Solar Attic Fan 48-watt - Florida Rated by Natural Light

SUMMARY: It was really hard finding any actual/objective numbers on the temperature decrease from an attic fan installation. Most people would write something like "it definitely FEELS better" but that was too subjective for me. So I created this review with some actual before-and-after numbers so that one can be better informed about a fan's potential temperature reduction. This fan cooled my attic by an average of 6 degrees (may not sound like much of a drop but keep reading for the reasons why). Note that my attic temps, prior to installing the fan, weren't as hot as others have reported (I've read that some people's attics get to 140+ degrees!). I guess my attic's temp wasn't that high after all. The difference between my attic's daily peak temp and the outdoor's peak temp, was in fact lowered after the fan was installed. All of my "geeky" details are below along with before and after temp data I charted.NOTES & MY LEARNINGS FIRST: I live in an 18 year old, two story 3300 SF home with gray, flat CONCRETE tiles on the roof, in Cupertino, CA (zip 95014). My attic's volume is ~1500 SF. Installation was done in July '16 by myself. Fan comes on around 10-11am daily when the attic temp reaches 80 degrees. After sunset, it intermittently cycles for 15 mins every hour until the wee hours of the morning and the attic's temp drops to the 60s overnight. Once the temp drops to 77 degrees, the thermostat no longer has the fan cycle. Relative humidity in our attic ranges from 20% to 30% depending on the time of day. Attic temp peaks between 4-5pm daily (July/Aug). If I keep the attic access door in our hallway open and open up the upstairs windows all day, I can drop the attic's daily peak temperature by another 3 degrees, which is how I know our attic can benefit from more intake vents.Through measuring my attic's temperature hourly throughout the day, I confirmed that my attic remains hot for hours after the sun sets. This may be true for most attics. Here in the Cupertino, we don't have that many days above 95 degrees, but our 2nd story bedrooms can remain hot on the 95+ degrees hottest days until 10pm. In the pictures are the net temperature differences in my attic before and after the fan installation. Before that though, here's what I did to modify my solar fan to continue cooling after sunset...This fan is great, but I wanted more!Natural Light's 36 watt solar attic fan (model SAF36B-FL) doesn't have a feature that I really wanted....a way to have it continue cooling my attic even after the sun goes down. (I thought I'd have to make my own circuitry to do that.) I really like that unique feature of the US Sunlight fans using their optional Solar Control (model #SC20), so I bought both and made some easy wiring modifications to make them work together. I preferred the Natural Light fan due to its high Amazon rating but also wanted the other company's "cool" functionality (see what I did there?) of their Solar Control. It switches between solar power and AC power depending on sunlight availability (after sun sets), has a remote control for the fan (always on or thermostat controlled), and a remote LCD display showing attic temp/humidity. At first, I wasn't sure if they'd work together, but after doing it, I now know it works and I have the best of both worlds...it's now perfect for my needs! =) I'll share how I did it:Re-wire the fan so that the Solar Control acts like a thermostat. Instead of having the red/black wires from the fan's solar panel going straight to the motor, I have them going to the Solar Control instead. The wiring connectors had to be cut and spliced (cut off the spade plugs and solder the wires on to the Solar Control's cables), but that's all it took! 10 mins and done!Here are some things that weren't documented anywhere but I discovered them during my project. They'll help you should you want to do this too:* The Natural Light 35 watt solar attic fan's solar panel's output is 20 volts DC. With full sunlight, the fan motor draws 1.8 amps. (36 watts = 20 VDC x 1.8 amps)* I purposefully bought the bigger model fan (36 watts) since my attic has multiple levels/pockets of air, figuring I'm less likely to have buyer's remorse if the purchased fan is too strong. I can easily slow down the fan speed by covering up a portion of the solar panel. Slowing down the motor by shading a small portion of the solar panel works perfectly.* It turns out that covering up only ~5% of the panel from sunlight results in the fan RPM slowing down to roughly 2/3 speed....perfect if one wants to "dial in" the right amount of attic suction without creating a negative pressure in there. The voltage/current draw is reduced accordingly.* The Solar Control outputs 18 VDC to the fan, so I had a pretty good sense pre-purchase that they'd work together despite US Sunlight telling me that their device works only with their fans (both devices' operating voltages are within acceptable/compatible range of each other). Whether at the full 20 VDC output of the panels or at a reduced voltage, the two work fine together.TEMPERATURE DIFFERENCES BEFORE AND AFTER THE FAN INSTALLATION:I recorded the daily PEAK attic and outside temperatures so that I could see how much the fan is helping. I wanted to know the "baseline" temperature before so that I could justify the cost and effort. Attached is a screen shot of the chart I created, but basically, the fan dropped my attic temperature by an average of 6 degrees on days that had a varied outside temperature of 76 to 91 degrees. I'm happy that the fan helps keep our attic cooler, but I have to say that it would have been hard to know for sure w/out taking before-and-after measurements.I'm concluding that some online reviews of "...house feels cooler..." may contain some wishful thinking (avoiding post purchase cognitive dissonance--there, I used that term I learned way back in college!) Your mileage may vary so don't expect a single fan installation to make your house cooler necessarily. I do not regret buying and installing this fan, because I learned A TON about attics, roofs, temp patterns, etc from the experience.I should note that prior to installing this fan, my attic did not have ANY exhaust vents--a pro roofer discovered this while giving me a fan estimate and told me the builder probably actually forgot! My attic temp drop would be 9 degrees (additional 3 degrees drop) if my attic had adequate intake vents.

The media could not be loaded. This is a *large* fan. And this is exactly what I wanted. Fortunately I have a large roof, so relatively looking, it does not look too large. Installed preliminarily yesterday evening: very little light and very little fan circulation; was a bit anxious how much more powerful it could be. But today noon it is blasting the hot air out of my attic. The sound level is nearly silent; less than 1% of my previous very loud fan. What a relief!! Heard a very, very low noise while meditating in room below attic fan. I will probably insulate between fan and roof to eliminate that sound, but no big deal. I'd most likely get used to it without doing anything. Note on video: this is not my final set-up; wood pieces will be removed. Since I removed my previous fan, the hole and roof preparations were already there. So very simple installation for me. I am going to see if I can get away with turning off my air conditioner, at least more of the time. A bit pricey, but with a 25-year warranty, this seems like a very wise investment. Will definitely save money disconnecting the old fan.I bought the optional themostat and fire safety switch. Doesn't make much sense to not have them installed too. Probably the thermostat should have been included with the fan, if not both items.Update: I noticed today that if I cast a shadow over even a small part of the solar panel the fan slows way down. It appears that the circuitry within the solar panel needs to have continuous light shining everywhere on the panel. I will need to keep leaves, etc. off of it, and I assume that when there are partial shadows on the panel, like from tree branches, that the fan speed will slow down. Need to check on that.Aug 29, 2016 update:I did not like the looks of the solar panel on top of the fan. I *really* didn't like its looks! So I decided to separate them. Now the fan housing looks "normal" on the roof, as does the solar panel directly on the roof, where it should be. Easy extension of wiring under the roof. The angle and position of the solar panel on the roof works perfectly. Repositioning the fan several times created various noise rattles. So I decided to place 1-inch Ethafoam between the roof and the bottom of the fan housing. Unwanted rattling noise stopped. Fan is virtually silent inside the house.Yes, that great 25-year warranty is voided. But just shows you how much I did not like the combined look! Love how it looks now!!Got pine trees, like me? I tried covering the solar panel with a handful of pine needles, and the fan speed slowed down a lot. But with the way pine needles scatter on my roof and slide down the roof, this probably will never be a problem.So, happy camper now.(Note: old video deleted and replace with new video. Amazon allows only 1 video.)

I bought the size larger than was suggested for our square footage. We have 1800' and I bought the unit sized for over 2000. My son and I installed this in about 45 minutes. We are both contractors who have done a lot of building so it was not a big deal to cut the hole and install it. I would suggest cutting the hole as described in the instructions but remove the shingles and put them back by cutting the length as needed. The circle you cut will give you the proper arc in the roofing as you install them around the the new unit. If I wasn't in the business I would have hired a contractor to install this for me, pretty cheap insurance having someone who really know what they are doing install the unit.We love the fan. It's very quiet, I had to go into my attic to see if it was actually working. Buy the the thermostat,you don't need this running year round, you'll just put additional hours on it needlessly. With the thermostat installed, it comes on at 80 degrees and off around 70. The fan runs full speed in direct sun then slows down as the shade hits the panel but it keeps running as long as there is light.Can't say enough good about the fan unit, we are so glad we bought it.Mike(Followup) Inside our house is about 4 degrees cooler, maybe more which is huge when its 100 outside. So glad we bought this. It is very, very quiet. The only way I could tell it was running was by going into the attic and listening. Even then it was whisper quiet but it sure does move the hot air out of my attic. Get the thermostat and just let it hang down in the attic. The fan will come on an 80 in the attic and off when the light from outside is gone or the temp hits 70 in the attic. Great product guys, thanks!!