Solar Attic Fan

[Squintz]

I just picked up a solar attic fan from Home Depot for $218. I pulled it out of the box it it immediately kicked on. It's partly cloudy here today. When the sun is out the fan really blows. While the sun is hidden it still blows but just not as hard.

What happens when it's sunny in the winter time? Does it still run?

I don't think I want this thing running all year round. I see that it has a quick disconnect but it requires you to get in the attic to unplug it. Some of my initial thoughts are... It's only twice a year that I would have to get in the attic and mess with the power so it's really not the big of a deal. I could just seal off the hole with plastic to prevent a major draft. However, I'm not sure the fan will even come on in the winter. The sun may not be hot enough. And covering the hole may not do much good since I already have a ridge vent. So perhaps simply disconnecting the power in the winter would do just as good.

 

[CollinR]

I would assume there is a temp sensor inside so it won't kick on below 80*F but I have no clue.

You could put a relay in that disconnect so you could remotely shut it off.

 

[gatchel]

If you already have a ridge vent won't it just pull in the outside air from the ridge vent? (Path of least resistance...)

You may have to block the ridge so that the soffit vents work more efficiently.

As far as disabling it in the winter a few of the ones I have seen have temp sensors or add on temp sensors that can be used. I wouldn't block it with plastic because it will still spin and cause added wear on the bearings in the fan. You could always just solder into one of the disconnect wires and run it to a controlled relay on an Elk or toggle switch or something...


This one here has an add on thermostat.

http://www.bigfrogmountain.com/solaratticfandetails.html


Check the manufacturer.

 

[JohnWPB]

Why not just put a power flash module in-line to the power for the fan (Using is just as a standard relay). Then you can use Homeseer to control it based on temperature. When the temp drops below... say 80... turn the power flash module off.

 

[mdiehl]

I just picked up a solar attic fan from Home Depot for $218. I pulled it out of the box it it immediately kicked on. It's partly cloudy here today. When the sun is out the fan really blows. While the sun is hidden it still blows but just not as hard.

What happens when it's sunny in the winter time? Does it still run?

I don't think I want this thing running all year round. I see that it has a quick disconnect but it requires you to get in the attic to unplug it. Some of my initial thoughts are... It's only twice a year that I would have to get in the attic and mess with the power so it's really not the big of a deal. I could just seal off the hole with plastic to prevent a major draft. However, I'm not sure the fan will even come on in the winter. The sun may not be hot enough. And covering the hole may not do much good since I already have a ridge vent. So perhaps simply disconnecting the power in the winter would do just as good.

Solar panels do just fine in the Winter. Actually with the clearer skies (less moisture or haze), the panel output will be greater than the average in Summer, just less operating time due to shorter daylight. Panel voltage will also be higher at the lower temps.

Shop around at the local hardware store and find a small mechanical thermostat that you can wire into one of the panel wires to the fan, that will make sure the fan does not receive power when the temp is below whatever threshold you set it to.

 

[Rupp]

What's wrong with it running in the winter? It will circulate damp / stale air and it's not costing you any money to run right?

 

[wuench]

I think you want proper air circulation in the winter time, otherwise you risk ice damns forming. If you block vents or otherwise prevent the heat from escaping the top of your roof will heat up and melt snow, it will then re-freeze when it reaches the lower parts of your roof. Proper circulation keeps the roof temperature in equilibrium.

So the more circulation the better, even in the winter.

 

[SteveQ]

Squintz,

You did not mention if your are replacing an existing roof vent, or if this will be a new vent. If you are replacing an existing vent, you should not cover the opening in winter because your attic space needs the ventilation. If you did not have any problems with Ice dams or snow melt with the old vent then you will probably not have any issue with the solar powered vent being shut off for the winter. I agree with adding a relay or manual switch so you can shut it off in the winter. I think shutting it off will extend the life of the fan. However, I am not sure about the impact of sunshine on a solar panel if no current is flowing. Perhaps this will shorten the life of the solar panel? And, it would be a shame to waste this free energy! Another alternative is to go up on the roof and cover the solar panel with a piece of opaque plastic; this would prevent the fan from running and possibly protect the solar panel from sun/ice/snow damage.

It sure would be nice if you could use the solar panel in winter to power something else in your house!

Steve Q