|
HOME |
Welcome to Linda and Terry Wolff’s
2012 Solar Products Catalog
Specializing in Sustainable Solar and Wind Energy Products to Brighten your Life! |
|
|
 |
|
|
|
|
Solar Air Heating
Pricing and Purchasing
|
|
SOLAR
HOT AIR HEAT INFORMATION |
COMPONENT
DESCRIPTION & PURCHASE INFORMATION |
|
|
|
|
|
AIR COLLECTOR SYSTEMS
Solar air collectors are similar in operation to liquid collectors with
one major exception. Air is circulated through the collector and is the
medium of heat transfer. Since air will not freeze under any normal
circumstances on the planet, all of the techniques and equipment needed to
protect liquid systems can be ignored. Air collectors are being used
successfully today for such diverse applications as composting toilets,
heating water and benzene removal from the earth. Their main functions are
for solar space heating of homes and buildings.
The Collectors
In the late 1970’s, most collectors were of questionable
construction, with efficiencies of 40 to 50%. By 1985, efficiencies had
risen to 60 to 70% and collectors were built with life spans up to fifty
years. All high quality air collectors today have three things in common: an
enclosure made of aluminum or steel, insulation on the back and sides and
low iron, tempered glass glazing on the front. Collectors normally have a
single glazing with a dead air space between the glass and the absorber
plate. Absorber plates are made of aluminum, steel or copper. The plate is
coated on the side facing the sun with black paint or a selective surface
process. Selective surfaces (black chrome) increase efficiency by limiting
reradiated energy back through the glazing. Air collector absorber plates
should be dimpled or corrugated to create air turbulence that helps “wash”
the heat from the plate.
Blowers and Controls
When installed properly a 4 foot x 8 foot air collector can provide
25 to 50% of the energy needed to heat a 400 to 800 square foot space
depending on climate and building construction. This makes air collector
systems ideal for zone type heating systems. We normally use a separate
blower, control and ducting system for every 32 to 64 square feet of
collector area. The blower pulls air from the cold air inlet of the space
through the collector and blows the heated air back to the hot air outlet.
Optimum performance is achieved with a squirrel cage blower of approximately
200 to 400 cubic feet per minute of air flow. Smaller blowers can be used
and performance is slightly effected, but they must be of a squirrel cage
configuration.
The system is controlled by a simple, reliable bi-metal switch in the
collector which turns the blower on at 110° and off at 90°. This gives
automatic operation with each sun cycle. An interior thermostat or manual
switch wired in series with the bi-metal switch allows the occupant to “call
for heat” or shut the system off when heat is not required. The system is
completed with the addition of a backdraft damper in the duct system to
prevent nighttime cooling from thermosyphoning.
Air Movement
Hot air rises and cold air falls. This concept of air movement,
called natural convection, is important in any space heating project no
matter what fuel is used. Wood stoves are superior to fireplaces in heating
mainly because the stove causes a convection current of air throughout the
room or building. Most fireplaces only radiate heat into the immediate area.
Although this concept is ignored in designing many modern fossil fueled
heating systems, it is an integral part of all successful solar heating
installations. If a solar heating system works with natural convection, hot
air rising and cold air falling, then the result in comfort level can exceed
expectations. |
|
|
|
|
The Installation
Almost everyone today only lives in half their house - the bottom
half. We need heat the most when the weather is cold and we are sedentary
(sitting or lying down). In any building with little air movement the air
tends to stagnate or stratify. Air temperature rises approximately 1° F. per
foot. The ceiling of an A-frame house can be 20 to 25° hotter than the
floor. Any good space heating system is designed around the fact that we
live near the floor and the heat is at the ceiling.
The cold air inlet to the heating system is the key to efficiency and
comfort. To heat any given space, the cold air must be removed and
circulated through the heater; therefore, the inlet must be ducted so it is
on or near the floor. If the inlet is placed on the ceiling, the heater will
tend to recalculate the hot air and leave the floor cold. The hot air
supply may be placed at the ceiling or on the floor with little difference
in performance. If placed on the floor, the hot air rises to the ceiling
within a short distance. Since collectors are normally installed on the roof
of the building being heated, it is best to place the hot air outlet in the
ceiling to shorten the duct run. A system installed in this manner
decertifies, or mixes, the air in a building like a ceiling fan, in addition
to supplying solar heat.
Orientation
The orientation of air collectors for heating in the winter is the
same as given on page 18. The collector should face within 30° of true south
and tilt at an angle of latitude plus 15°.
Energy Storage
The main niche for air collectors in the solar industry is supplying
25 to 50% of required energy for space heating. Additional storage is
not required in most cases. A normal, well insulated house has enough
interior mass alone to store enough heat for three to four hours after
sundown, if the temperature is raised 10°F. (i.e., 68° starting, 78°
ending). More massive construction, such as adobe or brick, can store even
more thermal energy. Due to their complexity, large rock and water storage
systems are rarely cost-effective. They often require extraordinary
maintenance.
The best features of air collector systems are simplicity and
reliability. The collectors are relatively simple devices. A well-made
blower can be expected to have a 10 to 20 year life span if properly
maintained, and the controls are extremely reliable. Since air will not
freeze, no heat exchanger is required. By using packaged insulated flex
duct, the installation can be accomplished by anyone with a little
mechanical ability. All this adds up to a quick payback on the cost of the
equipment and gives you years of warmth with safe clean solar heated air. |
|
TOP |
WATER HEATING
WITH AIR COLLECTORS
Air collectors may be used to heat domestic hot water using an air to liquid
heat exchanger which is
much like a car radiator. A small blower flows air through the collector and
passes it over the fins of
the heat exchanger and returns the now cooled air to the collector. A
1/100th horsepower pump draws
water from the bottom of the storage tank and flows it through the copper
tubing in the heat exchanger
and back to the top of the tank. The heat from the solar heated air is
transferred to the water. Although
air collectors are not quite as efficient as liquid collectors in heating
water, the systems are simpler and
require less maintenance than glycol water heaters. An air collector solar
water heater uses the same
type of differential control as a liquid system, but the differential is
usually higher to account for the
lower heat capacity of air. The system must have a backdraft damper to
prevent freezing the heat
exchanger tubing in cold weather. See the diagram |
|
|
|
*Special thanks to our vendor AAA Solar
Supply for use of their diagrams. |
|
TOP |
|
|
|
TOP |
|
All transactions made on this site are secure and Hacker Safe. All Our Payments are processed through PayPal, a trusted company owned and operated by eBay.com.Prices are usually correct but subject to change, if there has been any change we will notify you . |
|
|
|
This page designed and maintained by Terry R. Wolff
Last up-dated on
January 10, 2012
HOME |
Solar Panels |
Solar Power Systems |
Wind Energy |
OutBack Energy Products | Electrical
Supplies | About Us |
Contact Us |
Ordering Info |
Link Resource |
|
