Tricky Bath Exhaust Fan


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Old 12-11-21, 05:55 PM
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Tricky Bath Exhaust Fan

Hello all! This time around I am upgrading the existing 50 cfm fan in my master bath to a 110 cfm unit with an LED light. There are some challenges with this one. First of all, from topside in the attic, all I can see of the current install is the power wire that goes up near the roof then down to the fan, buried somewhere in the pink insulation. Vaulted ceiling. This will definitely be a "roomside" install and that is what the Broan fan I bought advertises.

The challenge I need help with here is routing a new 4" exhaust duct to replace the current suspected 3" hose. The bath I did last year had a 3" hose on it so I assume this does as well. The current hose runs down along the top of the ceiling and an exit is fabricated into the overhanging soffit. Should I try to snake it through the fan hole under the insulation along the ceiling wallboard or over the insulation just under the roofing OSB? I plan to go up to the top of the vault into the clear attic area then over to a side wall vent I will need to install.

 
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Old 12-12-21, 06:14 AM
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One option is to attach your new exhaust hose to the end of the old and as you pull out the old it pulls the new in place. Obviously, this only works if the hose is not attached and has a relatively simple run. I would be prepared for having to work in the attic and run new hose the hard way. If following the old route is too difficult you can go straight up and install a new vent in the roof or a nearby gable end.
 
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Old 12-12-21, 08:55 AM
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The existing fan terminates in a rather crude looking under soffit exit that I really don't like. I like how the other fan I did last year exits on the gable end through a nice double flapper. And it wasn't that hard to remove some siding and cut it to fit snugly around the outlet. Straight up is not an option in this case, I can't even see the fan enclosure from the attic, its on a vaulted ceiling section that parallels the roof by only a few inches.
 
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Old 12-12-21, 02:42 PM
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I plan to go up to the top of the vault into the clear attic area then over to a side wall vent I will need to install.
In a perfect world you want to have the new vent insulated and pitched to the exit vent. Install timers to the exhaust fan so that all moisture is well ventilated, with that your good!
 
 

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