Bathroom fan not pulling air


Old 09-22-13, 10:50 AM
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Bathroom fan not pulling air

Let me start by apologizing for how long this post is. I have a house that has a bathroom that is 5x11 and 8 tall. The fan did not appear to be working as anytime you take a shower, the entire room fogs up and there is condensation on all the walls. It had a very small Nutone fan in it and I decided to replace it. I replaced it with a NuTone QTN130E (130 CFM). It is complete overkill for this size room per the sizing specs I have seen online. In the attic, the vent is with the 4 flexible tubing. It comes out of the fan and makes a gentle left turn and then goes 22 to the exterior wall. However, the new fan has not changed anything.

Here is what I have tried to troubleshoot:
1. I first tried the plastic bag test the bag did not hold onto the grate

2. Next, I left the door open (in case of a vacuum issue), but that did not help.

3. Next, I got on the ladder outside (as the vent is near the roof) and had my wife switch on the fan. There was a lot of air coming out of the vent. I was very confused by this. I expected little to no air coming out. The air seemed hot and humid too since we had the hot shower running.

4. Lastly, I removed the vent from the bathroom fan so that it would vent directly into the attic. Obviously, I could not leave it that way, but I wanted to test. There was a lot of air coming out of the vent hole from the fan. Even with no vent pipe and the bathroom door open, the bathroom still got too hot and began to fog the mirrors and water condensate on the walls.
Obviously, the fan is moving air, but it does not feel like it is moving it from the bathroom even without vent pipe. Also, with the grille removed from the bathroom, I put my hand up near the fan, but felt little air being pulled up into the fan.

Any ideas would be greatly appreciated.

Thank you
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Old 09-22-13, 11:21 AM
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My only thought would be to make sure that the fan housing is even with the interior edge of the bathroom ceiling. If it is mounted higher, it could be pulling air from the attic rather than the bath.
Old 09-23-13, 02:36 PM
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OK - I tried sealing the edge of the fan against the sealing with caulking and also putting some duct tape over any little holes in the housing. Still no difference :-(

Thanks for the suggestion.

Any other ideas?
Old 09-23-13, 06:11 PM
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Those fans aren't designed to move a lot of air. I've never seen one keep the bathroom "steam free."

Based on the room size you're right.... the fan you selected should be sufficient..... but the 22' of 4" flex duct is working against you.

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