Duct Booster Fan Question from Steve

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This is an email conversation I had with Steve who contacted me through our website about installing a duct booster fan. The first email was sent to me last year.

Question: What brand of in line duct fan and pressure switch did you use? This is exactly what I want to do!

Answer: The 12 inch duct booster fan came from Aero-flow. The pressure differential switch came from my local HVAC supplier. At the same time I ordered the fan, Aero offered a rheostat that would allow variable speed operation. I wired the rheostat and a cutoff switch to allow operation ONLY when It was needed. A simple on/off switch could have done the job. Really works good. Any more questions, Please contact me.

Question: Dave, I now have my 12" duct booster fan and pressure differential switch.

1. Could you give me an idea of how you wired this? I have done a lot of wiring in the past. I just want to see what you did.
2. Did you mount the differential switch inside the duct, or did you just run tubes into the duct?
3. Did the duct booster fan need any vibration absorption when you mounted it, or is it pretty quiet?

Answer: Steve,

1. Hot leg of the power through a speed control (with a built in on and off switch) to the fan then to the pressure switch then back to common.
2. Outside the duct about 5 feet before the fan, 1/4 rigid plastic tubing into the duct about 6 inches with a 90 degree turn into the air stream, switch is mounted on a 2x4 and is vibration free.
3. The duct booster fan is inside a duct laying on the ceiling beams. It is quiet.

Question: Dave,

You might remember me. We were exchanging emails on installing an in-line duct booster fan. Throughout the winter I successfully used a sail switch in my cold air return to turn on the fan when the heater ran. Now that summer is here I would like the option to run the fan even if the air handler isn't running.

A picture on your internet site shows a manual override switch next to the dimmer switch. Did you tie that in between the fan and dimmer? What happens when the pressure switch activates and closes the circuit also? Your description below doesn't address this.

Thanks, Steve

Answer: Great. Wire the bypass switch in parallel with the sail switch. That way the circuit is closed all the time and the fan runs constantly.

Should anyone have any additional questions and anything to add about a duct booster fan, please contact me below. Or if you want to read about how I put in a duct booster fan click here.

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