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Can there be to many types of ventilation?
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[#1] Posted: 07/27/2009 - 10:36:00 AM		Reply with Quote
Just curious if having multiple venting systems on the same roof is beneficial. This roof had soffit and ridge vents, turbine vents, and fan assisted gable vent. Is there a point of diminishing return with to many systems working at the same time, or will they all compliment each other?
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Can there be to many types of ventilation?
 [#2] Posted: 07/27/2009 - 11:04:22 AM		Reply with Quote
Most likely the original wasn't functioning well so someone added another, this didn't help so they added another. This is wrong. Mixing vent systems has consequences, usually bad. One attic space should have one vent system, one roof system with multiple attics each with a different system would be OK and may even be preferable given the right circumstances.

Tom
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Can there be to many types of ventilation?
 [#3] Posted: 07/27/2009 - 11:05:37 AM		Reply with Quote
Yes, you can have too many different types of ventilation that do not work well together. In a well designed system, the natural convection currents formed when warm air escapes out the top near the ridge will pull in cooler air at the soffitt vents. With competing types of ventilation near the ridge, air will tend to be pulled in via the path of least resistance. For example, the power gable vent will pull air in from the turbine or ridge vent rather than at the soffitt line. In effect, you're short-circuiting proper airflow from lower in the attic and you will have some dead air space.
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Can there be to many types of ventilation?
 [#4] Posted: 07/27/2009 - 11:10:15 AM		Reply with Quote
Quote: Originally posted by tnpappas

Just curious if having multiple venting systems on the same roof is beneficial. This roof had soffit and ridge vents, turbine vents, and fan assisted gable vent. Is there a point of diminishing return with to many systems working at the same time, or will they all compliment each other?


Soffit and ridge vents are all that are needed. The turbine and power vents in some scenarios could actually interfere with the flow of air through the attic when ridge vents are installed.

The gable power vent would actually be sucking air in through the ridge, turbine and soffit vents. I can't really think of any positive outcome with this type of venting. The air flow should start at the soffit and exit out the highest point which should be the ridge vents.
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Can there be to many types of ventilation?
 [#5] Posted: 07/27/2009 - 12:46:35 PM		Reply with Quote
The guy that put in all of those systems probably wears both belt and suspenders on his pants.

OT - OF!!!

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Can there be to many types of ventilation?
 [#6] Posted: 08/02/2009 - 12:00:28 PM		Reply with Quote
Mixed ventilation types can also void the shingle warranties.
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Can there be to many types of ventilation?
 [#7] Posted: 08/05/2009 - 8:21:20 PM		Reply with Quote
In regards to passive venting of an attic, I've never seen problems from too much. I'd be interested if anyone can produce a published, independent study on such an installation.
Eric Barker
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