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bathroom fan installation

2493 Views 5 Replies 2 Participants Last post by  Red Squirrel
I'm about to install a bathroom fan that has the fan motor mounted in the vent on the roof. The electrical connection is within the vent housing, above the roof. What's the best way to make this connection?

I didn't buy the Molex connector option. Maybe I should have?

Also, while we're on the subject, I'm gonna install a timer, since the fan's SO quiet. Any recommendations or warnings? I've found these online:
Haven't checked locally, yet.

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To make the connection I would just run the wire along the vent line, under the insulation. Ensure it is very well insulated. Since the motor is on the roof I would insulate that as much as I can from the inside, perhaps "great stuff" sprayed in layers around where the pipe exits through the plywood and tape/staple the pipe insulation on the top of the roof as well (don't use too long of staples!) You don't want any of that heat getting into the attic or you'll get condensation issues. It's a neat concept though since the fan can be easily serviced by going on the roof. Beats going in the attic, like you would if it was an inline fan.

As for the timers, I have the 2nd one you posted, and it works nice. I installed an inline fan a year or so ago along with it. My setup is a bit more complex... the fan is actually in the basement and pulls air from the upstairs bathroom, long run. You will enjoy the quietness of this fan.
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For the connection at the motor, above the roof line, inside the aluminum vent, are wire nuts OK, or so I need something more weathertight?
I'd go by what the instructions say, but wire nuts are probably ok, assuming the junction is in a weather tight containment. To be on the safe side see if you can put it on it's own GFCI circuit. I would imagine the instructions will cover this though, I'd follow that. You did not throw them out right? :p
Nope. I didn't throw out the instructions. That's the .pdf linked in my initial post. The instructions indicate a Molex connector. I didn't buy that with the fans, and am not sure what it looks like, or how weathertight it is.

Am I correct in thinking that if the wire nuts were in the attic, they'd need to be enclosed in a junction box? If the connection is above the roof line, and enclosed inside the aluminum ventilator, is that OK?
Oh my bad, figured there may have been something more specific on the connection without molex connector. Looking at those provided it seems they just pass the wire directly and the housing will install over and act as a junction box. I would be tempted to use a junction box inside anyway though if one can be added and mechanically secured. Ground the fan and junction box. I would maybe even want to use BX wire. I don't know if romex is rated for outside temperatures.

I'd like to hear what the pros say though, I may be wrong in my thinking.
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