Questions about one inline exhaust fan serving two bathrooms
My floorplan has two bathrooms very close to each other, and I am planning to use a single inline fan to cover both exhaust jobs. Here are the details…
One bathroom is 90 sq ft plus a walk in shower that measures 3.5 x 7.5. This bath is long and narrow,15 x 6′ (not counting the shower) with the entrance to the shower on one end of the long side and the toilet on the opposite end. The other bathroom is small, 40 sq ft. Total square footage is 156, including shower, and with 9′ ceilings means the total cubic feet is 1406. If my math is right, I need something in the neighborhood of 187 cfms to get the recommended air changes per minute. Both baths are near a gabled end of the house, so duct runs will be short. I will be doing the ductwork myself to ensure the ducts are as efficient as possible with as little friction as possible.
Here are the questions…
I was considering a WhisperLine fan, and it seems that the CFM options are 120 or 240. I assume the recommendation would be to step up to the larger fan to allow for a little pressure drop from the ducts, or would a 120cfm fan be close enough? It looks like it is a difference between 10 and 5 ACH.
I assume it is possible to have multiple on/off switches for the same fan? What about the timer delay? Can that be triggered in multiple locations, and the delay would reset if the timer is triggered from one location and then triggered again from the other location?
For the bath that is long and narrow, do I need two exhaust ports, one near the shower and one over the toilet? Adding another port means more ductwork and fittings, which adds to the total friction, and a more complicated design, but it might help balance the exhaust to more evenly match the square footage of the two bathrooms.
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