Our 19 year old original ac unit is on its way out. It runs constantly during warm weather. House is 2700 sqft center hall, r40 in the attic, new windows, not sure about wall insulation R. Anyway I had 3 firms come in and give me quotes. Original unit is a 4 ton, 10 seer unit, running at approx 8 -9 seer (i assume). First company said 4 ton is correct, he measured all rooms and I assume did a schedule J and spent over an hour at the house. 2nd firm said I need a 3.5 ton unit, just went off of the total sqft of the house. 3rd firm said the current unit is undersized for our house and we need a 5 ton unit, he was in and out. So who the heck do i believe? BTW the first firm quoted me an installed price of 5500 for a 14 seer lenox and 6800 for a 15 seer 2 stage lenox. i almost fell over. 2nd company quoted trane and the price was the same for a 14 seer but its a 3.5 ton. 3rd firm didn't get back to me yet. Are these prices outrageous or inline with what i should expect? what seer should I get for a NJ climate? We plan on staying in the house for 10+ years. Is lennox a good brand? Any rec'ds on brand or anything else I need to ask to figure out the correct size? I know this is a bit off topic but you guys always come through with valuable info.