My attic fan started squeaking this morning. It was running at a very low rpm. It would start up and then stop less than a minute later.
I went into the attic (almost passed out) and tried to see if there were any lube points. I couldn’t see any. Went to HD and Lowes, picked up a new thermostat and fan motor. Was gone for about an hour.
Came back and the fan is running just fine at what appears to be full speed and no squeaks. Go figure.
Any ideas why it behaved that way? I’ll monitor it for the next few days but it seems to be working.
Could it be the thermostat going? Do attic fans have built in protection to prevent them from running too hot?
Replies
Sounds like the bearings have dried out, but could be a starter cap or some such (if the unit has one).
Is this a "whole house fan" or a gable or rooftop vent fan? Does it have a belt?
The normal life of a gable/rooftop fan motor is about 3 years -- the bearings get dry. You can usually extend the life another 2 years or so if you take the motor out and dribble oil into the bearings, thouigh this is generally a difficult task.
It's a rooftop vent fan. It's at least 10 years old. I moved into the house in 2000 and it's been running fine until now.
Can you explain what a starter cap is?
3 years seems like a pretty short amount of time given the amount of effort it would take to replace a fan (nevermind the entire vent). I bought a replacement motor that is the same diameter as the old motor. It looks like the motor is held in place by 4 metal supports that form a "circle clamp" around the motor house.
I'll continue to monitor the fan; if it needs replacement, I'm crossing my fingers and hoping that the motor can be replaced from the inside (instead of climbing on the roof.)
Starter cap (capacitor) is the oblong lump you see on the side of some motors. Generally only seen on larger motors -- some "whole house" motors, but would be rare on a rooftop vent.
I've been successful in removing/replacing the fan motor from the inside -- the hard part is disconnecting the wires. Might actually be easier from above, though, if quarters are cramped in the attic. The critical features of the motor are it's overall diameter (for the clamp) and the size/shape of the shaft. If those are matched then the replacement should work. (There's also rotation, of course, but I'm guessing that they're mostly the same in that regard.)
The frequency of service/replacement is one of the several reasons that rooftop vents are not that good of a deal. You're lucky in a way in that you heard it squeal, vs just having it seize up silently.
Does the motor/fan spin freely...
or at least smoothly, when there is no power to the motor? Make sure there is no power before sticking your hand in there... :-) If it was squeeling and there is no belt it is the motor bearing(s).
re >> I bought a replacement motor that is the same diameter as the old motor. << Having it phisically fit is the first step but it needs to be the same/similar RPM too.
I did not check that since I didn't turn the power off. It has been running relatively noise free. My concern is whether it is running at full capacity or not. It seems to be running at full rpm but since I have no way of measuring that, I can't say for sure.
I will check the free spin (as it's not hot enough in the attic this morning yet to kick in).
Murphy's Law strikes again
Well, after more than a week of quiet operation, the fan bearing finally bit the dust. Of course it bit the dust on July 4th. Just as we were packing up and getting ready to drive away, the bearing start screaming like a banshee. You could hear it out in the street.
I checked it to make sure the overload circuit protector was working so there was no fire hazard before leaving (what else could I do with a bbq to go to and HD/Lowes closed.)
Replaced the fan today...what a pain. I picked up a complete roof van vent unit from HD. Got lucky...the fan and mounting brackets were the same size as the dead unit so I proceeded to contort my body in 100f+ heat and got it replaced from the inside. I did have to go onto the roof to tighten the nuts on the bolts from the outside...caulked them too while I was at it to make sure it they were leakproof and wouldn't work their way loose.
So far so good and I have a new fan and thermostat.
H*LL ON EARTH is 4 hours in a 110f+ attic!!!!
You should have eave vents to allow the air in (and gable vents should be blocked off if not being used for a fan). The problem with gable vents (for air intake) is that there's no ventilation of the lower 2/3rds of the roof -- just the top.
In terms of gable fan vs rooftop, the main difference is that a single rooftop fan can be more centrally located & hence provide more even ventilation.