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Question DetailsAsked on 2/10/2017

I have two turbine that are squalling, in atempts to getting them repaired I was told that they should be removed.

Do turbines bring in humidity and cause more issues then good. Should I have them repaired or replaced. I was told that I should have them removed and

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3 Answers


In calm air they are basically little or no different than equivalent open air space box vents or ridge vents. When the wind is blowing with many or most brands you actually get net air INFLOW, not outflow as the wind blows into the the dome from the vanes - which can reduce the ventilation in your attic unless the wind is so strong that you reverse the natural flow and the air coming in the turbines goes out the eave vents - though that will be fighting the tendence of the hot air to rise. This type vent is also susceptible to rain infiltration with most models, as rain or snow blows into the vane openings and runs down into the attic. Some types try to catch the rain on a domed or pointed rain deflector inside and drain it away down the throat of the turbine part and from there drip from the overhanging dome part outside the roof-penetrating duct portion onto the roof, others just let it drain right down into the attic.

This is with respect to the normal ball type turbines - there are a few out there which have "closed" vanes or blades on top or on the side to turn it but that part is NOT connected to the attic - it is just a means for the wind to turn the top. Then inside there is a horizontal fan or spiral which the rotating top part turns - this pulls air up into it from the attic and exhausts the warm air from the roof area. This type can pretty much avoid the rain/snow infiltration issue and move more air - but obviously only when the wind is blowing.

As for letting humidity in - basically if you have proper attic ventilation (with eave vents leading to ridge-area venting of any kind) the outside humid air is getting in at the eaves anyway - so except for the fact many turbines let rain and snow in through the vanes, humidity as such is not something they aggravate. If you look under the turbines in the attic, you will readily see if there is framing staining, matted insulation from getting wet, or staining from pooling of rain/snow infiltration on the attic floor or the top surface of the underlying vapor barrier and/or ceiling drywall.

Bottom line - the biggest flaws of turbines are that even if they worked as advertised to remove hot attic air in the wind (and many do not), typically your hottest periods in the summer and the coldest days in the winter, when you most want to remove heat and humidity, are calm - so the turbine gains nothing in that case. And if it is windy, then natural flow from the eaves to the ridge (or sometimes eave to eave in heavy winds) will provide far more than needed ventilation as long as there is adequate eave to ridge ventilation. Also, because they are quite inefficient at moving air in general, it takes up to about 10-20 of them to provide adequate airflow for a normal size roof - makes for a pretty unattractive roofline.

One other issue is they have a nasty habit of blowing off in heavy winds (leaving a 8-24" hole open to the rain), and of course most brands squeek after a few years - basically the only ones that do not are the pricey jeweled pivot point ones, some of which go a half centruy or more without maintenance or squeeking.

The other big drawback is the attic ventilation should be spread across the entire attic area, not concentrated in just a few rafter bays as it is with box or turbine vents. If you use a smoke pencil in an attic, you can clearly see that the vast majority of the hot air movement is up to and between the rafters, not crossing between them, when you have individual roof vents, so while you may or many not have adequate ventilation in the bay or couple of bays where the vent is, adjacent areas may be excessively hot. I have seen as much as a 50 degree difference between rafter bays in the attic from this effect. Therefore, distributed eave vents (between each pair of rafters at the eave) and ridge area venting in each rafter bay is by far the best solution - and continuous ridge vents are generally the best way to get an adequate amount of ridge venting. [More on ridge vents issues and some commentary on and brands in the Home > Roofing link in Browse Projects, at lower left]. Granted, in some heavy snow areas a central or third-point elevated vents or ventilation cupola coming up off the ridge vent are needed to get ventilation through the snowpack, and in areas with a lot of blowing debris or pollen and such you have to get up there and vacuum or blow out the ridge vents every so many years to prevent blocking, but still a generally better solution than on-roof vents.

If turbine vents are the only attic exhaust you have, then I agree - full-length ridge (or similar for non-ridge sloping roofs) venting is a good idea. As to whether you remove the turbines or not - might be cheaper to replace the bearings and leave them in place if they are not letting rain and snow in than to remove them and patch the roof where they were. I have also seen people replace the turbine dome with a rain and snow resistant furnace rain cap like the following to leave the ventilation but get rid of the thrumming and squeeking -

Answered 3 years ago by LCD


One thing I did not say - have you tried lubricating it - short-term fix that if repeated every year or two might keep it going a decade or more. Some you can reach up into from below with a small container of gun or sewing machine oil to lubricate the top of the bearings well, others you might need a flexible spout old- oilcan to reach up in, or take the dome off from the roof and get at the bearings that way.

For this purpose you want a thin general purpose or gun/sewing machine type oil, coat the bearings or bearing points from the top then spin it around a bunch of times, then wipe off all the excess oil so it does not accumulate dust and gum the works up. Normally some of the oil will seep down into the bearing enough to make it quiet. This will commonly alleviate the noise if from a bearing - if the bearing has totally gone out so the dome wiggles and scrapes against the base duct, then short of replacing the bearing or the unit itself it will squeek forever.

Answered 3 years ago by LCD



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