Wall Vents for Bathroom Exhaust
BrunoF
| Posted in General Questions on
Are there any exterior wall vents available that will seal well and not allow air to escape through stack effect? I hate the idea that I am building a tight house but will have 4 bathroom exhaust fans creating 4 holes in the envelope that could just draft out my air.
I don’t think I want the complexity of an actuated damper, just something other than thin sheet metal or plastic that will just flop around in the wind.
all suggestions are welcomed!
thx
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The broan nutone wall vent is pretty nice. I just bought two of them and they have a light spring close and some decent foam gasket. The flap is bend at an angle so that when wind blows on it it will actually push it more closed. They don’t have an attached tail pipe so you have to add but not big deal. Also famco seams to have a lot of options, some with build in backdraft dampers. I don’t have any experience with those so can’t speak to them but they look nice. Also your fans should have a damper build in for added protection.
also interested in this, or if someone has suggestions on improving existing vents.
both of my bathrooms have 2 exhausts, and when one is on i can feel hot air coming from the one that isnt on :(
all 4 fans have dampers at the fan and the vent itself, minimal duct runs, all insulated, all venting out of roof. the ducts are brand new and a healthy amount of foil mastic tape and some spray foam was used for all connections. have inspected for holes/tears the best i could.
would adding an inline damper help?
I've been using Broan EcoVents for quite a few years now and would recommend them.
https://www.broan-nutone.com/en-ca/accessory/ev100
The hood is insulated and a rigid foam ball rides in the insulated hood cavity. The only critique I have of these is at very cold temps (-10 to -30 C) the ball can freeze up a bit and may require a minute or so of flow to "pop" the ball. I use these both for the kitchen hood and our bath exhausts (3 of them in total). Leakage is so low from the Ecovents, you don't need an interior draft damper at all.
On the kitchen side, I've programmed the EC inline exhaust fan to run at full speed for 90 seconds if temps are below freezing to pop the foam ball in the Broan vent. After that the fan speed is set depending on the induction cook top power level. Although the exterior Broan hood is only 4", I'm still managing up to 150 CFM from the hood, although extraction is very good at 110 CFM. I wish Broan did a 5 or 6" hood with this configuration.
BrunoF,
The Broan model Dennis linked to looks like it would work well. Most vent terminations are designed primarily to prevent back-drafting, which makes sense when you think about it.
In a well air-sealed house the stack effect shouldn't be strong enough to induce a pressure difference capable of opening any damper. Some incidental amount of air may leak through, but remember that in what we consider a house with good air-sealing - say 1 ACH50 - when the wind blows, the entire air inside the enclosure changes every hour.
Some other ideas: Aldes or Tamarack spring-loaded backdraft damper or Tamarack cape backdraft damper hood. Seiho, Aldes, or Tamarack brand vent covers on the exterior walls.
Also, may be too late for the OP, but two alternatives to a bunch of separate exhaust fans are to duct them to an ERV with boost mode or to have consolidated inline centrifugal fans that serve more than one bathroom and which will cut down on the number of exhaust openings in the envelope.
After working with the hvac crew we ended up getting these and have put the required screen in the recess behind the door.
https://dryerwallvent.com/?gdprdisagree=0
@BrunoF - I have one of those for my dryer vent (which was code required but which I don't use since I have a heat pump dryer). It is by far the best looking exterior vent wall vent, although the color choices are limited.
On mine the lid closes with a magnet. Before I plugged the vent, I could feel air escaping from the center of the sides and bottom of the front flap. I cut pieces of very thin adhesive backed foam and put them on the housing, on the same surface the bumper it ships with is placed, which very significantly reduced the air leakage.
Note that the model @BrunoF links to is the better quality version. The big box store also sells a version that looks almost identical from the exterior but does not close as well and is not as well built.
These look nice, if not hard to find online. These are OK to use for bathroom exhaust? Did you guys make the screen or does the manufacturer provide one?
The garage with apartment I built 15 years ago we spray foamed with open cell. The apartment has a dryer and a range hood and we heat with a propane tankless that supplies forced air.
The dryer and range hood vents open up when the heat is on....just saying.
@nynick - sounds like your garage apartment is pressurization is positive and thus forcing the air out the dryer and range hood vent. Although some positive pressure it good, maybe figure out where the makeup air is coming from...and seal up those leaks and try to get all the makeup air to enter via an ERV or HRV.