I'd like to extend the ductwork to include the sunroom. It's a framed 3-season room with 12" of insulation in the roof, insulation in the floor and the walls are windows from the cieling down to about 18" from the floor.
Can you do a residential Manual-J calc with that amount of window area? Or do you need to do a commercial calc? If I get the load calc software advertised in the top right of this page, then will it be able to calc the sunroom?
The last HVAC guy to look at my system said it was 'Bordering on oversized' but he didn't do a load calc so I don't know who he could tell that. He also said that extending to the sunroom would be fine - but again, with no load calc I don't know how he can be sure.