Welcome to City-Data.com Forum!
U.S. CitiesCity-Data Forum Index
Go Back   City-Data Forum > U.S. Forums > Texas > Houston
 [Register]
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
View detailed profile (Advanced) or search
site with Google Custom Search

Search Forums  (Advanced)
Reply Start New Thread
 
Old 08-21-2017, 08:29 AM
 
Location: Houston
455 posts, read 517,248 times
Reputation: 412

Advertisements

I had some roofing work done when i purchased my house a few years ago. It had a non-functioning attic fan. The roofer said, sure, he could replace it but in his opinion, the issue is that when they break, no one is usually aware that it has stopped working. In his opinion, the standard "manual" whirlybird style turbine was the way to go since it rarely breaks and does as good of a job. Anyway, i went with the latter option but knowing the pros and cons, they are both effective.
Reply With Quote Quick reply to this message

 
Old 08-21-2017, 09:15 AM
 
18,041 posts, read 25,061,271 times
Reputation: 16721
Quote:
Originally Posted by WRM20 View Post
The motors lock up, then start a fire. There's no need to use a fan to move air out of the attic.
http://ep-us.mersen.com/fileadmin/ca...Protection.pdf

Overload Protection
The NEC or CEC allows fuses to be used as the sole
means of overload protection for motor branch circuits. This
approach is often practical with small single phase motors.
If the fuse is the sole means of protection, the fuse ampere
rating must not exceed the values shown in Table 1.



They recommend using fuses rated 125% of the motor full load ampere (nameplate amperage)
if your fan motor is rated 10amps, your fuse should be 12.5amps (time delay fuse)
Reply With Quote Quick reply to this message
 
Old 08-21-2017, 08:28 PM
 
15,088 posts, read 7,138,928 times
Reputation: 18956
Quote:
Originally Posted by sonic0boom View Post
I had some roofing work done when i purchased my house a few years ago. It had a non-functioning attic fan. The roofer said, sure, he could replace it but in his opinion, the issue is that when they break, no one is usually aware that it has stopped working. In his opinion, the standard "manual" whirlybird style turbine was the way to go since it rarely breaks and does as good of a job. Anyway, i went with the latter option but knowing the pros and cons, they are both effective.
We removed the whirlybirds. They don't really move much air, and tend to fail in high winds, usually when it's raining hard, creating a 12 inch hole in your roof. Passive vents work fine, assuming you have soffit vents
Reply With Quote Quick reply to this message
 
Old 08-21-2017, 08:29 PM
 
15,088 posts, read 7,138,928 times
Reputation: 18956
Quote:
Originally Posted by Dopo View Post
That's easily fixed by using fuses.
Not necessarily. If a fan locks up, the current draw may not spike, but the motor gets hot, then catches fire, because there's no airflow around it.
Reply With Quote Quick reply to this message
 
Old 08-21-2017, 09:18 PM
 
18,041 posts, read 25,061,271 times
Reputation: 16721
Quote:
Originally Posted by WRM20 View Post
Not necessarily. If a fan locks up, the current draw may not spike, but the motor gets hot, then catches fire, because there's no airflow around it.
How is the current not going to go up when the torque is going up?
It's like saying that you drive a car uphill and the RPM didn't go up
Reply With Quote Quick reply to this message
 
Old 08-22-2017, 07:34 AM
 
15,088 posts, read 7,138,928 times
Reputation: 18956
Quote:
Originally Posted by Dopo View Post
How is the current not going to go up when the torque is going up?
It's like saying that you drive a car uphill and the RPM didn't go up
When I drive uphill in my standard transmission vehicle, RPM do not go up. RPM may go up in an automatic transmission vehicle due to the torque converter. In either case, you may have to increase engine power to maintain speed, but in a locked system, the RPM for a given speed doesn't change.

For an electric motor, the current draw for a stalled motor depends on a number of factors, and if the maximum current draw when stalled is less than the current required for startup, you won't be able to fuse it correctly.

Feel free to install a potential fire hazard in your house, but I won't be putting one in mine, since passive methods work just fine.
Reply With Quote Quick reply to this message
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.

Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.


Reply
Please update this thread with any new information or opinions. This open thread is still read by thousands of people, so we encourage all additional points of view.

Quick Reply
Message:


Settings
X
Data:
Loading data...
Based on 2000-2020 data
Loading data...

123
Hide US histogram


Over $104,000 in prizes was already given out to active posters on our forum and additional giveaways are planned!

Go Back   City-Data Forum > U.S. Forums > Texas > Houston

All times are GMT -6.

© 2005-2024, Advameg, Inc. · Please obey Forum Rules · Terms of Use and Privacy Policy · Bug Bounty

City-Data.com - Contact Us - Archive 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37 - Top