solar attic fans

[village dreamer]

is it worth it to have a solar fan installed? will it cool off my garage a little? how long will it last.

[retiredguy123]

I think an attic fan will ventilate and help to lower the temperature in your attic, and may slightly reduce your electric bill. But, I don't think you will notice any difference in the garage temperature.

[Altavia]

Not solar but this works well for exchanging air in the garage

GF-14 Garage Fan Cooling And Ventilation System (https://www.rewci.com/gf-14-garage-cooling-and-ventilation-system.html)

[retiredguy123]

I don't understand how exchanging air in the garage will reduce the temperature. I have a neighbor who installed garage door vents and an exhaust fan. He told me that it didn't do anything, so he just turned it off. I would want a temperature reduction guarantee before paying someone to install this type of system.

[Altavia]

True, it can't drop the temperature lower than outside air. I ran it at night but shut it off in the morning.

Also best to pull the intake air from a shaded area, not off the concrete drive on the south and west side.

Probably more important to have a reflective barrier and insulation above in the attic.

[graciegirl]

No. I haven't EVER heard that a solar fan cools the garage.

[Toymeister]

In terms of air movement, you are better off with an electric fan vice solar.

I have technology in my smart home which collects data on when the fans run and for how long. The common myths are electric fans are expensive or ineffective..

If you need factual details, I can provide those, such as run times, cost of power, the difference between different models, etcetera.

[billethkid]

We have ceiling fans in every room in the house including the garage....they all run 24/7.

Does not reduce garage temperature...maybe hinders how warm it does get. During hottest part of the day the garage is usually between 85-90.

The key is what temp is the air moved into/out of the garage.

[vintageogauge]

We have the attic fan and garage door vents, made only a little difference in the garage during the day but it does pull the hot air out in the evening replacing it with cooler air. I also put the Owens Corning insulation kits on the garage doors, that made a noticeable difference and also eliminated the noise when opening the garage doors.

[Tom C]

We too have an insulated garage door, garage door vents and an exhaust fan that is on a timer (like a bathroom exhaust fan). These were in the house when we purchased. I assumed it was to address the heat generated by cars being operated, then parked in the garage when you get home? Or.. the prior owner had two Teslas, so I thought that the heat generated when charging of those cars may need some ventilation (one dedicated charging circuit is 220V 50 A and the second is 220V 80 A - I’l bet that made the meter spin!).

The idea of running the exhaust fan makes sense to me in the evening, but only if I am going to be out there, otherwise it cools off by morning on it’s own.

[Altavia]

Toymeister, I'd be interested to learn more from you once I'm transplanted.

I use one a WiFi smart plug to control my vented fan. With the app, you can set it to turn on at sundown and off at sunrise. Or of course control it anytime via the app. There are many options, wired or plug-in, I use this one.

Kasa Smart WiFi Plug Lite by TP-Link (2-Pack) -10 Amp & Reliable Wifi Connection, Compact Design, No Hub Required, Works With Alexa Echo & Google Assistant (HS103P2) https://www.amazon.com/dp/B07B8W2KHZ/ref=cm_sw_r_cp_tai_6zBqDbDCE498X

You need a decent wifi signal at that location for it to work.

These are great for things like Xmas lights also.

[Toymeister]

Toymeister, I'd be interested to learn more from you once I'm transplanted.


I'll give you the answer now in three parts:

The hours and time the fans run

The cost of operation and how the fan choice impacts the operate cost

How you can use this data relative to solar fans

I operate the fan by remote bulb thermostat. On at 120 degrees off at 117.

It operated 49 hours in July
34 June
59 May
April to November no operation
30 October
28 September
60 August

The attic temp has a delayed effect. It gets hot after solar noon and cools rapidly with any rainfall. The typical start time is 1:00 pm and runs 3-4 hours, the fan cools it fairly quickly.

[Toymeister]

There are several types of motors, some are efficent, others are not. They vary in cost to manufacture. As you guessed the cheap motors use more electricity. The attic can at Lowe's or the garage fan already mentioned use 372 watts while this fan is designed to be efficient at 110 watts https://www.amazon.com/QuietCool-QC-CL-1500-Original-Classic/dp/B00K0Q7R50/ref=mp_s_a_1_3?keywords=quietcool+attic+fan+1500&qid=1564608074&s=gateway&sr=8-3

The cost difference annually is 7.47 vs. 11.97 current SECO rates, if you operate it as I do.

[Toymeister]

How does this apply to solar?

First, it runs six months that you don't need it.

Second, solar panels which operate the fan, 100% speed (air movement) at 100% Sun but less than 80%at 80% sun or any other sunlight percentage/air movement ratio. So as the peak solar generation hours pass you need your fan but it isn't operating at 100%

Third. solar fans are more expensive

Fourth. Electric fans are cheap to operate

Fitth, Solar fans inflate how much air the move. Think about it solar fan firms claim that a solar fan driven by 20 watts moves as much of more than the most efficient electric fan at five times the wattage.

[village dreamer]

How does this apply to solar?

First, it runs six months that you don't need it.

Second, solar panels which operate the fan, 100% speed (air movement) at 100% Sun but less than 80%at 80% sun or any other percentage/wife movement ratio. So as the peak solar generation hours pass you need your can but it isn't operating at 100%

Third. solar fans are more expensive

Fourth. Electric fans are cheap to operate

Fitth, Solar fans inflate how much air the move. Think about it solar fan firms claim that a solar fan driven by 20 watts moves as much of more than the most efficient electric fan at five times the wattage.

so , as far as a solar fan goes. its not worth it. that was what I was thinking.

[rjm1cc]

is it worth it to have a solar fan installed? will it cool off my garage a little? how long will it last.

Probably not.
At any rate you would want to bring into the garage the cooler evening air so skip solar.

Measure the temp in the area and see what happens. I get about 10 degrees hotter in the attic and garage during the day without a fan.

[DAVES]

Cooling effect
Depends on how you feel as opposed to thermometer reading.
Reason is simple. Your body cools based on sweat-water evaporation. Moving air evaporates more sweat so you feel cooler.

Sticking a fan in your garage running on automatic
I would not do it. You/I have all kinds of flammable stuff in the garage. Car, paint, sawdust, to mention a few. A fan introduces more oxygen-remember fanning charcoal, a campfire etc. Properly installed there should be a thermal disconnect.
Simple and cheap. I have a fan that I only run when I am working on something in the garage.

Solar fan
Since as described above my use in minimal I would not see any cost savings. For me a viable system would require the collector plus a battery to store the electricity. So the cost goes up as well as the space required.

A fan and air flow
Think of sucking air out of a coke bottle. Nothing will happen,
You need to allow air to get into the bottle as well as trying to such it out. So you need to install intake vents of some kind.
A fan will be rated at free air flow. Vents are not 100% efficient
so the rated flow is reduced in the real world.

[New Englander]

How does this apply to solar?

First, it runs six months that you don't need it.

Second, solar panels which operate the fan, 100% speed (air movement) at 100% Sun but less than 80%at 80% sun or any other sunlight percentage/air movement ratio. So as the peak solar generation hours pass you need your fan but it isn't operating at 100%

Third. solar fans are more expensive

Fourth. Electric fans are cheap to operate

Fitth, Solar fans inflate how much air the move. Think about it solar fan firms claim that a solar fan driven by 20 watts moves as much of more than the most efficient electric fan at five times the wattage.

This is something I never considered. The solar fan will run during the cooler weather because there's no way to stop it.

[xkeowner]

We have a West facing garage. I installed garage door insulation which I believe I purchased at Lowe's but possibly HD. only took a couple hours to install on an oversized door plus a golf cart door and it made a SIGNIFICANT difference in temperature in the garage. I also keep the attic stairs and the window cracked open which creates a natural airflow helping to keep the temperature down at zero recurring expense.

[Altavia]

We have a West facing garage. I installed garage door insulation which I believe I purchased at Lowe's but possibly HD. only took a couple hours to install on an oversized door plus a golf cart door and it made a SIGNIFICANT difference in temperature in the garage. I also keep the attic stairs and the window cracked open which creates a natural airflow helping to keep the temperature down at zero recurring expense.

Kindly suggest to be careful leaving an unprotected opening in the garage ceiling, if there is a fire, that provides a direct path for flames into the attic.

Same for ventilation fans, they should have a fire damper that automatically closes in the presence of flames. An example:

Access Denied (https://www.homedepot.com/p/850-CFM-Electric-Garage-Exhaust-Fan-GF-14/302884447)

[retiredguy123]

We have a West facing garage. I installed garage door insulation which I believe I purchased at Lowe's but possibly HD. only took a couple hours to install on an oversized door plus a golf cart door and it made a SIGNIFICANT difference in temperature in the garage. I also keep the attic stairs and the window cracked open which creates a natural airflow helping to keep the temperature down at zero recurring expense.
What do you mean by a significant difference in temperature? I have a West facing garage, with no vents, no insulation, no fans, and no shade. The temperature in the garage almost never exceeds about 6 degrees above the outside air temperature. In the morning my garage temperature is less than the outside air temperature. Garage door insulation alone can only slow down the heat transfer, but it cannot change the eventual equilibrium temperature.

[John_W]

I have a horizontal screen sliders on my garage door and since our laundry is in the garage, we found it best to keep the garage door open and the screens closed is cooler than the garage door closed. For a few years I cracked the attic steps opening about 6" and I could feel a steady breeze in the garage by the opening and the garage felt better overall.

However, I have since kept the attic steps opening shut for the last couple of years for two reasons. Termites will usually die quickly in temperatures above 100 degrees, I don't want to give them a place to breed. In a masonry home the wooden trusses are my biggest concern and leaving the attic access open creates a greater chance of any fire in the garage spreading quickly.