Harmon Ff1500 Blower fan

I have a Harmon SF 1500 The blower Is rated at 1000 cfm but barely makes it thu my heat ducts . It’s an add on to my Propane furnace. At first I thought the heat was being recirculated thru the returns so I plugged them and still got very little velocity at any register. does anyone know if you can add a larger fan moter presently the moter is 1/5 hp. I would rather not put booster fans on the ducts.


Jim

Jim,

Did you find any answers to your problem yet?

You would most likely need an 1800 cfm fan, but I'm not sure what modifications can be done to that furnace. Simply increasing motor hp does not translate into more cfm's. Your issue is more complicated than that unfortunately.