I'm under contract for a condo in a large building with drop ceilings in the bathroom and no vent fan. I am told that some units have external ventilation capabilities and some don't but I don't know about mine yet. If I'm not able to vent externally, is there any way I could reasonably still install a vent fan? Are there any designed for this situation perhaps? Is it possible that the electrical situation would be a limitation as well?
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You need to exhaust the bathroom via a duct in the ceiling void and through an outside wall. You can't just push bathroom air into the void ... it will cause mold up there and push humidity and bathroom smells into other rooms. To exhaust through an outside wall you'll need to talk to the building manager. You can't be the first one to want this!
Yes it will need power. It's not a limitation. It's just a thing you'll need to do, and you should talk to an electrician about that.
jay613
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The point of a bathroom exhaust fan is to pull humid air out of the bathroom. That humid air must go somewhere.
If that "somewhere" is another interior space, you're just moving the humidity problem from your bathroom to wherever the fan is venting into. If your fan vents into the ceiling space, for example, you'll have humidity and mold in the ceiling space instead of (or, more likely, in addition to) humidity and mold in your bathroom. And no, that will not be a good thing.
If you really cannot arrange external ventilation, your best (and basically only) alternative is to install a condensing dehumidifier instead. Instead of venting the humid air outside, these work by circulating the air through a system that pulls water vapor out of the air (by cooling it down and then reheating it) and then blows the now dry air back into the same space it was drawn from.
The main drawbacks of a dehumidifier compared to a ventilation fan are that:
- a dehumidifier is more expensive to buy and install and consumes significantly more electricity than a simple fan, and also has more moving parts that can break down;
- the dehumidifier may be noisier than a fan (although there certainly are both quiet dehumidifiers and noisy fans on the market);
- the condensed water needs to be drained somewhere (not necessarily a big deal in a bathroom, where it can often just be piped down a drain, but more of an issue in other applications); and
- unlike an exhaust fan, which also helps pull in fresh air through your apartment and into the bathroom, a dehumidifier just circulates the same air already present in your bathroom, making it less effective at getting rid of odors and keeping the air fresh (odor-absorbent filters can help here, if your dehumidifier can be fitted with one).
On the other hand, a dehumidifier has two major advantages over a ventilation fan:
- a dehumidifier can dry the indoor air dryer than the air outdoors, making it attractive in places that experience a humid climate for at least part of the year; and
- most importantly in your case, a dehumidifier can work even in spaces from which air cannot be easily vented outdoors.
Ilmari Karonen
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Others already said you shouldn't dump humid air into your ceiling space or other rooms. As for what to do if you don't have a vent that goes outside...
There are duct free "exhaust fans" but they just run your air through a charcoal filter. That may or may not get rid of stank but it definitely won't help you get rid of humidity. For that you need a dehumidifier. I don't have real numbers on this and I've never tried to size a dehumidifier to get rid of shower steam in a bathroom but I would guess you need a pretty beefy dehumidifier to do as well as a moderately powerful exhaust fan.
If you have a window, put in a fan. If you have no way to vent that bathroom to the outside, I'd personally avoid that apartment, there's probably other stuff along the same lines you'll have to deal with. But I don't know if you have the freedom to make that kind of choice.