Step 1: Determine the size of exhaust fan. To choose the size of the fan needed you will first calculate the room’s volume and figure out the activity going on in the room. The chart below gives examples for CFM (Cubic Feet per Minute) of air that should be exchanged in a room based on room uses. (For a much more detailed chart and formulas see the pdf in my resource section for the American National Standards 2004.) Here is a simplified explanation on determining the size of fan you need. This information comes from: https://www.grainger.com/content/supplylink-how-to-choose-the-right-exhaust-fan
“Once the fan type is known, the volume of air exchanged must be determined. Your local building codes should contain information pertaining to the suggested air changes for proper ventilation. The ranges specified will adequately ventilate the corresponding areas in most cases. However, extreme conditions may require “Minutes per Change” outside of the specified range. To determine the actual number needed within a range, consider the geographic location and average duty level of the area. For hot climates and heavier-than-normal area usage, select a lower number in the range to change the air more quickly. For moderate climates with lighter usage, select a higher number in the range.
Use the following formula to calculate the CFM needed to adequately ventilate an area.
Room volume = LxWxH CFM = Room Volume ÷ Min/Change”
My studio is 12’x11′ with 8 foot ceiling. My room volume is 1056′
CFM= 1056’/5=211.2′ (I used 5 min/change in my calculations based on the information in the chart below and from the one I list in the resource section at the end of the article.)
Here’s the chart showing some suggested air changes for a range of room sizes.
|Suggested Air Changes for Proper Ventilation|
|CFM = Room Volume/Min.Chg.||Room Volume = L x W x H|
|Assembly Hall||3-10||Dinning Hall||3-7||Mill||3-8|
|Bakery||2-3||Dry Cleaner||2-5||Plating Room||1-5|
|Bar||2-4||Engine room||1-3||Printing Plant||3-8|
|Beauty Parlor||2-5||Foundry||1-5||Recreation Room||2-8|
|Bowling Alley||3-7||Generator Room||2-5||Restaurant||5-10|
Step 2: Converting a range hood into a studio box exhaust fan. I was lucky and found a brand new exhaust fan in the size I need for my studio. In looking at the other models there I was concerned that I was choosing a loud fan–which I wouldn’t know what the sound level would be until I turned it on. I have since found a handy chart that equates Sones in terms we can relate to easily. My fan is listed at 7 Sones.
The first thing I did was remove the fan housing unit and the fan from the range hood. This step took some time as the fan housing unit was spot welded to the range hood. I had to pry it off.
Then I fit it onto a wooden box that was close in size. I cut the fan housing unit down using a metal snips.
Warning: Very sharp!!
Next I hammered the edges down so that they wouldn’t cut me any more! Using a drill I made 3 holes for screws on all 4 sides of the fan. And taped the edges down with duct tape.
Step 3: Electrical. I won’t show this part, as you should take your fan to be properly wired by a certified electrician. I’m confident in my wiring abilities. (Thanks Dad for teaching me!)
Step 4: Exhaust Flap and fitting the exhaust pipes. Initially I decided to put the exhaust flap on the back of my new fan box. After moving it to where I wanted to install the box I realized it would take up less room if it exhausted through the top. These images show how to install the exhaust flap on the back. I tested the flap to make sure it wouldn’t get stuck open, so I sniped the corners to make it easy to open and close.
Once my fan was ready to install I had to choose where to put it. I put it in an area of my studio where I have a kiln and where I tend to use solvents and chemicals. My ideal placement was changed a bit once I realized a stud in the wall was in the way…and then it was time to cut a hole in the wall! Eeek!!
Yes that is a hole in my studio wall. I got a bit nervous at this point!! But I pressed on.
The helpful employee where I bought my stove fan sent me home with a variety of exhaust pipes, so with my handy metal snips and very careful measuring I got all parts put together.
In conclusion: I wish I’d added an exhaust fan to my studio years ago! An open window is not enough to properly ventilate an art studio. (By the way, the window beside my fan does not open. The window I can open is across the room so I am hoping for a good exchange of air.)
Chart to refer to for CFM for art studio listed on page 7. Table 6.4 https://www.ashrae.org/file%20library/doclib/public/200418145036_347.pdf