Hi Everyone,
I am an home owner leaving in Hawaii and have a question regarding a whole house fan system I would like to build.
Here is the situation. We have a very large living room with a cathedral ceiling. This room shares a wall with the attic, with three windows located on the opposite side. We have little to no cross ventilation and the living room get really hot in the summer. In order to address the situation, we have installed a solar attic fan (36W, 1,600 CFM). It did cool the attic but had no impact (or very little) on the living room temperature. In a desperate attempt, I have added a vent into the wall adjacent to the attic, hoping the attic fan would help pulling some air out from of the living room, but this also did not help the situation (see attached picture for details). I am now leaning towards a whole house fan setup. I have looked around for complete system but I am quite surprised by the cost, such as the one from QuiteCool ($800+), where the cost of the same fan sold separately is less than $250.
So, my idea is to use one gable fan to suck up air via ducts attached to three vents dispatched into the room (so adding two more on the attic wall toward the back of the room in this picture). The total room volume is 8,000 cubic feet. So I think Quiet Cool's AFG-PRO-3.0 (3000 CFM, $199) should in theory do the job. I am planning on building a "junction box" to connect the three ducts to the gable fan intake, like a 1.5"x1.5"x1.5" wood box, with a 15" hole for the fan and smaller holes on three sides of this box for the ducts.
One my my main concern is picking the right duct diameter. I assume each duct will be about 15-20' long. The Fan would suck up air from all three ducts at the same time, all running in parallel, so each line would be about 1,000 CFM. Quiet Coll complete systems comes with a single 15" diameter duct. I am not sure if this is to simplify the design (no need for reducers) or if this size is mandatory.
Right know I am leaning toward 8" diameter ducts, maybe 6". Do you think this could restrict the CFM significantly? Would you have any advise to share or even better solution to this problem?
Aloha, Mokuleia
I am an home owner leaving in Hawaii and have a question regarding a whole house fan system I would like to build.
Here is the situation. We have a very large living room with a cathedral ceiling. This room shares a wall with the attic, with three windows located on the opposite side. We have little to no cross ventilation and the living room get really hot in the summer. In order to address the situation, we have installed a solar attic fan (36W, 1,600 CFM). It did cool the attic but had no impact (or very little) on the living room temperature. In a desperate attempt, I have added a vent into the wall adjacent to the attic, hoping the attic fan would help pulling some air out from of the living room, but this also did not help the situation (see attached picture for details). I am now leaning towards a whole house fan setup. I have looked around for complete system but I am quite surprised by the cost, such as the one from QuiteCool ($800+), where the cost of the same fan sold separately is less than $250.
So, my idea is to use one gable fan to suck up air via ducts attached to three vents dispatched into the room (so adding two more on the attic wall toward the back of the room in this picture). The total room volume is 8,000 cubic feet. So I think Quiet Cool's AFG-PRO-3.0 (3000 CFM, $199) should in theory do the job. I am planning on building a "junction box" to connect the three ducts to the gable fan intake, like a 1.5"x1.5"x1.5" wood box, with a 15" hole for the fan and smaller holes on three sides of this box for the ducts.
One my my main concern is picking the right duct diameter. I assume each duct will be about 15-20' long. The Fan would suck up air from all three ducts at the same time, all running in parallel, so each line would be about 1,000 CFM. Quiet Coll complete systems comes with a single 15" diameter duct. I am not sure if this is to simplify the design (no need for reducers) or if this size is mandatory.
Right know I am leaning toward 8" diameter ducts, maybe 6". Do you think this could restrict the CFM significantly? Would you have any advise to share or even better solution to this problem?
Aloha, Mokuleia
