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I need to further vent heat out of my attic. The gable ends are brick, so I will not be going through there. So, some type of roof mounted venting system. I was looking at electric vents and putting it on a timer vs thermostat. Any suggestions? I was planning on putting one at each end of the house. Any problems with that?
I think a thermostat would better.
I live in Florida. An engineer friend of mine told me the electric fan vents move little air. A single fan blowing into a space moves about the same amount of air as two blowing out. He went further to tell me that roof vent, the long type, were most effective a few inches just below the roof ridge.
It is important to have good air circulation in the attic area. This would be adequate vents in the soffits in tandem with the ridge vents. The correct R value insulation is also a requirement to achieve optimal adequate circulation and temperature.
Well placed shade trees are great pay offs but take awhile to become effective.
This about all I know the subject and this is how I am rigged. I also put in a metal roof and that has helped. I needed a new roof and went metal as I will be dead when it needs replacement.
As an energy save I put in solar hot water about thirty years ago. I would not do it again. Yes it saves money but not enough to pay for itself due to repairs and having to move it when the roof has been replaced twice.
Ridge vent and equivalent area in soffit vents, let convection do it's thing.
I would install some of those wind turbine vents and let them work 24/7 for free.Attachment 296244 They will work with even a small breeze and draw a lot of air out. If they work at night and when you aren't there the roof won't get nearly as hot. You probably should also install soffet vents to let air in when the garage doors are closed. If your garage seals up fairly tight they won't be able to pull out much hot air. I added them to our hip roofed house in Charleston, SC and was amazed at how much they pulled out of the attic and how much our electric bill dropped after they were installed.
They can easily be closed off for winter months if you want.
I have solar powered vents on my roof and very pleased with them. I replaced the small square plastic roof vents (4 was all installed at factory - double wide mobile home) with 2 that required a 13" hole for each. Stand in front of solar panel and block the sun, then wait 10-15 seconds and move and at the same time having hand at edge of vent it was very interesting how the air temperature was so warm in just that brief time without the fan running. You must balance the air flow or it will not work well. Meaning you need to draw cool (relatively speaking) in at the bottom and remove the heated air at the top. If you don't have enough soffit vents or adequate open area to let enough air into the attic, you cannot remove the heat right. Doesn't matter how big or how many of whatever you install for vents at the top, wind powered, solar powered, electric, etc. they can only pull air through the roof that can come in. And it needs to enter low and exit high to allow the heated air to get out.
I was very pleased using thermostatically controlled powered vents for removing summer heat from my attic when I lived in Portland. Prior to venting, during heat spells the R38 insulation would become fully saturated with heat during the day and would take late into the night to dissipate. The hottest time in the house would be late in the evening when one would feel radiating heat from the ceiling. After installing the attic fan this problem was eliminated and we were able to avoid air conditioning. I set the fan to come on about 85 to 90 degrees and it ran until the temp dropped 15 degrees below the cut in setting. On particularly hot days the fan would start about 10 AM and run until 10 PM which is quite a bit longer than one would get from a solar powered unit. The need for two units would depend upon the size of the house and layout. Adequate soffit vents will aid in air flow. The use of these units would greatly reduce the load of an air conditioned home and have advantages over a "whole house" fan. I would provide an on/off switch to shut the unit down when not needed.