I’ve been considering putting an inline duct fan in my own home to some new duct work that is heating and cooling a new room over the garage. The room does heat and cool ok, but not nearly as well as the rest of the rooms on this system. So I just want to give it a boost. Of course, since the house was built with only one central return in the hallway on the second floor, it is most effecient when the doors are left open. I do hate that part about the system. I already know that many don’t recommend these fans, but I can’t afford to replace my whole system at this time. It’s 14 years old and I know that at some point in the next few years I’ll be forced to, but not happening now.
Anyhow, I’ve read quite a bit on the different ways of activating the inline duct fan. One of the methods I seemed to like was to use the 51 Aprilaire Current Sensing switch, however, it’s installation instructions tell you to clamp it to a common wire from the blower motor. I don’t see a common wire coming from my blower motor. It is a Trane system. The blower motor only has a black wire to the run cap and then another black wire to the motor, a yellow wire from the motor back to the cap and then a red wire to one of the speed terminals on the fan. If I use this method, I’m not sure on which wire to clamp it to since neither are a common wire.
I’ve also looked at using a small 24V relay to tap into the voltage from the thermostat wiring or a sail switch. I’m hoping someone looking at this can give me some good adivce on the pros and cons of each method and perhaps even recommend the best fan to use. I think Lowes has one for about $35 that’s a little over 200 cfm’s.