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# Ceiling fan and roof pitch--54 in. OK with 6 in. drop rod?

#1
02-28-11, 06:40 PM
Member
Join Date: Feb 2011
Location: USA
Posts: 6
Ceiling fan and roof pitch--54 in. OK with 6 in. drop rod?

I have a new home that I am purchasing ceiling fans for. The ceiling has a 3.5 pitch. With a 6 in. drop rod, am I OK with fans with 52-54 in. blade span? Or do I need to stick with 44-48 in. (which are hard to find these days)?

Secondly, if possible, can someone provide the math? I've read that a 3.5 pitch is a 14 degree angle, but I don't know if the source is reliable or not.

#2
02-28-11, 07:13 PM
Member
Join Date: Apr 2009
Location: Maryland
Posts: 334
How high is the ceiling? If the ceiling is 9 or 10 feet I would like a longer drop due to better air circulation. The fan gets more ineffective the closer it gets to the ceiling.

Roof Pitch Table
1 12 4.76°
2 12 9.46°
3 12 14.04°
4 12 18.43°
5 12 22.62°
6 12 26.57°
7 12 30.26°
8 12 33.69°
9 12 36.87°
10 12 39.81°
11 12 42.51°
12 12 45°

#3
03-01-11, 05:44 AM
Member
Join Date: Feb 2006
Location: USA
Posts: 6,906
Math

12/3.5=3.43
6" x 3.43 = 20.58"
Add to the 6" down rod the height of the hood and do the calculation on the line above to get the allowable horizontal distance from the center line of the fan to the end of the blades.

#4
03-01-11, 06:46 AM
Member
Join Date: Feb 2011
Location: USA
Posts: 6
Nine feet to the ceiling for the lower of the two (10 feet for the other). A 6 in. drop leaves the fan bottom 7 feet 7 in. above the floor. To drop another six feet will bring it to just about seven feet.

Originally Posted by bish80
How high is the ceiling? If the ceiling is 9 or 10 feet I would like a longer drop due to better air circulation. The fan gets more ineffective the closer it gets to the ceiling.

Roof Pitch Table
1 12 4.76°
2 12 9.46°
3 12 14.04°
4 12 18.43°
5 12 22.62°
6 12 26.57°
7 12 30.26°
8 12 33.69°
9 12 36.87°
10 12 39.81°
11 12 42.51°
12 12 45°

#5
03-01-11, 08:11 PM
Member
Join Date: Apr 2009
Location: Maryland
Posts: 334
Does the ceiling come to a point or is it flat on the top like a trapezoid and if so, what is the measurement of the top side. If it is a trapezoid, you will need that info to use Wirepuller38's calculation.

#6
03-01-11, 09:09 PM
Member
Join Date: Feb 2011
Location: USA
Posts: 6
Shed roof

It's a large shed roof. No point, no apex.

Originally Posted by bish80
Does the ceiling come to a point or is it flat on the top like a trapezoid and if so, what is the measurement of the top side. If it is a trapezoid, you will need that info to use Wirepuller38's calculation.