Originally Posted by
MCHUTZ
Attics here in the southern states (TX, FL, GA, TN, AZ, LA, etc.) are more than hot. Most of us that have spent anytime working in an attic know they are a miserable environment to work in. However, a properly ventilated attic makes life not only better for us HVAC contractors, but also provides a much better living environment for the homes occupants. The keys are to have a trifecta of:
1) Proper insullation
2) Some sort of radiant barrier to minimize solar absorption
3) Good ventilation
We have designed a Solar Powered Attic Fan (Attic Cool 1600) that provides up to 1600 CFM of attic air displacement. When properly sized (1 Unit to every 2300 square feet of attic space) products such as these can achieve 10 air circulations each hour (As required by the home ventilating institute - HVI) to achieve energy efficiency. The KEY to PAV's (Powered Attic Ventilators) working correctly include:
1) Use of a high, quality product. Our Solar Powered AC1600 uses a variable speed, brushless motor that is encased in stainless steel. As such, the product has a 25 year, transferrable warranty. No more motor burn outs every 2 to 3 years. We use a proprietary poly solar panel. Although monocrystalline are generally more efficient, that is not the case for stand alone applications. Polycrystalline panels are remarkable at generating power in low light, cloudy or partially shaded environments. We could not generate the same results with monocrystalline panels. There are numerous other features to the Attic Cool 1600 that make it a great product for solar powered attic ventilation, but there is more to proper attic ventilation than this.
2) You MUST ensure that you have adequate passive or static ventilation in place prior to installing any PAV. The HVI recommends a minimum of one square foot of soffit ventilation for every 300 CFM of displacement by the PAV. We have found this to be a little low, and recommend 2 sqaure feet for every 300 CFM. The worst thing that can happen with PAV installation is to create a negative pressure situation that could draw cool air from your air conditioned living space.
3) The Solar PAV needs to be properly positioned at or near the top of the roof, as far from the majority of the air intakes as possible. It is also important to place the unit away from roof mounted air intakes, such as air hawks, whirly birds, etc. as it may result in drawing the majority of clean air in through the roof mounted vents as opposed to the soffit vents - which are the optimal conduit for new attic air.
The bottomline, as with any HVAC associated product, proper pre-installation inspections and proper installation with skilled technicians generally leads to better results. When used properly, Solar Powered Attic Vents (with intgrated thermostats) can provide years of benefit to the home owner, including:
1) Preservation of attic placed mechanical equipment
2) Preservation of duct work
3) Extending the useful life of the roof and roof decking
4) Better indoor temperature control
All of which add up to both short and long term savings!