Active Solar Air Heating

By: Mitchell French

Objective

• Give the class enough knowledge to make intelligent decisions regarding this heating system

Collection

• Solar Collectors Gather heat

• Air is the absorbing fluid

• Air moves directly into house or stores in rock storage bin

• Air circulated through house using ducts

• If excess heated air, stored in container

• If not enough heat, backup heating system activates (traditional system)

Panels

• Must be pointed towards true south– Point where sun is at its highest

• This usually equates to your latitude +15°

• Leniency of about 20°

• Should not be placed in shaded area

• Do not have to be placed on roof

Distribution

• Fans move air through ducts in house

• Large ducts allow the air to move slower and therefore feel warmer

• An “Air Handler” decides where the air will go– From collectors to house– From collectors to storage

container– From storage container to house

Ducts

• Large due to lower temperature of air

• Must move more air to make up for lower temperature

• Must maximize the efficiency of fans

• Requires insulation so no heat is lost (R-16)

• Average system moves air at a speed of 1.5 to 3 m/s

Storage Container Build

• Lined with rocks on the bottom to absorb heat

• Quartz most common type of stone

• Larger than required for fluid system

• Can be stored inside, basement, or underground outside

Storage Container System

• Heated air enters through plenum at top

• Rocks absorb heat from air

• Air enters through bottom, heats as it rises and gets distributed to house

• If air going to house:– Enters through bottom plenum– Absorbs heat as it rises– Fans circulate air through house

Properties of Container

• Materials: Cinderblock, Concrete, Wood

• Must be sealed to preserve efficiency

• Usually installed in crawlspaces or basements

• Should have ½ to 1 ft3 for every ft2 of collector

• Should be 5 to 7 feet deep• Temperature: top-140°F (60 °C)

bottom-70°F (21.1°C)

Advantages / Disadvantages

• Advantages:– If there is a leak in the system, it is

less important than if one occurs in a liquid system

– More effective during the day than the liquid system

– Can heat air earlier and later in the day

– Air systems do not freeze like is possibly with liquid systems

• Disadvantages– Much more space required

Maintenance

• Check ducts for leaks that could reduce performance

• Make sure collectors are clear

• Clean air filters for more efficient flow of air

• Lubricate pumps and fans

• Empty Storage Bin in summer

Installation

• Depends on Container location

• Hard to upgrade existing house

• Must plan to use air solar heating from beginning

Partial Systems

• No storage container

• Collector panels not as large

• Collector Panels placed directly on wall

• Same principle as full system, but no storage

• Collectors are relatively small

• Simpler to install – fits in existing window

Conclusion

• Size makes it cumbersome

• Requires precise installation

References

• http://www.healthgoods.com/Education/Energy_Information/Renewable_Energy/heating_with_active_solar.htm

• http://www.newenergy.org/sesci/publications/pamphlets/active.html

• http://www.solarenergysociety.ca/2003/active.asp• http://www.canren.gc.ca/programs/index.asp?CaI

D=60&PgID=141• http://bathrooms.bobvila.com/Article/743.html

Diagram