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Re: Help with Attic Fans


Thanks for your response. I guess I have to get in my attic somehow, but that's easier said than done. If I can figure out how to post a photo here, I will. Maybe someone can identify what I have on my roof.

asc2078 wrote:

Without a picture or anything specific, it is impossible to tell what you have.

I will say however that if they are properly installed, electric, attic cooling fans, You probably will not have a wall switch in your house to turn them off and on. The fans should be connected to a thermostat switch, located in the attic. They should turn on automatically when the attic gets above a certain temperature.


Re: Help with Attic Fans

Thanks Yuk Yuk ... I'll take a photo and post it - haven't looked at all the options here yet.

I did look at my electric panel and didn't see anything that refers to them. Yes, I'm sure it's 150º in my attic, but it's a moot point because my ladder isn't quite high enough ... though it gets me close enough that I might give it a try - I also know that it's a mess around the trap door with a lot of loose insulation, which is one reason I haven't wanted to try. Every time I open that door this crap falls down on my head.

Not sure what you mean by open eave but there are soffits running along the kitchen and bathroom ceiling (at least that's what I think they are) - the house is sort of a craftman-style bungalow ... small (700 sq. ft.), and it's dark enough that I'm surprised at how hot it gets inside.

I'll post a photo as soon as I can get one taken.

Appreciate everyone's help.

Re: Help with Attic Fans

Okay - so as I was taking photos of the "fans", if that's what they are ... a breeze picked up and I saw them start to spin around - so, now I know something I didn't know before ... but if that's how they're supposed to draw heat out, they don't seem to be working very well.

So here's a photo - this one is on the lower roof over the bedroom - the other one is exactly the same and is on the main roof.

Re: Help with Attic Fans

Besides .... those turbine type are only effective when a wind is blowing.

Re: Help with Attic Fans
Re: Help with Attic Fans
Re: Help with Attic Fans
mtngigi wrote:

Can you elaborate on what you mean by one short-circuiting the other? Doesn't that imply they're electric?

They spin, I know that now because I witnessed it, but I have no way of knowing what's going on in inside of them under the roof and into my attic, and therein lies my dilemma.

If I may offer an thought to that point...

Basically a circuit in this case is the path the air currents flow within the attic.

The methodology here would be to have a source of intake air vents lower down on the roof plane and exhaust vents higher up on the roof.

Since warm air is less dense it rises and cool air is more dense it will settle lower down. The intake vents lower down the roof allows cooler outside air to enter and displaces the warmer air by pushing it upward toward the exhaust vents higher up on the roof.

When this condition is right you end up with convective air currents exchanging the air inside the attic from the warmer air being heated by the sun radiating down on the roof with relatively cooler outside air.

There are two types of ventilation ...

passive .... simple openings or holes

Typically the intake will be passive types with holes or slits for the openings located at the underside of the soffits or the eve of the over hang part of the roof .
However there are homes where the roof doesn't overhang which means there would have to be some other provision for the intake vents.

There are also exhaust vents that are commonly used that are passive. The most common are the gable end vents seen higher up near the peak on the end gables of homes.

Other types of passive exhaust vents are the 1 foot square hoods seen spaced out on the roof higher up . Basically a square hole cut into the roof with a protective covered installed.

The ridge vent is another type located along the outer peak ( ridge ) of the roof. Basically a slot cut into the peak and a protective cover installed that runs along a good portion of the roof

active ..... fans .... electric ( or solar) and wind powered turbines

These types are typically used for the exhaust ..... they tend to move fair amounts of air quicker . In your case the wind turbine type relies on a outside wind to drive them and their performance drops considerably when they are not turning .... basically they are just a passive vent.

So ... how does this relate to a short circuit ?

A short circuit is basically a condition where the intake and exhaust occur within a short distance from each other.
Many things can contribute to this condition which reduces the intended performance of air exchange.

For example ....

If there are more exhaust openings situated higher up than intake vents there can be a condition where the upper exhaust vents will be circulating air only within the upper portion of the attic. In other words some exhaust vents may pull air in through another exhaust vent and exhausting out through another exhaust vent close by ... creating a short circuit.

Another example could be if there are exhaust vents located higher on the roof along with existing gable end vents .... the gable end vents could end up being intake vents with the air exchange only occurring at the upper portion of the attic.

In your case with a powered type of fan that moves a large volume of air .... if there is a restriction of lower intake air then these powered type of fans will draw air in from wherever they can. So if you have 2 of these types of vents and one is working more than the other ...... then the stronger one could in theory be drawing air in form the other weaker vent creating a short circuit as well.

All this can occur if there aren't any soffit vents or if they exist may be blocked.

Now having said all this ....

The attic vents don't really have any direct effect on drawing the heat out of the living space but rather trying to regulate the temperature within the attic.

The insulation in the attic is there to provide the resistance for heat loss from the lower living space in the winter and radiant heat gain from the warmer attic in the summer.

With regard to your situation it's difficult to pin point the cause for home to be very warm.
There may be lack of insulation in the walls also in the attic that may need to be increased.
Solar gain from south and west facing windows will have a large impact as well.

Hopefully this makes sense and helps. :)

Re: Help with Attic Fans

Well to jump into the fray, turbine vents do work when they are not turning. You still have a 12" or 14" hole in the roof so it works like any other passive roof vent. When the wind blows they turn and are more efficient at removing the hot air just like an electric fan type.

If you are not getting proper ventilation of the attic it is most likely that added insulation or something else has covered the cool air intakes. Without the intakes you do not get proper air flow and the first turbine to turn draws air in through the other turbine. That would be called a short circuit and the drawn in air would be hot coming off the roof surface.

I think your best course of action would be to find and free up the intakes. The
cooler the attic the cooler the house because the heat from the house will rise toward the attic unless it is not properly vented.

Re: Help with Attic Fans

The only thing I would add is get a new step ladder so you can get up in the attic and inspect things. Every new house usually needs a new set of ladders, be they step or extension.

Gray Watson
Re: Help with Attic Fans

Have you found a solution to your problem yet?


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