Hello. I have a pretty large home (about 3500 sq. ft.) with two A/C units. The one that cools the downstairs needs replacing. I live in super-hot Dallas and we have lots of glass, plus kids who leave the doors open all the time, so I am going with a 5 ton unit, gas furnace. Problem is, the pricing is all over the place, some with high pressure sales tactics. Can someone tell me objectively what is a fair price to pay for a high (15-18) SEER unit, installed? (Ductwork extra, I understand). I would choose a quality product like Goodman, Trane or Lennox.
First be careful about oversizing your ac unit. An oversized unit will cool the house, but won't run long enough to dehumidify.
You asked about an objective price. That's dependant on brand and all the bells and whistles you want.
If it was me I'd purchase a Lennox G61MPV and a 15 seer ac. G61 because it is a 2 stage gas valve meaning it will fire on low fire and after a period of time if needed it will kick into high fire to finish. It also has a variable spped motor which is controlled by dc voltage. Very nice and and not as noisy. 15 seer because it is still a single stage compressor and not as complicated or expensive as the 16-21 seer ac units. Pricing for what I described really depends on the area. At my company, it would probably be around $10-12,000 if you go with a higher seer you will definately need the variable speed motor and pricing wil be anywhere from 13-15,000. Unless you get a goodman which I wouldn't do(up here we call it good junk). Trane is ok except trying to clean the outdoor coil. It is a shreaded aluminum coil and once impacted with dirt you will have to uncase the coil and use an acid based coil cleaner. It's a bad time.
You should also consider a good filtering system if you are going to spend the money.