We are in the market for a new furnace and air conditioning system and, purely out of curiousity, I wanted to see if I could determine what size furnace our home needs. I downloaded the Manual J Speed Sheet from the www.acca.org website and I have viewed the tutorial. However, I am trying to follow along with the example but I am not able to come up with the same numbers from the MJ8AE table.
For example, for the example "Glass" tab:
*1C-cm, Clear, Single Pane/Storm, Operable, Metal no break, fixed Horiz. Blinds at 45
U-Value: 0.087 (Why? From Table 2A I would have used 0.87)
Cooling HTM (N, NE/NW, E/W, SE/SW,S): 16, 33, 46, 40, 24
(Again, why? From Table 3A-1 I would have used: 26, 46, 61, 54, 35 because the Design CTD is 21).
*1E-c, Double Pane, Clear, fixed Horiz. Blinds at 45, rounded CTD of 20
U-Value: 0.560 (I agree with this number).
Cooling HTM (N, NE/NW, E/W, SE/SW,S): 13, 30, 43, 37, 21
(Why? From Table 3A-1 I would have used: 16, 33, 46, 40, 24)
Any assistance you may be able and willing to provide would be greatly appreciated.