WH Fan not pulling as much air

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Old 08-16-12, 11:37 AM
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WH Fan not pulling as much air

When I first installed this fan, I did have to use doorstops in some rooms to kepp doors open. Now it just isn't pulling the same air. Not even close. I can't tell by looking or even by sound. No noise other than the sound of aircraft landing. Has always been that way, but ok with everyone because it really cooled the house down. It's not belt driven, its about 5 years old and has had one motor replaced already. Before I replace it, what few things can I check? I blew it out with the compressor in case of dust or something like that. Visual inspection checks out. Thanks in advance
 
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Old 08-16-12, 01:26 PM
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Have you checked the belt tension or is this a direct drive motor?
 
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Old 08-16-12, 01:58 PM
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Ray - OP did say not belt driven.

My thought at this point is the exhaust - anything blocking the airflow after the fan?
 
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Old 08-16-12, 02:05 PM
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Exiting air is one thing to check out. Entering air is another. Do you leave windows cracked the same way as you did before? No air in will mean no air out.
 
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Old 08-16-12, 03:10 PM
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Sorry, direct drive. Windows are the exact same. I have a routine. When the fan was installed the guy put an exhaust fan in the attic. It comes on on a thermostat. It is working. Plus our house style has those holes from the attic to the outside. So nothing should have changed. Maybe the air circulation up there has blown some insulation over those holes???? I'm not sure I understand. But I do appreciate the help.
 
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Old 08-18-12, 05:42 AM
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Have you any equipment that is ducted to the outside added recently IE kitchen grille, fireplace, gas appliances, etc? Outside air will take the path of least resistance coming in; if a fireplace damper is left open, for instance, this is a large duct that easily acts as a conduit for incoming air. Also, are you opening the windows closest to the fan much less than those further away? I use a WH system also and must be careful to keep the closest windows only open a little. If all checks out, do an amp draw check on the WH fan motor, if it is drawing higher than rated amps, you may have a shorted motor not turning the correct rpm.
 
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Old 08-18-12, 07:28 AM
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do an amp draw check on the WH fan motor, if it is drawing higher than rated amps, you may have a shorted motor not turning the correct rpm.
To measure the amperage the fan is drawing, use a clamp-on ammeter clipped around the cord or cable supplying the fan. A higher reading than the value specified on the fan's nameplate (look for FLA, for Full Load Amps) may also indicate that the fan is fighting a heavier load than it was designed for, and needs a good cleaning.
 
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Old 08-18-12, 08:37 AM
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Just to clarify Nash meant one wire of the cable (other then ground). Not the outer sheath of the cable.
 
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Old 08-18-12, 09:20 AM
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Just to clarify Nash meant one wire of the cable (other then ground). Not the outer sheath of the cable.
Yes, I did. Thanks for making that clear, Ray.
 
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Old 08-18-12, 01:42 PM
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What are "those holes from the attic to the outside"?? Hopefully you are talking about a gable vent. That little motorized vent fan was money down the tubes. Let us know what type exit venting you have in the attic. You should have soffit venting as well.
 
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Old 08-18-12, 02:07 PM
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Well, he says thermostat controlled exhaust fan in attic. My guess is either a roof fan or gable fan.

Holes that could get blocked by insulation? Usually soffit vents.

Still don't know if he opened some windows to get air flow.

Only other thought is that it might be a multi speed motor and is set on the wrong speed.

Years back I had a belt drive with a two speed motor and wall switch.
 
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Old 08-18-12, 02:35 PM
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Well, he says thermostat controlled exhaust fan in attic.
More money down the tubes for the thermostat, and for the power that thing draws.
 
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Old 08-24-12, 11:40 AM
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If you have blown-in insulation, the WHF and/or wind may have blown it down onto your soffit vents, clogging them. Might want to check that. Baffles should be installed to keep that from happening.
 
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Old 08-24-12, 12:40 PM
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WHFs are usually used with gable vents. It may well be insulation has partially clogged the soffit vents. Long term solution may be to add gable vents if you don't already have them
 
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Old 09-13-12, 12:53 PM
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Hey guys, I'm back. Sorry. Computer down too. When it rains it pours. To answer some questions: Yes, they are soffit vents. Didn't know terminology. Have gable fan on thermostat. Waste of money or not. WHF worked fine before. It is a two speed fan. With a pull chain on the actual fan. But it is also on a wall thermostat. I never change the fan speed. I just go to wall swith and turn it to 65 degrees and it comes on. I will check to make sure no one else has changed fan speed at chain, but I'm 90% I already did that when I noticed the vents not opening as far. But clearly the fan blades are not spinning as fast. Someone mentioned claening the motor, not sure what I'd do other than blow it out? Will also check amp load
 
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Old 09-13-12, 02:07 PM
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If the speed control is a rheostat, it could be a problem. Have you tried replacing the thermostatically controlled switch with a standard "on-off" switch?
 
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Old 09-13-12, 02:27 PM
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The wall on/off unit is a "dial" that has "80" over in the far left or off position and "60" I think on the right. House is 80 degrees and you turn the dial to right and it comes on until temp drops. I think that is a rheostat or whatever. I have not tried that. But the dial does NOT determine the fan speed is that is what you are asking.
 
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Old 09-13-12, 02:31 PM
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No, it's not a rheostat, its more like a therostat. The ONLY fan speed adjustment is the chain pull hanging from the fan...two speed.
 
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Old 09-13-12, 03:06 PM
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Does the fan still change speed when you pull the speed control switch? Some motors use a capacitor as part of the speed control. It could be a bad capacitor if that is the case or just a bad switch.
 
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Old 09-13-12, 03:40 PM
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Yes, it goes slower. for sure changes speeds.
 
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Old 09-14-12, 12:41 PM
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Probably a repeat question but I can't remember. Have you checked that all the soffit vents are clean?
 
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