Looking for ideas...

[inspectored]

I have run into this problem with these motors they come eqipped with a thermal protector inside the motor housing, what I have seen is a short piece of lead across a set of contacts when the motor overheats this one time protection device opens, I guess this would be called a poor mans overload protector.

 

[1793]

I just don't know...

I just don't know...

Well the newest motor has stopped working. I'm beginning to think I have the blades too high on the shaft so there is nowhere for the air to go. Could this cause the motor to work too hard and burn out?

 

[RayS]

Well the newest motor has stopped working. I'm beginning to think I have the blades too high on the shaft so there is nowhere for the air to go. Could this cause the motor to work too hard and burn out?

could also be that there is no where for the air to come from...
must...have... air

 

[1793]

could also be that there is no where for the air to come from...
must...have... air

My problem seems to be the motors stop working only after a week or so. All I had done originally was replace just the motor for the fan. The housing has stayed unchanged.

There have not been any other changes to the attic. The original fan worked for about 8 years.

I'm at a loss.

 

[RayS]

oh. just reread the op.
still have the original motor? is the new an exact replacement, not just in speed and HP, but bearings, temp rating, position etc?
Some fan motors (box fans for windows) die quickly when run with the blades not vertical

 

[dnem]

Everyone is talking ambient temp and pressure issues or motors that are made like crap, which are the most probable reasons.

But if none of those check out, the next thing I would look for is bad connection on a 3wire HR neutral. . You always get 240v line to line but if your noodle connection is hit and miss, the line to neutral can be 120v sometimes and half voltage or one and a half voltage at other times, all depending on the loads connected to each line. . You can have a series 240v circuit that might not bother the ceiling fans but burns out the attic vent fan because it's simply more voltage sensitive.

David

 

[acrwc10]

Everyone is talking ambient temp and pressure issues or motors that are made like crap, which are the most probable reasons.

But if none of those check out, the next thing I would look for is bad connection on a 3wire HR neutral. . You always get 240v line to line but if your noodle connection is hit and miss, the line to neutral can be 120v sometimes and half voltage or one and a half voltage at other times, all depending on the loads connected to each line. . You can have a series 240v circuit that might not bother the ceiling fans but burns out the attic vent fan because it's simply more voltage sensitive.

David

I was thinking along this line also, I would check the splices and connections upstream of the fan. If you have to long of a wire run or a weak connection it could cause a voltage drop that you would not see with no load on the circuit. But once load is on this may cause a "brown out" that could cause under voltage at the fan motor. It is simmilar to when you see some one run long extention cords to skill saws on the job, the saw motors work but don't last very long. If the fan is on the same circuit as some other load in the house that maybe on when your not there this could also brown out the circuit. Voltage drop is a killer especially to cheap motors.

 

[1793]

I was thinking along this line also, I would check the splices and connections upstream of the fan. If you have to long of a wire run or a weak connection it could cause a voltage drop that you would not see with no load on the circuit. But once load is on this may cause a "brown out" that could cause under voltage at the fan motor. It is simmilar to when you see some one run long extention cords to skill saws on the job, the saw motors work but don't last very long. If the fan is on the same circuit as some other load in the house that maybe on when your not there this could also brown out the circuit. Voltage drop is a killer especially to cheap motors.

I'll see if I can install yet another motor and check for VD. I think I'm going to look into lowering the fan blades as well. I'm really getting tired of this attic.

 

[cschmid]

question are the fan blades shaft mounted or pulley driven? when the motors running amp the motor. If amps are at 100 % of rating than close attic access and see amps go up. Then you can tell if you have a supply air problem if they stay the same with heat and max amps on motor life is cut real short, couple of brown outs due to poor connection some where, life of motor shortened even more. Now add blade imbalance due to many handling's and probable cheap materials to aid in cheaper upfront costs and you have a very expensive problem. Now if fan blade is pulley driven change the drive pulley and down size it 1/2" and it will change the amps under full load and also change blade speed which will change amount of air removal but should make motor run longer. Next move I would change whole unit it is cheaper for you and home owner in long run.

 

[Oakey]

Norb I'm real curious how this turned out if you dont mind. :smile:

 

[1793]

Norb I'm real curious how this turned out if you dont mind. :smile:

Funny you should ask this today.

HO and I talked and I will be replacing the entire Power Vent with a new one in about a week or so.

There are too many variables, blades bent, blades too high, some type of voltage issue while I'm not there.

New fan will take out a few of these, I hope.

 

[acrwc10]

Howbout a solar powered fan:roll:

 

[1793]

I'm ready to...

I'm ready to...

Just installed an entirely new Power Vent yesterday.

Last night I get a call from the HO who said he could not hear the fan running. We had a very hot day yesterday and it should have come on. It is conceivable that the new fan is so quiet that he could not hear it running.

Unless I get a call today, I'm planning on going by late today, after the attic has had time to "Heat Up".

By the way, I did have the fan operating, testing at a lower temp., when I left.

 

[1793]

At last...I hope

At last...I hope

HO called today and indeed the fan is working. The new fan has very little vibration and he was unable to hear, through the framing of the hose, the fan running.

Now lets see for how long this lasts.

Thanks to all for your input and support.