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