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Summary: If your attic is extremely hot you can think of an attic fan. Solar attic fans are available. They are particularly fine on sunny days. But then the attic fans that are solar powered are unworkable after sun set or on cloudy days. But then the attic does have hot air even when the sun begins to set.
Question: My attic space becomes extremely hot. Recently I saw an ad for a solar-powered attic fan. If I go for it, I can remove the heat and at the same time I can also lessen my carbon footprint. Are these fan difficult to install and how well do they work? Will my attic temperature actually reduce? What are the advantages and disadvantages with these fans?
Answer: I wanted to check out the efficacy of attic fans that are solar-powered. So I installed one, which was smoothly done. The installation was carried out early morning when it was still cool. After an hour or so of installation, the solar panel came under the full blaze of the sun. it was really wonderful to see the fans come alive immediately with its blades spinning.
It is a pretty good idea that the sun itself does the job of cooling what it heated. It makes sense. After all the source of your problem is the sun, isn’t it? You also mention of it being environmentally friendly as it reduces your carbon friendly. I am not so sure about this. It depends on the manufacturing process. What if the manufacturing process itself is actually very much carbon positive? But still, it is good that you are choosing solar-powered fan. Overall your reasoning are quite appreciable and sensible.
There are advantages and disadvantages with attic fans that are solar-powered. Of course, the top advantage is that you are actually using freely available energy to power the fan. The fan also does fulfill the function of expelling the hot air. Also you do not need an electrical to fit the solar fans. Solar fans run silently also.
But then after having done the installation of a solar-powered attic fan myself, I know that there are also some disadvantages. The first obviously is that the solar fan depends on solar panel, which requires direct sunlight. The spinning of the fan ceases when a cloud drifts and blocks the sunrays. Even after sun set, my attic remains hot and I am left with a solar fan that does not spin!
At its peak speed when the sun directly shines on to the solar panel, I am able to move a maximum of 800 cubic feet of air every minute (CFM). The spinning of the fan slows does when haze or even a thin cloud moves across cutting off the sun rays partially. The spin is also slow in the early hours of the morning and in the evenings. Consequently the fan moves out less air and slowly too. Over all, the temperature in my attic did not substantially decline. I did take precise measurements to check out the results that I get from the solar fan.
Thousands of CFMs of air have to be moved out continuously to make sure that your attic temperature is reduced considerably. The air has to move out of the attic space to the outside even after sun sets for the residual heat to be removed from roof sheathing, roof framing lumber, attic insulation and roofing materials. The insulation gets heated up in your attic during daytime and the heat holds much after the sunsets.
You should buy a number of solar-powered attic fans if you have indeed decided to go solar. Solar-powered attic fans with a solar panel, which could be kept away from the fan, is suggested. I have a fan with this feature. This feature helped me to locate the solar fan at the rear of my roof just so that this is not visible from the street. I located the solar panel due south on my roof.
Make sure that you do not choose a part of the roof, which could fall where shades of trees could fall. You need to choose a location where direct solar rays fall unhindered from noon till the sun is set. This period is the hottest one, which gives you sufficient solar energy for your fan to spin at its full speed.
A hole has to be cut on the roof for the solar-powered attic fans. If your fan is the one with the feature of remote-panel location then you will have to cut two holes. You should then flash the housings of the fan into the roof shingles properly. If you are unable to do this or are not sure, please get a qualified roofer to do this work. The work is actually easy to accomplish. But then there are some vital steps to be ensured to make your installation leak-proof.
If the installation with the standard asphalt shingles is made correctly, you do not need roofing cement or caulk or any other products for your solar-powered attic fans to ensure that there are no leaks. The right way to keep the rain outdoors is by cutting the shingles and lacing the fan housing into the shingles.
An attic space of 1,800 square feet would require 8,000 CFM of air to be moved. You will then need to install sufficient solar fans to ensure this. Moreover, this amount of air or more is required for the effect of the fan to result in the required cooling benefit. More heat is created by the intense sunlight than are cooled by one or two small fans. The best place for you to learn how to keep attic place cool is to go and see a chicken farm. Tens of thousands of CFM of air is moved by giant fans in these farms to keep alive the chickens.
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