Hi, I'm a new poster here and I have an extensive HVAC system that uses inline duct fans. I'm using SunCourt at present but will soon be upgrading to the quieter and more powerful vortex fans sold
here.
My automation system is an X10/UPB hybrid controled by HCA. I have two zones in my ranch style house and the duct fans sit on 2 8 inch feeds between a split plenum which was moved to the center I-Beam to facilitate a soffit-free basement plan that consists of two offices and a library.
My Furnace is controlled by a UPB UMI32 I/O module made by SAI. One of the inputs is controlled by a relay attached to my blower output and is used to convey the on-off status of the system. The outputs are currently used to control the AC and Heat request lines but I'm thinking of re-deploying these. I have a TempLinc in the master bedroom which is used as the secondary thermostat.
Since cold air is denser than warm air, the automation system runs the inline fans at 66% during the cooling season and 50% during the heating season. On especially warm days, when the system hasn't cycled off in 4 hours, the automation system will switch to "max ac mode" and run the inline fans at 100%. This really improves performance. At night, the inline fans are not run which increases plenum pressure in the bedroom side of the main plenum.
I highly recommend the use of inline fans over damper systems as a component failure cannot cause a corresponding furnace failure as has been described above. I also recommend UPB over X10 due to the reliability improvements. You don't want noise to command the AC and heating components on at the same time!
I'm thinking about simply adding a seperate thermostat to the bedroom zone and using my 2 switched outputs to simply control power to the respective zones. This will prevent having to depend on X10 to provide thermostat signaling (and free up my K housecode as an added benefit).
Anyway, hope this post helps!