So, I had Chipotle last night and this morning got to thinking…
Is a bathroom exhaust fan more effective with the bathroom door closed, open, or cracked?
Let’s make three assumptions:
- The purpose of the exhaust fan is to remove offensive odors from the bathroom. Removal of humidity is neglected.
- Efficacy is defined as the ability to quickly and thoroughly reduce offensive odors in the bathroom.
- Offensive odors must be removed through the fan; there is no “credit” for odors that waft into connected rooms.
Here are my thoughts on the various configurations:
Closed: The fan is pulling mostly bathroom air. However, the door closed increases the pressure drop of the system, so less air volume is moved. The most common airflow path of door gap on the bottom and exhaust fan on ceiling, decreases the amount of “short circuiting”, ie. outdoor air moving directly to the fan without displacing odoriferous air. But, could this cause stagnant “dead pockets” of odor?
Open: The fan can pump more volume, but if unpowered, odor can easily escape to the connected room. There’s also increased short circuiting.
Cracked: More volume moved than a completely closed door. However, there’s enough of a flow restriction so that odor will not preferentially seep to the connected room. Also, allowing air entry from the multiple edges of the door could “fluidize” the odor and reduce stagnant zones. Perhaps the best (or worst) of both worlds?
I’ve considered doing a home experiment, but I presume the girlfriend would be unwilling. I’d also have trouble creating a controlled environment, due to variations in bathroom volume, exhaust fan flow, and digestive fauna. I have a Lab mix with a keen sense of smell and chicken allergy, but I haven’t quite figured out how he could contribute.
Surely, anecdotal evidence from other perceptive Dopers exists. If so, please share.