I have a new home built as of 1 Aug 2012. It is a 4700 rambler 2340 up and 2360 in the unfinished basement. The A/C unit is a 3 ton Bryant, the furance is a 66,000 Input 54,000 Output Bryant with a 3 ton blower and the back of the house faces south. Ceilings are 9 and 10 foot, walls are R19 (2x6), R38 attic and the house is wrapped in Hardie wrap.
The master bedroom is always stuffy and the house won't stay below 75-76 degrees when it is 92 or above outside, the thermostat is set at 74 during the day and 70 at night. I've reviewed the Manual J and Manual D as much as I can understand and it doesn't match what is installed. The Manual J is for a house rotated 180 degrees from mine and is missing several windows on the main floor, a sliding glass door, all windows in the basement and it says the furance installed is a Carrier with 88,000 Input 71,000 Output. The manual J calls for a 2.7 ton A/C.
The Manual D says all supply branchs are run in ShMt, they are really run in F090 Air Connector. The Return Air says it is run in SJSp (I can't figure out what this is) in reality they are run in F090 Air Connector. And my return ducts are only cut about 3-5 inches high 8 inches long but have oversized grills on them to try and quiet them down.
So my questions are:
1) Should the opening behind the grill match the grill size or is a small opening behind a large grill ok?
2) How important is the Manual J / D? Nothing matches and nobody seems to care.
3) I've heard everything from the A/C unit and furnace blower are undersized, to all the duct works need to be redone.
4) I've had the builder and HVAC company out 4 times and they just keep putting bigger grills on the returns and I was told by the owner of the HVAC that he "Can't control stuffy".
I've paid out of my pocket for a new manual J to be done to orientant the house correctly and account for all openings, I'm waiting for the results.. I'm willing to pay for a manual D to be done but since the first one wasn't followed is this worth it? Where do you find an expert in this? Also the F090 specs seem to imply it shouldn't be used the way it is being used, which looks aweful: Sagging, compressed in half, 4-5 90 degree bends on 50 foot runs....
Basically I'm at wits end and I'm not sure where or how to start getting a handle on this.