Attic Ventilation Project with potential addition of solar attic fan (gable/peak)

[doohic]

The first image is the aerial view of my house. You can see I only have two roof vents (I believe way under vented for my roof). The second picture is the style soffit I have. I do not have gable vents on either end (you can see obviously on the south end I do not have one)

[doohic]

Some great little videos..

http://roofingcontractorreview.com/R...ttic-Fans.html

http://roofingcontractorreview.com/R...e-Venting.html

It appears to me that this website has some good information with some experiments to back it up.

http://roofingcontractorreview.com/R...ntilation.html

[solarvic]

There is a ceiling vent fan that vents out your attic everynight. I first saw it on This old house program on PBS tv channel. The brand is Tamarack. I am thinking of putting one in my house. If you do a google you can find it. You can buy it directly from the manufacturer. There is a youtube movie that shows how to install one. Vic

[doohic]

thanks vic, I'm off to look for that and check out the video. I just got done watching this company's video on their own ridge vent:

http://www.youtube.com/watch?v=beQoz4s7QTc

I think the key in this experiment, is in the baffle, or the dam, that prevents wind coming up the roof directly into the ridge vent, in their design it hits the baffle and is pushed up, which creates the low pressure in the ridge vent, pulling out the hot air.

The other units he uses as comparison have no baffle and the air from the fan is just pushing itself in the ridge vent and out the soffit.

[russ]

The Roofing Contractor site is a good one!

You have to make it possible for air to move up through the attic to the vent. Somewhere there has to be an inlet at a slightly lower elevation.

Hot air rises - law of science! Providing there is somewhere for it to go - meaning vents at the proper locations.

The night cooling is good for an area with cooler night time temperatures. İt can be used for the attic and possibly the whole house.

The big key is good insulation though. The kind people have heard of without the made up names! Made up names only allow for fancy prices and claims. The testimonials are meaningless - you can get them for a dime a dozen (probably less if outsourced to İndia).

A natural draft through the house is wonderful. İ live in a hot area and with the assist of a small sea breeze air moves up through the house (4 floors) and out with no assistance. İn a new design this should be carefully considered.

[mike95490]

I don't have the photo anymore (that I know of) but I've mounted a $15 20" box fan, into the access hatch for the attic. I set it so it sucks air out of the house, and blows it into the attic, pressurising the attic, and forcing air out the attic gable vents. When run at night, it sucks cool air in the bedroom window you have open, and cools the house and attic down.

[doohic]

yeah, i really like the cooling chimney effects, either it be a whole house fan or using a box fan, for my location during the summer (Orlando FL) It's not really an option. Were talking 80+ temps all day all night.

So for me, the house fan is not on my plate. Like I said, my first step is making sure all of my soffit vents are clear and that I have all of my soffit chutes.

My next biggest dilemma is what venting options to go with. I realize that gable vents are not the most efficient, but I've seen proof they will work passively. Until this week I was not really considering the ridge vent, now I am considering something like the venturivent, or similar with the baffle set-up.

Another consideration was using dormer vents, although, from the construction I've seen may not work great in a highwind/hurricane situation. I could also try and track down the style vents that are currently on my house (have not been able to find them yet)

And why I really started talking about this here.... potentiall doing a DIY solar attic vent, similar to the store bought one's, but I'd like to modify/build my own kit. If I go this route, the best idea I have had so far is to mount one attic vent near the center/middle of the roof and have that pull cool air from my soffits to push out the hot air. If I do this I would like to run the numbers on this and really come up with a good plan. I would want to leave this a 12v system (don't want to tie into the house/110), have a fan run off a battery and keep the battery charged using PV(s). I would also like this to be on a thermostat. Battery back-up would be key for me, here in the summer, the attic is still screaming hot even at night.

[dwh]

I have personally installed these on a couple of houses, and they do a good job. They are made so that a second 10w panel can be added, and they really pump with two PVs, but they do a good job with just the single included panel.

http://www.homedepot.com/h_d1/N-5yc1...atalogId=10053

If it were me, I would probably install a pair of gable end vents such as:

http://www.homedepot.com/Building-Ma...atalogId=10053

And then install the above solar attic fans behind them. The only issue is that the vent has to be blocked off around the fan housing to prevent air blowing back into the attic around the outside of the fan housing.

I don't know what effect your existing roof vents would have on such a setup. Depending on the diameter of the existing vents, you might be able to just mount the solar power fans underneath them and exhaust the attic through the existing vents.

[n3qik]

I would check around before doing a continues ridge vent. During a hurricane/high wind event. Water may be pushed up the roof and into the ridge vent opening. This could cause a lot of water damaged.


I have seen snow pushed up and into the attic with building using ridge vents.

[russ]

İ remember hurricane Hugo 10 years back - forced rain through the vent in a gable end of the house in Charlotte, NC.

İt was raining flat!