Electrical Wiring in the Home/Furnace Blower


I'd like to use an old furnace blower as a air filtration in my workshop.  It has a capacitor and 4 speeds, hi, med hi, med low, low (black, yellow, orange, red) along with the white common.  I'd like to have to hooked up to one switch to select from those 4 speeds ad then add a timer to that line so it can run for a while after I leave the shop after working on a project to clear the air. Is that possible and if so what kind of switch and how would it be wired is my dilemma.  Any help would be appreciated

You are looking for is a rotary fan switch. There are also push button switches, like for a ceiling or whole house fan.

They come mostly in 2 and 3 speeds. If you need the fourth speed you will be looking at a specialty switch or getting a little more creative.

For the timer; You can put the timer in line with the power going to the switch. Intermatic makes one with a hold option. Or you can just go with a wound type timer, or you can wire in a switch that bypasses the timer for those times you want to keep the fan on. Then you close the switch and turn the timer to run the fan for the amount of time you set the timer for.

After you decide which way to go if you need help with the wiring aspect let me know.  
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Electrical Wiring in the Home

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Greg Hughes


Troubleshooting electrical including appliances and HVAC.


34 years of experience.

Both college and tech schools in this field.

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