Gonna do some drywall work in my parents bathroom. The vent fan that is there vents to an open, but sealed area above the bathroom vanity (mold heaven probably). There is no way to vent out the roof without going through their bedroom upstairs, so we are thinking of venting straight out the side of the house. There is no soffit, the roof runs down to the side of the house and only sticks out enough inches to tuck a gutter under. pretty straight forward, but the question of cold air drafting back in through the fan came up. is there a damper or any type of thing to prevent air from drafting back in through the fan? never done a vent fan before.
How to prevent draft from side exit bathroom fan?
- Thread starter Sh40674
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mrramsey
Well-known member
Typically there is a damper (plastic flap) on the fan exhaust. When you vent through the wall you will use a vent like a dryer vent termination.
Blue XJ
Well-known member
Our vent fans all go out the side of the house. They all have dampers on the exterior part to prevent wind from coming in, and the pipe running from the fan to the vent are all insulated as well to prevent condensation. I don't notice any cold air coming back in through them.
glend123
Well-known member
Is this in a bathroom with a shower? Are you in a cold climate? If so, my experience has not been good trying to find a vent that doesn't flop around in the wind (it was next to our bedroom and kept us up at night) and won't freeze up in the winter with the steam coming from the shower. Also had bees make a nest in there. I capped it off and put it back into the soffit where the builder originally installed it.
I ran ours out the floor and then out a basement window. The fan is in the basement. I put an 8inch PVC pipe up the wall with the intake on top. Put towel hooks on the pipe and painted it. Wife likes it.
In the winter I unhook the vent from the window and let it dump in the unfinished basement.
In the winter I unhook the vent from the window and let it dump in the unfinished basement.
Boilerhouse
Well-known member
We have a bathroom on the main floor (2 story farmhouse) which vents through the side wall. There is a flapper on the vent at the wall, and another flapper which came with the fan. The vent is on a north wall, and we get temps of < -30 C. I can't really say that back drafts have been any sort of an issue.
larry4406
Well-known member
I had to install a Broan fart fan in a side wall of a bathroom vs normal ceiling install. I called their tech line. They told me to remove the flapper in the housing as it would no longer function in a side wall application (....my concern exactly and cause of call..). Then use a wall cap with a gravity flapper. Done.
If you're in a cold climate and the duct goes through the wall down low (basement), yes, cold air will backdraft through the duct/fan. This sounds like your situation.
For some people a good wall cap with flap/spring/gasket will be good enough.
The best setup is an in-line backdraft damper. Google aldes backdraft damper for a picture and source. These have a spring and gasket and are very effective. They slide in to the inside of the duct.
We sell them but unless you live in Alaska you're better off just going on the web.
For some people a good wall cap with flap/spring/gasket will be good enough.
The best setup is an in-line backdraft damper. Google aldes backdraft damper for a picture and source. These have a spring and gasket and are very effective. They slide in to the inside of the duct.
We sell them but unless you live in Alaska you're better off just going on the web.
Voi
Well-known member
Timely thread and information for me. I need to side vent an exhaust fan at our cabin before insulation and sheetrock.
this thing is awesome. just watched a video with a simple box fan on low made it open. nice. this with a gravity operated cap outside would be perfect.
i suppose i'm confused now.. i was looking at a couple models that are straight through the wall.. cut the hole right through the house and install. no biggie.
i see the ceiling box style is much more common... how do i vent these? the way it's built you have no choice but to go up or down... not straight out? how do i do the duct? we didn't want to tear walls open
this style:
https://www.homedepot.com/p/Delta-B...-Ceiling-Bathroom-Exhaust-Fan-SLM70/204347757
i see the ceiling box style is much more common... how do i vent these? the way it's built you have no choice but to go up or down... not straight out? how do i do the duct? we didn't want to tear walls open
this style:
https://www.homedepot.com/p/Delta-B...-Ceiling-Bathroom-Exhaust-Fan-SLM70/204347757
basically my goal is this, in the bottom left picture... so how would i do that with one of the above styles?
http://tribunen.com/31948/cosy-bath...-wall-and-soffit-venting-options-build-nobby/
http://tribunen.com/31948/cosy-bath...-wall-and-soffit-venting-options-build-nobby/
pardon my third shift insomnia and overthinking lol..
so i'm thinking this:
https://www.homedepot.com/p/Broan-70-CFM-Through-the-Wall-Exhaust-Fan-Ventilator-512M/100662377
whichshould have everything i need, and adding one of the butterfly style dampers mentioned above as well
if i went that route, should seal any backdraft, shouldn't it? the reviews for this fan are good, but a couple say they still get a little backdraft
so i'm thinking this:
https://www.homedepot.com/p/Broan-70-CFM-Through-the-Wall-Exhaust-Fan-Ventilator-512M/100662377
whichshould have everything i need, and adding one of the butterfly style dampers mentioned above as well
if i went that route, should seal any backdraft, shouldn't it? the reviews for this fan are good, but a couple say they still get a little backdraft
70 cfm is on the low side for a bath/shower vent.
I have been using fantech fans in all my projects for most of the last 20 years -- they make an exterior wall mount fan that's a favorite -- easy install and powerful. I use the inline model in attics -- both work great and no noise.
Fantech makes nice inlet grills -- I typically use two w/ "y" to the unit. One in shower and the other by the toilet.
The company that makes the original "dryer box" -- now makes a very nice exterior grill .. I have been using it for dryers and bath vents.
It's not the cheapest way to go -- but it's the best IMO.
Panasonic typically gets the top rating when it comes to standard all in one fan units
Fantech makes nice inlet grills -- I typically use two w/ "y" to the unit. One in shower and the other by the toilet.
The company that makes the original "dryer box" -- now makes a very nice exterior grill .. I have been using it for dryers and bath vents.
It's not the cheapest way to go -- but it's the best IMO.
Panasonic typically gets the top rating when it comes to standard all in one fan units
LS6 Tommy
Well-known member
It is a very small bathroom
madison069
Well-known member
A tip I've read was to take those sticky magnetic tape and put some on the flapper. if it's plastic put some on the inside of the duct work so if you put some on the bottom of the outside of the flapper side, it will connect with each other. (This make sense?) Might have to experiment on the size of the magnet you will need to ensure it opens when the fan is flipped on.
Voi
Well-known member
How are these exterior fans for retro-fits, assuming the electric isn't an issue?
I assume just cut a hole for the ductwork straight though siding, sheathing and insulation/sheetrock?
I was hoping to install the duct work for an interior wall mount fan today before insulation and sheetrock at our cabin this weekend. I'm having trouble finding a wall mount fan that is quiet and powerful as I had hoped so I'm thinking about just stubbing that wire outside and installing the exterior fan later on in the project. I can run EMT to whatever height.
tapered-pin
Well-known member
when it comes to single room exhaust fans, quiet means weak.. (i'm just sayin')
Yup.
I recently installed a ducted fan in the attic with (3) 6" ducts going to the ceiling in our master bath. 1 duct in the toilet room, 2 in the main bathroom with the shower/tub, etc. 400cfm and all you hear is a little airflow, fan is suspended (not hard mounted to studs) and is as close to silent as you'll get.
Whenever possible, ill never use a ceiling exhaust fan ever again.
https://na.panasonic.com/us/home-li...ventilation-fans/whisperlinetm-remote-mount-3
All said and done it's not terribly more expensive than a couple high end ceiling exhaust fans. The duct registers with integrated lights are pretty awesome, just looks like a 6" can light in the ceiling.
Sent from my SAMSUNG-SM-G920A using Tapatalk
Diesel Dan
Well-known member
ard
Well-known member
+1000
I've been doing that for 25 years. Don't even need an expensive/quiet 'specially designed' fan. I've made a sheet metal adapter to attach one or two 6" ducts to the input side, mount it in the rafters, exhaust either roof vent or gable/wall vent.
You can get a much higher flow rate, and as you point out barely a whisper
Brian_WK
Well-known member
In my cold climate I have no issues with drafts. My set up is a broan ceiling exhaust fan with the internal damper ---> 2 foot of Pipe ----> wall exit damper. Both of the damper flaps have foam rubber gaskets. I never get a cold draft but it will burp every now and then when someone closes a exterior door and pressurises the house. The exterior damper ill freeze up in the winter below 0f but once you turn it on after a minute or 2 the warm air thaws it out and it operates normally. My buddies that faces north in the country and a much longer pipe between we had to run a self regulating heat tape off of the night light circuit to prevent condensation as well as freeze ups.
Brian
Brian