tag:blogger.com,1999:blog-5019396406912836651.post8338527458300173288..comments2024-03-03T01:34:33.878-06:00Comments on THE ROOF FORUM: How a Roof Turbine Works (or doesn't)The Roof Forumhttp://www.blogger.com/profile/11726271992138210215noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-5019396406912836651.post-90545568924060604902017-05-17T05:45:41.448-05:002017-05-17T05:45:41.448-05:00How interesting, If the flowing water above your r...How interesting, If the flowing water above your roof is spinning the hot watering your underwater attic cannot get out as fast because of the pressure of the flow of water over the roof. See Details: http://www.liquidrubberroofing.comSophiahttps://www.blogger.com/profile/16596935238666146465noreply@blogger.comtag:blogger.com,1999:blog-5019396406912836651.post-76137862516927515552017-04-24T21:49:19.593-05:002017-04-24T21:49:19.593-05:00Swirl your finger around a drain and watch how muc...Swirl your finger around a drain and watch how much faster the water exits a basin compared to naturally under it's own weight.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-5019396406912836651.post-44718833093471058922017-03-26T11:24:39.721-05:002017-03-26T11:24:39.721-05:00The turbine still acts as a static vent in my mind...The turbine still acts as a static vent in my mind. There is a Bernoulli created downwind side. The purpose of the turbine , in my mind, is to reduce the resistance caused by a stationary bonnet or cap. Without exhaust the pressure in the attic increases as it heats up. The exhaust provides for pressure relief but when coupled with intake vents a venturi is created removing heat and humidity. The turbine manufacturers claim the spinning head creates more pull but I cannot fathom that in my head. Spinning is a function of wind, not the other way around. The manufactures<br /> even produce numbers unlike net free area (NFA) for calculation the amount of ventilation needed and CFM for active ventilation.The Roof Forumhttps://www.blogger.com/profile/11726271992138210215noreply@blogger.comtag:blogger.com,1999:blog-5019396406912836651.post-67024928728782153822017-03-26T06:38:57.413-05:002017-03-26T06:38:57.413-05:00Jon, say I set up a freewheeling (not connected to...Jon, say I set up a freewheeling (not connected to a motor) fan outside in the wind. The fan will start turning, but that does not mean that this rotating fan, which is powered by the wind from behind, is also now blowing the wind in front. Actually the wind velocity will be lower after passing through the fan because some wind kinetic energy is used to turn the fan. Doesn't this apply to an unpowered roof turbine also? <br />1.) With a hot attic and no wind, the expanded attic air is at higher pressure than outside air. Put a hole in the roof and the hot high pressure air will move outside to equilize pressure. Put a roof turbine on that hole, it starts spinning, but it is blocking the flow of air to the outside, not speeding it up. If it did, then it's as if you had some sort of a perpetual motion machine. <br />2.) On a windy day, the same logic applies. The wind passing over an open, unobstructed hole in the roof would result in lower pressure outside the roof hole. Air inside the attic would move to lower pressure through the hole. With a turbine, the wind spins the turbine fan but that does not result in lower pressure. The turbine is actually blocking air from escaping, wasting the wind's kinetic energy to turn the turbine. Therefore, with no other concerns such as rain, mice, rats, bats, insects, etc, a simple unobstructed hole would be best. Conclusion, roof turbines put on a good show, but that's all. In other words, since we do have to be concerned with rain, etc, then a turbine that no longer rotates is just as effective as when it rotates.JGastonhttps://www.blogger.com/profile/17880857118420286453noreply@blogger.comtag:blogger.com,1999:blog-5019396406912836651.post-7183058507314382372016-08-15T15:39:10.855-05:002016-08-15T15:39:10.855-05:00I have been staring at a bunch if them on the buil...I have been staring at a bunch if them on the building next door and sat with my coffee trying to logically work out how the hell they actually work.. and that is what lead me here.. I can see hot air doing some spinning and even maybe causing it to accelerate to a point..if you look at the blade shape it would fling hot air out..I have noticed on more blustering days they get up to a higher spead so I'm thinking this helps "fling"that hot air out faster..could the cool wind air not cause the hot air to expand thus helping the whole process heat and pressure have a tendancy to be in collusion if I have my rudimentary physics right..?? Chaz LaBrockhttps://www.blogger.com/profile/06030498411865499569noreply@blogger.comtag:blogger.com,1999:blog-5019396406912836651.post-61650718621177440992015-04-10T13:35:10.802-05:002015-04-10T13:35:10.802-05:00WOW Jon- I have to say that you seem to know what ...WOW Jon- I have to say that you seem to know what you're talking about. Although it could be a case of "If you can't dazzle 'em with brilliance then baffle 'em with B.S." Anyway,I have always suspected that roof turbines were a gimmick. Hot air rises, provide an opening up for exhaust and below for intake and let the physics do the work. Joe in INAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-5019396406912836651.post-33239570378822066792014-07-02T13:31:11.173-05:002014-07-02T13:31:11.173-05:00My house has three turbines for attic exhaust and ...My house has three turbines for attic exhaust and they seem to work great. Attic temperature on hot days is reasonable, and in the mornings the temp in attic is same as exterior. Stays very dry in all seasons (live in Wisconsin). Many homes around here now have ridge vents, but I stuck with my turbines when I reroofed because they were working just fine. I can see why people may not like them aesthetically, but I kind of like the hypnotic spin!Anonymousnoreply@blogger.com