Never saw this before. House had 2 solar ventilators for the attic. The house already had soffit vents, gable vents, and ridge vents. The same company that installed his reverse-osmosis water filter for $7000 (after an in-home water test on a municipal water system) installed these at $450 each. :shock:
They were nice, however. They run on low speed constantly all year long.
Nice, I have not seen one yet.
According to a seminar I attended last month, these added vents are actually reducing the ventilation in the attic by taking the draft away from the soffit-to-ridge vent and replacing it with the mechanical vent-to-ridge vent thereby only exchanging the air in the peak of the attic instead of the whole attic.
The ridge vent will draw its air from the nearest source.
Exactly, it is similar to adding gable vents to a home that is utilizing soffit and ridge vents. It comes in the gable vent and out the ridge vent bypassing the soffit vents and all the attic area in that direction.
Are you writing this up as a defect?
No. Just sharing with you. I wish I could afford a couple of them.
Conventional electric fans can actually suck conditioned air out of the living space, but these weren’t that powerful.
I read the posts about the possible negative consequences. However, that hasn’t been proven to me. The fans rotate on a very low speed. I tend to think that this added low-speed draw of air through the structure is beneficial. The warm air is at the top of the attic anyway, so whether the make-up air comes from the soffit or ridge, is inconsequential as far as I’m concerned. It was a pretty large attic. I don’t think the draw of these 2 low-speed fans would be enough to cause all the ridge vents to act as intakes.
From what I have studied, air will take the path of least resistance like water and electricity.
Accordingly, an opening 4 feet away from the ridge vent, even if it was designed to draw air out, will serve as a source of air as it is drawn out of the ridge vent by wind blowing over the house.
Should we ignore this until it appears in a code book, or inform our buyer of the concept and allow him to draw his own conclusion?
I plan to. I’m certainly not going to advise someone to remove or plug their ridge vents if a power ventilator is present.
I agree.
Who did the seminar? What are their credentials? How did they make their conclusions–what testing did they perform? Where is the documentation?
Finally, if adding one or two power vents “actually reduces ventilation in the attic”, how many power vents would you have to add to reduce ventilation to zero?
Not unless I see detrimental effects like excessive moisture buildup or such but I do verbalize my thoughts on it to the client, if present.
Jim that Air Vent seminar in St. Louis was good. Most of the home around here are not event right.
You got that right, Ken. I went to the one in Springfield (got my buck knife, too) and it really was an info-packed, fast two-hours.
These guys sell all of the different systems…but take great pains to see that their dealers understand which ones do the best job, and why.
I think Ken would agree with me that anyone who can get a chance to see their seminar (Free…and worth 2 hours of NACHI/ASHI CEUs) should attend.
Still waiting for that scientific study publication link.
I got my buck knife, too. I found the 2hr course to be full if great in formation, I would tell ever one who can attend to take the time.
Stay away from solar attic fans.
POST #5
“Power vents and ridge vents would fight each other. Power vent would suck easiest flow of air. Power vent would suck high from the ridge vent instead of where it is supposed to suck low from the soffitt vents. This would be wasting your time.”
Still waiting on an authoritative source, such as the Energy Dept. or a scientific study. Anyone got that?
P.S. Seminars by folks selling ridge vents do not count as authoritative.
All I got is other opinions mixed with common sense. :mrgreen:
I have first hand experience with this.
I have soffit vents, ridge vents and two power vents near the top of different sections of the attic. The attic is very large, about 4900sf with a 10/12 hip roof. I built the house and designed the attic ventilation this way on purpose. The ridge venting is simply there for exterior architectural effect and backup venting purposes in case the fans quit or it is not hot enough for them to come on.
To summarize a lot of “testing” and experience with the fans on/off or in one case a broken fan on hot days I know very well how this works.
Its one of those things that, yes, there is interaction between having the ridge and power fans both but it is a small percentage. A small fact that can be easily blown out of proportion in building science discussions.
The fact is this, when you have just soffit/ridge venting it meets code but barely vents the attic. (Think about all of those hot attics you go in) When you turn on a power roof fan or two, that hot air is sucked right out!
Since heat rises, all of that really hot air gets sucked right out and the lower attic area is very warm but not hot! I even have a black roof. With good soffit venting very little air is pulled from the living space, again a small percentage.