Bathroom Exhaust Fans

Started by Redoverfarm, December 11, 2008, 02:13:44 PM

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Redoverfarm

Anyone installed one of these?  If so what type of vent pipe was used metal or plastic?  The one that I have is a Broan w/4" outlet.  It is a 70CFM fan.  I thought the amps were a little high at 22.  Was thinking of dryer vent pipe but I am not sure because of the moisture and metal.  Maybe PVC would be a better choice.

MountainDon

I've used aluminum flex duct. The original in our home was the same with a fiberglass sleeve
Just because something has been done and has not failed, doesn't mean it is good design.


glenn kangiser

I was sold aluminum flex duct with the one I got.

That fan should be no more than 2.2amps,  not 22, unless it has a heater also.
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Redoverfarm

Didn't have my extra set of eyes on so you are probably right.  Thought that was strange but couldn't find my glasses.  Probably threw them in the fire with the saw dust.  I hate going blind at such a young age. ;)

brian_nj

Metal is the preferred method of running the piping, in a lot of areas it is even code. a couple of suggestions. First if venting out a side wall try to angle the vent down a little twords the outside to allow condensation to flow out of the cabin. Second Insulate the pipe this can be very important if the pipe is run between two floors (in the ceiling) to avoid condensation build up. And finally if at all possible go out a side wall rather than a roof. Over the years I have  seen many more problems with vents that terminate through the roof than those that are side wall vented. Plastic pipe is useless it tears to easily and if you are in a hot climate it will deteriorate and become brittle in just a couple years.
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glenn kangiser

Quote from: Redoverfarm on December 11, 2008, 11:43:04 PM
Didn't have my extra set of eyes on so you are probably right.  Thought that was strange but couldn't find my glasses.  Probably threw them in the fire with the saw dust.  I hate going blind at such a young age. ;)

Amps times volts is watts so 22 amps times 120v =2640 watts /746 (1 horsepower = 745.699872 watts)= 3.5388739946380697050938337801609 horsepower appx.  ::)

One heck of a blower.  :)

I need reading glasses for the fine stuff often too. [crz]
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cfabien

Brian hit on a couple important points - sloping the pipe for condensation drainage and insulating it or running it on the warm side of the house insulation.

We moved into a new house this summer, as soon as the weather got cold we started getting water dripping from the fan in the one bathroom. Installer had used the plastic flex duct, well it was completely fallen apart, as well as full of mold/mildew from the condensation, and sloped improperly so some ran back into the fan. Plus they just stapled it up near the ridge vent rather than venting it outside.

I replaced the fans and used 4" PVC drain pipe (the thinwall stuff) to vent it, making sure to come up out of the fan to a high point and then slope down to the new sidewall vent. Then covered the whole works with the blown insulation in the attic. Metal would have worked fine too, but I figured I could glue up the joints in the pvc for a better seal than metal would provide.

John Raabe

Good points here. To reduce friction and efficiency losses smooth wall pipe (metal or PVC) is best. Insulate and drain for condensation control and don't make one of the more serious mistakes - venting directly into the attic. Also check that the backdraft damper on the outside cover works. Some of these are pretty flimsy.
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jbos333

Wow, a 3.5 HP Bathroom fan is probably just what I need to clear out the "fog" quickly! Where can I get one?


Redoverfarm

Well the bathroom fan/light is installed finally.  I decided on 4" alum vent pipe.  Used a dryer vent  wall cap.  I managed to find one that was for siding.  It was already clay colored rather than the regular white ones.  I had to modify it some for the board & batten but was pleased with the outcome.  Besides it had screen installed to prevent the bugs from making it there home. Ended up using three adjustable elbows to get it from the fan to the outside wall.  None were more than a 45 deg turn. 

Had to get a little inventive in that the unit a Broan had the mounts on the opposite side for me to use and the waste pipe from the loft didn't help when trying to box out to hold the unit.  Oh Well another day in the life at the Dogtrot.  Nothing seems to work up there the way it is suppose to.  Everything has a little crook in convientional reasoning. 

I thought I would give it a test run.  Temporary power from an extention cord proved useless.  Using  standard test equiptment in this case it  was a saber saw  ;D . The light portion was working but the fan was not.  I went back and checked the wires and low and behold.  Unlike a ceiling fan/light where the neutral for each were already tied together this unit was not.  They had a seperate neutral for each.  It was hidden in the housing.  A quick wire nut and it was working like it was suppose to.

I would post a picture but it is not a pretty site.

MountainDon

All's well that ends well.   :)
Just because something has been done and has not failed, doesn't mean it is good design.