Oops, ya I meant 1600 CFM. For the room, I have 2.5 inches of closed-cell spray foam (around R 19 I think) and will have R49 blown-in insulation in the attic. I am in south-central Iowa, so we do get some pretty cold winters and hot summers. The furnace is HE, so the end output is 76,800 BTU.There is no way an 80,000 BTU furnace can move 16,000 CFM.
That’s a huge furnace for such a little room. Huge amount of air conditioning as well.
What sizing calculations have you done?
I should say, my "calculations" were more just using several online calculators. In hindsight, I should have done more research but it was selling for cheap and I didn't have much time.
I used a load calculator like this one and came out with 60k BTU furnace
I figured that since the furnace is downdraft and the ducts will be below the floor in a closed-off but not heavily insulated area my furnace being slightly larger would be ok.