Attic turbine question?

[flickit]

I have used these before with excellent results and now want to add one to a detached garage. My main concern is the garage has no eave vents but does have 2 large gable vents. Will this be effective or should I add a few eave vents?

[Unregistered]

What are you trying to vent?

The basic purposes for venting a roof in a HOUSE are to carry off moisture that "leaks" into the attic from household.

A secondary purpose is to help vent out warm air that "leaks" from the household and causes air dams.

Venting the attic in the summer to reduce heat load does not work.

You don't have either of the first 2 in a garage.

And does the garage have a ceiling?

[suemarkp]

Venting the attic in the summer to reduce heat load does not work.

Why not? I've heard anecdotal evidence that power gable vents can reduce the temperature of upstairs rooms because the ceiling now has 100 degree air above it instead of 120 degree air. Passive or even turbine vents may not be as effective as a power vent. Is that what you're trying to say?

[xkvator]

...and causes air dams.
...and then the melted air leaks back down...

Venting the attic in the summer to reduce heat load does not work.
IMO...wrong


You don't have either of the first 2 in a garage.

And does the garage have a ceiling?
no moisture in a garage?...IMO...wrong

[flickit]

Why not? I've heard anecdotal evidence that power gable vents can reduce the temperature of upstairs rooms because the ceiling now has 100 degree air above it instead of 120 degree air. Passive or even turbine vents may not be as effective as a power vent. Is that what you're trying to say?
...is what I am saying but more precisely, I intend to use the passive turbine but do not have any eave vents which as it would seem should provide a better means of airflow through the attic out the turbine since they are lower then the gable vents which I do have but are closer the roof peak.

[mdshunk]

Venting the attic in the summer to reduce heat load does not work.HUH? :confused: :confused:
If you're venting out 100 degree air and substantially replacing it with 80 degree outdoor air, then the heat load in the attic space is reduced almost 20 degrees. This may only equate to a few degrees in the conditioned rooms below, but it is still "free" heat loss. Even the long form Manual 'J' calculation takes into account roof color (which is roughly equivalent to attic temp).

[Wgoodrich]

Air normally moves from west to east or east to west most commonly. Gable vents in those directions where the wind normally comes from will create a cross ventilation flow equal to any output your turbine vent would produce with little gained.

It is commonly understood soffit vents then roof vents at peak of roof work best in all weather conditions concerning heat rises in the soffit then out the peak roof vents like a chimney whether air is moving or not. When sun in baking and air is not moving this is the most efficient method to ease heat conditions in the attic that causes premature wear of roofing, warping of roof decking and much more.

It is my opinion little is gained in venting attic due to heat rising if attic is adequately insulated. I do believe some cooling cost is saved but so little you would seldom notice it unless without any air conditioning in second floor of home. Venting is installed mostly to limit damage caused by the trapped excess heat in that attic as discribed above.

Just my opinion

Wg

[Unregistered]

Exactly.

You need to move LOTS AND LOTS of air through the attic to noticable reduce the AIR temp.

And you still have the hot surface of the underside of the roof radiating IR energy.

Power vents don't don't cool off the attic enough to pay for the power to pay for them.

And if the ceiling/attic interface is not well sealed it can suck expensive conditioned air out of the house.

[flickit]

...indicated they had not taken any data with gable vents only. This seems to indicate a need for soffit vents and herein lies the dilemma as there isn't much of a soffit on the roof ends because of the short distance from the header to the roof rafters. Maybe lowering the gable vents will do the trick, otherwise will hang some insulated flex tubing near the turbine (outlet) and the opposite ends at corners of the attic (inlet).