I'm a homeowner that installed one of your units on a HVAC unit with heating and cooling, it must be about 7 years ago...or whenever it was that oil was about 60-80 cents a gallon. I've never had a problem with your Fan Handler (other than sorting out the original wiring details and finding a good place to mount it), and I rave about it every year, in amazement about how comfortable our home is...and why it is! A quality thermostat (in my case, a Honeywell electronic with fuzzy logic) teamed up with your fan controller is a great combo. I really appreciate the quiet ramp-up and ramp-down of the fan speeds in accordance with plenum temps. As a building official in CT, years ago I saw a lot of low-end single speed (and possibly oversized) mobile home hot air furnaces installed in closets adjacent to living areas... with cheap thermostats, resulting in temp overshoots and a lot of fan noise, and felt sorry for the occupants. Sorry that they didn't have your system installed.
Thanks for all the comfort I've enjoyed... all these years!