Where to locate bathroom fans?
tupchurch
| Posted in Mechanicals on
I generally place a bathroom vent over a shower. I have read some different lines of reasoning and had a HVAC sub tell me he only places a fan over a shower if it has a heat lamp. I only feel a draft from my shower fan when the glass door is opened because presumably when it is shut the air is only moving over the top of the glass wall. Hard to sort out myths, assumptions of leaky envelope, etc. Plus, I don’t know enough nerds who I can even as questions about building physics. My loss.
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Replies
tupchurch,
The advice usually is to locate it in the shower. I'm not sure it makes that much difference to the moisture captured if it is right outside the enclosure. The problems come from when it is so far away that the moisture has a chance to disperse.
Fans in the showers is something you need in older leaky homes where the bathroom was typically colder than the rest of the house. There any moisture that made it into the walls could cause mold.
In newer high performance build, the interior surfaces are warm enough that you should not have condensation issues (if you do, crank up the heat in the bathroom, in a new build resistance floor heat is your friend).
There I like to put the exhaust fan above the throne, this puts it close to where you want to exhaust air and also lets you get the shower area nice and hot when in use.
@Akos,
I've been dreaming up the vent system of the bathroom for my next build. I think you'll appreciate this:
For bathroom ventilation I expect little air movement when you have vent only with the door closed (I haven't formally tested this). I don't undercut my doors, so I posit getting good movement includes both a supply & vent. So I'm planning to have a smaller dedicated HRV to provide supply down low, and the vent up high. To which the location of the vent shouldn't matter so much because you should but getting good movement and exchange of the entire bathroom. but I agree, over the throne is best because that's the worse of the two for IAQ and usability.
Thoughts?
P.S. More to that thought of usability, its more of a space design thing, I think separating the shower and the toilet to different rooms or spaces I think significantly improves usability, especially with multiple people for one bathroom.
Jamie
I usually put them near the shower but not in the shower, and located so they also serve their other function as a "fart fan."
Has anyone looked if the fans are actually rated to be "in" the shower? I know the lights have to be rated to be installed there, but I've never checked on the fans... If the fans aren't rated for installation over a shower or tub, then installing them in that location is not an option.
Bill
Bill,
From Broan's website:
"Products that have been Listed by Canadian Standard Association (CSA) or Canadian Underwriters Laboratories Inc. (cUL) for use over a tub or shower may be used in this application. These products will be marked as "acceptable or suitable for use over a bathtub or shower when installed in a GFCI (Ground Fault Circuit Interrupter) protected branch circuit. Click the product Specification Sheet on our Website to confirm."
Another option (don't know how large your bath is) ... vent over the shower AND the toilet, both duct-ed to a single remote fan unit.
There are these videos about bathroom fan placement from Corbett Lunsford on his Home Performance Youtube channel.
https://www.youtube.com/watch?v=YAi9rJ31wqU&t=251s
https://www.youtube.com/watch?v=fqwYFduOK_Q
https://www.youtube.com/watch?v=DjeOhCfOhO4