Here's some photos of 3 attic fans. The dates on the photos are wrong
and not in order due to camera snafus.
Vent from inside attic, before fan installed
I mounted it on 1/4-in plywood first because there was nowhere to
conveniently mount it to the studs without blowing air back into the
Fan installed ready for wiring
Fan as installed
Thermostat as installed. Ended up moving it to a hotter location and
setting it at 110 deg F. Was not reliable leaving it mounting in the
fan intake. I don't use leave the fan powered -- just use the
thermostat to tell me when it's hot enough to run. Also it will shut
the fan off in case I forget. But I don't depend on it.
Different vent fan - was too noisy and vibrated off center-- returned
Roof-top fan on a different house - it looked like a space ship on the
roof so I painted it with Rustoleum. If you install on of these, be
sure you seal it good and slide it up under the shingles properly. I
wouldn't install one of these again because of the windy rains we get.
Also I don't like cutting holes in the roof.
On Tuesday, June 17, 2014 10:28:13 PM UTC-4, Guv Bob wrote:
ake. I don't use leave the fan powered -- just use the thermostat to tell
me when it's hot enough to run. Also it will shut the fan off in case I fo
rget. But I don't depend on it.
seal it good and slide it up under the shingles properly. I wouldn't inst
all one of these again because of the windy rains we get. Also I don't lik
e cutting holes in the roof.
A key concept with soffit vents combined with a rigdge vent is that
you have equal air intake down low and exhaust up high. If you choose
to use a fan, you have to consider what size fan, how much air it moves
and where that air is going to come from. If he just puts in a gable
fan, with the existing ridge vent, it's not likely to do much good.
Most of that forced air is likely to short circuit, via the ridge vent.
IDK how Derby will feel about that, but it's how I see it when you
introduce a fan. Just a natural gable vent and a ridge, I can see how
it's debatable, but when you have a fan, I think it's very likely to
be of little benefit, unless you close off the ridge vent in the area
of the fan. And I think adding a powered roof vent is not of much
benefit, for the same reason.
And with a powered fan, if you don't have adequate/matching air intake,
you can wind up sucking conditioned cool air from the living space via
any recessed lighting, through bath fan openings, outlets, etc. because
you've created a negative pressure in the attic.
Is exactly what you see when you look under this "space ship":
I have two of those on my roof. For one of them, I raised the "space
ship" top-hat by about 8 inches using 2x2 pieces of wood. I also
installed a taller screen to match the new height. The extra height
improves airflow. The wood struts are unequal length so the top-hat
sits level (with the ground - not with the roof). This keeps rain out
(yea, we get windy rain too sometimes).
You want a ventilated roof, you're gonna have to cut holes in the roof.
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