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Old 08-26-2009, 04:20 PM   #16
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New Attic Fan Didn't last a day


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@J.V., well my brother wasn't able to help, but he did allow me to use his tools. Everything was working fine last night; however, I plan to check to make sure everything is still working when I get home from work.

@Wildie, when you say supply ventilation, you mean other vents in the attic to allow air to flow in right? If that's the case then I believe I have 3 other shutters/vents.
Yes! You must have vents such as soffit vents etc!

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Old 08-27-2009, 11:53 AM   #17
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New Attic Fan Didn't last a day


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Yes! You must have vents such as soffit vents etc!
What do you mean by that? Restricting air flow lowers current. Blocking the suction or discharge side of any fan will cause the current to plummet.
Is there something about attics that would make this fact untrue?......Thanks
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Old 08-27-2009, 07:15 PM   #18
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New Attic Fan Didn't last a day


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What do you mean by that? Restricting air flow lowers current. Blocking the suction or discharge side of any fan will cause the current to plummet.
Is there something about attics that would make this fact untrue?......Thanks
I'm not a physicist, but if you have a sealed room with a fan drawing air out it will lessen the atmospheric pressure in the room.
Outside atmospheric pressure wants to flow back into the room and equalize the pressure!
If the fan is running in a certain direction, and then power is abruptly stopped, the fan will stop and then start to rotate in the opposite direction, as air flows back into the sealed room as the pressures equalize.
This demonstrates the forces acting on the fan load.
Even though the fan may be running and blowing outwards, the outside atmospere is attempting to equalize the inside pressure, countering the outflow.
The result being a greater load on the fan motor.
If the room has an incoming air vent then the fan load is relieved as the incoming equalization will enter here rather than working against the fan.
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Old 08-28-2009, 07:45 AM   #19
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New Attic Fan Didn't last a day


Hey guys, I have a guy coming out tomorrow morning. He's replaced motors, fan blades and entire units. Lets hope all goes well.
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Old 08-28-2009, 11:41 AM   #20
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New Attic Fan Didn't last a day


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I'm not a physicist, but if you have a sealed room with a fan drawing air out it will lessen the atmospheric pressure in the room.
Outside atmospheric pressure wants to flow back into the room and equalize the pressure!
If the fan is running in a certain direction, and then power is abruptly stopped, the fan will stop and then start to rotate in the opposite direction, as air flows back into the sealed room as the pressures equalize.
This demonstrates the forces acting on the fan load.
Even though the fan may be running and blowing outwards, the outside atmospere is attempting to equalize the inside pressure, countering the outflow.
The result being a greater load on the fan motor.
If the room has an incoming air vent then the fan load is relieved as the incoming equalization will enter here rather than working against the fan.
No air to move, means less work and that means less current. This is a fact, not a theory. Same with a pump. Restrict the flow, you lower the current. Thats just how it is.

Now your comments regarding back flow? I see your point. It is highly possible if the fan is turning in the wrong direction and then it cycles on, that would cause an increased current for as long as it took to get the fan running in the right direction and the right RPM. You would think the manufacturer would have provisions to prevent this? Good question!

Maybe someone will chime in that knows more about this? Maybe an HVAC tech?
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Old 08-28-2009, 12:01 PM   #21
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No air to move, means less work and that means less current. This is a fact, not a theory. Same with a pump. Restrict the flow, you lower the current. Thats just how it is.

Now your comments regarding back flow? I see your point. It is highly possible if the fan is turning in the wrong direction and then it cycles on, that would cause an increased current for as long as it took to get the fan running in the right direction and the right RPM. You would think the manufacturer would have provisions to prevent this? Good question!

Maybe someone will chime in that knows more about this? Maybe an HVAC tech?
I can see your point if the fan is in perfect vacuum, but its not. There are complex elements at work for an attic fan.
Anyway, back to the original problem! He wants to move hot air from his attic and I suggested that he should have incoming venting.
Much the same way in which a forced air heating system works, with its cold air return. Same idea!
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Old 05-29-2012, 05:38 PM   #22
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New Attic Fan Didn't last a day


What was the resolution to your problem?
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Old 05-29-2012, 06:07 PM   #23
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New Attic Fan Didn't last a day


Not sure the OP is still going to be here following this thread after almost 3 years.
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Old 05-29-2012, 06:49 PM   #24
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Not sure the OP is still going to be here following this thread after almost 3 years.


Pgeeman,

seriously, im sure you didnt sign up just to follow-up on this old issue, but i wonder if you are having similar trouble and need help. if so, please post details, pics or both
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Old 05-29-2012, 08:31 PM   #25
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I was reseaching a problem I am currently having when I came across your similar problem. I replaced 2 motors in the past 2 days and have no idea what to do. I checked voltage, thermostat and they are OK but never replaced the fan blade. The fan worked when I replaced the motor but when I went back to check on it later - it wasn't workinging. I was curious how you solved the problem.
Would be very much interested in an answer before I get an expert to look into it.
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Old 05-29-2012, 09:11 PM   #26
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New Attic Fan Didn't last a day


I have had my share of fun with wiring attic fans.

1, is there a disconnect switch somewhere? or a switch in the hallway you arent sure what it does. someone might have flipped it
2. are you sure a breaker hasnt tripped
3. there is usually a little toggle switch on the fan box to turn on the fan even if its below the thermostat temperature
4. most newer fans shut off if the temp exceeds 135 degrees in the attic to prevent the fan from possible increasing oxygen flow to an attic fire
5. you might have a loose connection between the box and the actual fan (there is usually a 2 foot section of armored cable between the 2 to protect the conductors. that is 4 places a connection with the hot and neutral can be loose
6. you could have a mechanical issue that is causing the motor to work too hard and burn out
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Old 05-30-2012, 07:34 AM   #27
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@pgeeman, in the end, I ended up having someone replace the entire attic fan. My brother recommended a guy he use to work with. Last year my house got hit pretty hard by hurricane Irene and I ended up having my roof replaced. I currently don’t have an attic fan because the roofer convinced me I didn’t need it. Supposedly it’s not needed because the new roof is vented. I figure, if need be, I could just install a gable fan. I have three gable vents on my house. I recommend you have a professional or a handyman replace the entire fan.
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Old 05-30-2012, 07:36 AM   #28
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Not sure the OP is still going to be here following this thread after almost 3 years.
wow, i guess we have our answer!
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Old 05-30-2012, 08:26 AM   #29
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Thanks for your quick answer. I appreciate your help and decided last night to have the entire unit replaced (you backed up my decision) - I'll go to Home Depot and have them install it and then have a warranty against any problems if they should occur again.
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Old 05-30-2012, 08:36 AM   #30
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Thanks for your quick answer. I appreciate your help and decided last night to have the entire unit replaced (you backed up my decision) - I'll go to Home Depot and have them install it and then have a warranty against any problems if they should occur again.
I haven't seen anything installed by Home Depot that has lasted or that was installed correctly. Call a roofing contractor.

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