Thanks for all the input.
I thought I was getting down to the end of my estimates but now I guess I have to keep going.
I have a guy on his way over now & I will ask him how is is coming up with the size and request a load calc. I also scheduled Public Service (Out Gas & Electric provider) to give an estimate on the upgrade. I would hope that they would do a load calc and not just wing it. I will let you know how that goes.
There are 3 other houses in my neighborhood that are the same model built the same year - 1989. Two of them have had their HVAC updated in the last couple years, I understand that they may have been oversized but I am going to visit them later today & see what they had put in and their feelings on how well they work for them.
This is a 2 story house: zone 1 1st floor, zone 2 2nd floor. Insulation was R30? in the attic - About 6 inches of blown in insulation between the rafters? Never been upgraded but has compressed a bit over time.
@Beenthere - you asked:
"On the coldest nights, do both of your furnaces have to run 24/7 to maintain the temp you set your thermostat to? Or do they still only run for a few minutes each."
The best answer I can give is: We run Zone 1 during the day (family room & kitchen) and Zone 2 (bedrooms) at night. In the winter we set the zone we are not using to about 58-60 then a couple hours before bed it changes to about 68. Zone 1 at bedtime goes down to 58-60 and resets to about 68 a couple hours before we wake up.
So it would be rare that both systems are on at the same time ever but I guess on the coldest of nights, zone 1 could run at night to maintain 58 degrees.