or
alternatively, the tubes may be oriented so that the black
sectors are at the front of the tube; i.e. closest to the
interior of panel 11.
If the tube is oriented with the black sector at
the rear, solar energy will pass through the translucent portion
of the tube then in part be absorbed by the water and the
remaining solar energy will pass through the water and strike
the black sector 9 which then becomes heated and conducts this
heat into the water. If the tube is oriented w~th the black
-- 10 --
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C'
`-; ` 1 1~894 1
sector at the front, that is, immediately adjacent the interior
of transmittor panel 11, the solar rays will heat that po~tion
directly, and thus conduct the heat i~nto the water. Accordingly,
in either orientation, the water within the tubes becomes heated.
` In the event tubes 18 contain rock or other granular
material whose physical state does not change with temperature,
it is preferable that the surfaces of such granular material be
of a dark, heat absorbing color and the tubes be of energy
transparent construction. If suGh coloring of the granular
surface does not occur naturally, then a suitable black paint or
other black coloring may be applied in order to enhance the
heat absorbing qualitieæ of such material. It should also be
noted that where a granular type of absorber material is employed
within tubes 18, suitable perforations at the bottom and top
of each tube are necessary in order to extract the heat from
, ~ .
within the tube. Tubes 18 should in all cases preferably be
enclosed at their tops.
Referring again to Fig. 1, in operation, solar rays
pass through the solar window or transmittor panel 11 and in-
teract with the black sector of tube 18 as hereinbefore described.In this heating mode, the heat~storing material ~ithin tube 18
(water, paraffin, etc.) will have its temperature raised so
long as a thermal gradient is present whereby the temperature
of the black sector Qf tube 18 is maintained at a higher level
than the temperature of the material absorbing the heat conducted
to it from the black portion.
In the case of employing a granular or other internal
absorber material, tube members 18 are left entirely energy
pc/~
9 4 1
transparent, this is, with no black sector thereon since the
darkened granular or other surface itself behayes as the
principal energy absorber.
When the solar rays get out of position or out of
range and no longer provide sufficient energy input to the
black tube portion in order to maintain the required heat flow
into the absorbing material, the solar window or transmittor
panel should have ;ts energy transparent characteristic changed
to that of ~eing energy opaque. This will prevent any out-
migration of heat from within chamber 17 through the transmittorpanel.
This may be acc~mplished in a variety of ways. For
example, referring to Fig. 2, 3, and 4, there is schematically
illustrated a typical solar window and transmi`ttor panel 11
comprised of a rigid rectangular frame 20 with glass fiber
reinforced polyester facing sheets 21 laminated in opposed
relation to each surface thereof. This construction provides
a hollow cell 22 between the facing sheets 12. A suitable
conduit system 24 connects cells 22 with a container 23 of
granular insulation 25 such as polystyrene pellets or the like.
A conventional blawer, schematically shown, operatively connected
to conduit 24 is employed to blow the insulation 25 from
container 23 into cell 22 filling the entire cavity. This
insulates solar window 11, i.e. gives it characteristics of
being energy opaque and thus for all practical puryoses prevents
any heat transfer from within chamber 17. When desired, the
blower action is reversed and insulating pellets 25 are
withdrawn from cell 22 and returned to container 23. By
- 12 -
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" 1 168941
employing this selecti.ve transfer of insulation, solar window
11 may be made energy transparent, i.e. translucent or energy
opaque, i.e. heat insulating, at will~
It should be obvious in light of the foregoing dis-
closure that once material within tube 18 has absorbed
sufficient heat, and the solar window ll is selectively filled
with insulation, the air within cham~er 17 becomes h.eated by
; convection from the tubes. In order to utilize this heat,
suitable connections can be made whereby chamber 17 is connected
to a conventional hot air ducting sys-tem as schemat~cally
illustrated in Fig. 5. A typical fan and other related "hot-air"
system will circulate the ducted air throug~ cham~er 17. In
such an arrangement, the cold air return should ~e located at
the bottom of chamber 17 as illustrated and~the h.ot-air outlet
should be located at the top, as shown. :Tubes 18 with their
abundance of absorbed heat are now at this po;nt in the heat
extraction phase and become a heat source which heats the air
being circulated through chamber 17.
It is also apparent in light of this disclosure that
chamber 17 need not necessarily be connected to an air
distribution system at all. An alternate to this may be
~ ,
"thermal-siphoning" arrangement where large venting ports are
bui~t into the interior wall portions of chamber 17 at the top
and bottom. Though the rate of heat~ extraction would be less
rapid than that of a blower system, it would have the advantage
of not requiring any electrical inputs and would therefore most
logically employ manually controlled vents.
Alternate embodiments of insulating transmittor panel
13 -
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1 168941
11 comprise the use of an extensible i~nsulating drape 3a adapted
to operate on a conventional pair of tracks schematically
illustrated in Figs. 6 and 7. In em~odiment the ~,nsulating drape
may replace the rigid insulating reflective wall portion 13 in
chamber 17. Thus, when the solar device is operating in its
energy absorbing mode, the extensi~le insulati,ng drape is rais,ed
in the front permitting solar rays to act on tubes 18. When
; the heat absorbing mode is concluded, the drape is simply
traversed to the front, thus thermally-insulatîng transmittor
I0 panel 11 and effectively minimizing any heat loss from the
; chamber. ~f desired, the rear drape 30 may be s~ arranged as
to uncover ports in chamber 17 thus permi,tting heated tubes 18
to convect their heat directly into the adjacent room area.
,~ The embodiment shown in Fig. 7 illustrates how
curtain 30 may be adapted to traverse in a horizontal rather
than a vertical plane. It should now ~ecome apparent that a
-, variety of combinations are possible ~y employing the concept
of the insulating curtain with the basic invention.
The arrangement of parts of Fig. 8 illustrates a typical
, 20 roof or attic installation of this invention. As shown in '
transverse section, tubes 18' are placed in a stepped orientation
` under a roof portion 31 wh,ich comprises a sloping solar
transmittor 11' as hereinbefore described. O~viously the means
hereinbefore described may be used for insulating this arrange-
ment of transmittor structure. The various described modes of
; heat extraction, could also be employed to withdraw the heat
from within insulated roof chamber 17'.
Chambers 17' because of their highly insulated nature
- 14 -
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~ -~ 1168941
may be employed as a rePositorY for any waste heat generated
in a building and stored therein until needed. For example, in
domestic applications, the exhaust heat from clothes dryers may
be piped directly into this chamber and thus stored for subse-
quent use.
In the preferred attic version of Figs-. 9 through 12,
the tubes 18' of Fig. 8 are sho~n disposed along the length of
the attic relatively close to the insulation walls 12, 13
(as in Fig. 1~ that form the important~insulated chambers space
of heat control "cocoon" 17l. As in the case of the em~odiment
of Fig. 8, the attic system of Figs. 9-12 com~ines the normally
wast~d hot attic space cf a house with provnn passive solar
system design fundamentals into a unique, lo~ cost,~roof-
integrated, controllable-hybrid passive solar system (i.e. with
simple means for powered or controlled air-flow heat extraction
~. .
from storage and heat distribution) for space heating and, aIso,
year-round domestic hot water preheating. Such a controllable
passive system achieves the controllability offered by active
` systems and the simplicity, reliability and reduced incremental
costs of passive systems.
.~
Thus, as in the other embodiments, solar energy is
admitted through the sloping roof transmittor glazing 11' and
is collected and stored in situ in the vertical water-fiIled
and sealed tubes 18i. The glazing 11' may slope at an acute
angle of, say, 30 degrees, more or less, depending upon location.
When heat is required, very low powered fans (cool air return
fan 40 in return inlet 41, to the right in Fig. il, and hot
air delivery fan 42 in hot air outlet 43 to the upper left)
,
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1 ~6~9411
direct air over the heat source or heat-exchane
external surfaces oE the tubes 18' in a horizontal path, and
distribute the heated air tc the space to be heated. The fan
distribution motors 40 and 42 may be fractional horsepower,
window-type fans, which are controlled manually or by simple
thermostats, to bring cool return air from the heated room into
the attic where it is directed over the storage tube surface
18', which now act as heat exchangers. The cool air moving
over the tubes extracts the stored heat from the water therein,
and the heated air is distributed by the fans to the spaces
requiring heat.
Further in accordance with the invention, year-round
domestic hot water preheating (DHW) may also be accomplished
by adding two or more pressurized black-painted water storage
tanks 33 in the attic at the base of the vertical solar storage
tubes 18' of Figs. 9-12, and between the conventional hot water
heater inlet 34 and the hot water supply outlet 35. The water
in the tanks 33 is heated by a combination of direct solar
radiation, radiation from the heated tubes 18', and conYection
from the hot air trapped in the attic.
A system of fixed and movable insulated reflectors,
the latter located on the floor at R and the former at the
gable ends of the attic R", may also be employed as in Figs. 9
and 10 to sugment winter solar heat gain, reduce storage losses
at night or on cloudy days, provide an air flow passage for
controlled heat extraction, and reject excess summer heat.
This solar attic concept utilizes the otherwise
wasted space in the structure with a system that has little
,t
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~ ~89~ ~
impact upon the architectural features of the rest of the
building. In addition, this integrated roof system costs less
to build because the glazing 11' functions as the roof surface
as well as the cover Eor the solar collector. Such solar roof
facing glazing 11' as the Kalwall Sun-LiteR Solar Roofing--
lightweight aluminum and fiberglass sandwich roofing panels--has
excellent solar energy transmission (77~) and an insulating
U-value of .46 BTU/hr. ft. F. The flow of energy passing
therethrough next follows one of two paths. The first path is
directly to the row of water-filled heat storage tubes 18'
located below the roof ridge line. Water offers the best heat
storage capacity of common substances, having five times the
heat storage capacity per unit mass of concrete or stone,
reducing drastically the structural requirements for storing
an adequate amount of heat in the attic space. The non-corrosive
low pressure fiberglass tubes 18', covered with an absorbing
coating which converts the sun's energy to heat, as before
described, serve simultaneously as the absorber and storage
elements in the system. This is a proven passive l'water-wall"
which requires no external power or fluid movement for collection
and storage of the sun's energy. The tubes 18' hold this heat
for immediate use or store it for future use at night or on
overcast days.
The second possible path is for the energy to strike
the mirror-like reflector R located on the floor of the attic
in front of the tubes 18', Figs. 10 and 12. This reflector R
serves several purposes. First, it augments the solar gain of
the storage tubes 18' in the winter by reflecting solar energy
- 17 -
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1 ~6~9a~
to the tubes that would not stri]ce them otherwise, as shown by
the lower ray in Fig. 12. As the sun's altitude angle becomes
greàter in the spring and su~er, (as illustrated by the dash-
line rays) the reflector reflects increasingly greater amounts
of unneeded solar energy from the attic. This automatically
prevents excessive heat buildup in the attic during those months
when little or no space heating is required.
In accordance with a preferred embodiment of the
invention, the reflector R is preferably made movable and
insulated, and provides a means Eor reducing heat losses from
storage at night to a minimum, as will now be explained, and
with the entire reflector assembly permanently protected inside
the attic from the effects of wind and weather. The reflector
R, which may be segmented if desired, may be moved manually or
automatically using a simple torque-motor and pulley
arrangement P, Figs. 10 and 12 or a winch and pulley chain and
sprocket drive or the like, from the floor where it is
horizontal or near-horizontal, into a near vertical position R'
in front of the tubes 18', gasket-sealed around its perimeter
to prevent infiltration heat loss. This creates a closed air
channel through which the distributed air is forced a-t higher
velocities over the tubes 18', thereby increasiny heat transfer
and overall system efficiency. The rear of the air channel
is formed by the highly insulated, vertical partition 13
(similar to that of Fig. 1) on the north side of the tubes 18'.
This partition 13 also prevents heat loss from storage to the
unheated northern portion of the attic, and a supplemental
infra-red heat transfer baffle 39 may also be interposed as
- 18 -
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1 1 68941
shown in Fig. 10.
The above-described distribution system may operate
in two modes. Dur~ng the day when sufficient heat is available,
the before-mentioned fans direct the cool room return air
across the heated tu~es in a horizontal pattern extracting heat
from the tubes and distributing the heated aIr to the space
requiring heat. At night or on overcast days, on the other hand,
the movable section of the reflective floor R immediately in
front of the tubes, is raised into position creating an
insulated channel through which the distribution air flows.
When there is no air flow, this insulated section creates a
"thermos-bottle" effect, cutting down the heat loss to the
outside air.
Returning, now, to the previously described further
feature of the domestic hot water preheating system, the
uninsulated pressure tanks 33 filled with water are shown
located at the base of the tubes 18' and are behind the
insulated reflector when in its raised position R', as more
particularly shown in Fig. 10. The tanks 33 may also be
vertically oriented, as between the tubes 18' and might also
be disposed horizontally above the tubes 18' within the
insulation cocoon. The water in the tanks 33 is heated during
the day by direct radiation from the sun and by convection
from the hot air in the attic. The tanks will never freeze
under normal operating conditions because of the thermal mass
of the nearby storage tubes 18' and the tanks themselves,
allowing year-round operation. The tanks are simply plumhed
in series to the inlet side of the conventional hot water
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1 168g41
tank, between the inlet and the water supply. No a~ditional
pumps or valves are required because the pressure of the water
supply is sufficient to operate the system.
The attic may also be equipped w~th an infiltration
proof exhaust fan system, not shown, for those infrequent
times of the year when additional attic venting is required.
As before explained, the attic embodiment of the
invention may also be supplemented by a s;de wall solar furnace,
such as that of Fig. 1, as is also illustrated in Figs. ~ and
10 on the lower floor. Only a small part of such wall will be
required for direct supplemental heatiny of the downstairs
room, the installation comprising vertical glazing t~ansmittor
wall 11, a small number of vertical storage tubes 18 within
the chamber that is insulated at 13, and, an off-peak
electrical heater boosting element 7. This concept thus
enables a minimum area of south wall to be required for solar
heating and puts the principal solar installation in the least
valuable attic space.
The performance graph of Fig. 13, plotting months
along the abscissa and required and supplied hea~ ~in the New
England area) along the ordinate in units of millions of BTU's
per month, demonstrates the remarkable efficacy of the invention
and it superiority over conventional active air solar systems
previously discussed. For purposes of comparison, the best
state-of-the-art active system embodying roof-mounted hot air
collectors with remote rock bed storage and separate heat
exchange coil, storage tank, circulating pump and plumbing
for supplying domestic hot water (DHW), was selected. The
.,, t 20 -
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8 9 ~ ~
required heating load ("Space Heating Load") is very
substantially approximated in the October to April period by
the system of Fig. 9 ("Solar Attic-Space Heating Supplied"),
as compared with the previous active systems of equal cost
("Active System Space Heating Supplied"). These performance
curves clearly show that the solar attic system of the
invention supplies substantially more of the building's space
heating load than do egual cost active systems. The "Solar
Attic DHW Supplied" feature does somewhat better than active
systems ("Active System DHW Supplied") in fulfilling part of
the total "Domestic Hot Water (~DHW) H~eating Load" in the fall,
winter and early sprin~ months. The improved performance of
the invention results from the multiple use of the system
components for several functions and the synergistic effect of
utilization with the hot water system within the insulated
cocoon. This comparison was based on a residential application
having 5621 heating degree-days per year, a floor area of 16~0
square feet, a building heat loss of 5400 BTU/degree-day, and
a domestic hot water requirement of 55 gallons/day. The solar
attic system of Fig. 9 embodied 934 square feet of solar roof
glazing 11' and 96 square feet of south wall glazing 11 (18%
of the south wall area).
The performance superiority of th~ invention resides,
in summary, in the following features:
1. Conventional present-day active systems are
considerably more expensive per square foot of collector.
2. The conventional systems require the use of two
independent systems; one ~or space heating and one for domestic
hot water heating.
- 21 -
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1 16~9~ ~
3. The active system is mounted on the roof, requiriny
expensive mounting hardware. The system of the invention
utilizes roof and wall glazing panels which form an integral
part of the building envelope, allowing a substant;`al cost
deduction for the roof and wall areas they replace.
4. The conventional system requires extensiye piping
and duct-work, resulting in duct and pipe heat losses and in
the use of large expensive electric blowers to overcome duct
pressure losses.
5. The system of the invention achieves cost-
effectiveness by making multi.ple use of major system components
such as:
- Solar Glazing (.collector glazing, roof surface,
weatherwall3.
- Storage Tubes (absorber surfaces, heat storage for
space heating, heat storage for domestic hot water heating,
storage for off-peak electric heat, and heat exchange surfaces).
- Shutter (movable reflector, heat storage insulated
"cocoon" chamber).
6. The above performance comparison is made on a
"first-cost" or initial cost basis. In addition to the system
of the invention, with its low power air fans using
substantially less electricity than the state-of-the-art active
system, the invention employs considerably fewer moving parts;
and therefore has substantially reduced maintenance and repair
costs, compared to active systems.
While the invention has been described in connection
with preferred constructional elements, clearly variations
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pc/ ~ ~ ~
1 ~6894 1
can be made.
It should be further noted that in industrial and
commerical buildings, large cement columns, if suitably
encased within an insulated chamber with a solar window, may
represent a viable substitute for tubes 18 filled with heat
absorbing material.
Though the tube orientations have been disclosed
being substantially vertical, moreover, it is to be understood
that various positions including horizontal are also envisioned
within the scope of this invention.
Various other modifications are contemplated and may
obviously be resorted to by those skilled in the art without
departing from the spirit and scope of this invention as defined
by the appended claims.
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