A/C sizing in New build (new home, water heater, neighborhood)

[ChrisNY]

Hello forum members. We are building a new home which is right at 3000Sqft. After the home was framed we noticed that we will only be getting one A/C unit Carrier 4 ton 14 seer. My concern is that this might not be enough for 3 bed rooms up stairs, open stairwell and the rest of the living space down stairs. The builder Toll Brothers claims they do extensive studies with contractors and the county to size the ac systems. I hate to see one machine never go off while it tries to cool both floors. My guess is that it can cool but will it ever shut off

If anyone has experience with this I would appreciate any feedback

[EricBoyd]

As far as I know, the appropriate or recommended size for an AC air handler is 1-ton for every 500 sq feet of living space. It's OK to be slightly undersized, from what I've been told by my regular AC vendor. One unknown is whether the system they are installing for you will be a multi-zoned system, with more than 1 thermostat and sufficient damper systems to direct air flow when needed. That may be how they get around the tonnage requirements. You might want to have an independent AC company look at your plans and give you some feedback and recommendations, if your builder is willing to make those changes for you.

[Florida2014]

I agree with Eric - I would get an AC company to come by to assess your home's needs. We have a similar home and we have two units (3 ton in the main level, 1.5 ton for the bonus room upstairs, both have separate air handlers with separate thermostats). I know some folks in my community were complaining that their builder did not provide adequate HVAC units in their homes so it may be the same builder.

[Thundarr457]

If you are spending that much you should have a 2 separate zones no matter what the builder says. Once its built there is nothing you can do. We have a 28 year old house 2800 sq feet one level and we have a 5 ton. Get it done right the first time and you won't regret it later. With a 2 story 2 zones is ideal. You better get on this ASAP because they will need a space for another air handler and the ducts may have to be rerouted.

[ChrisNY]

It will be two zones. That's a definite but just one condensor and air handler. 4 ton

[jcmh3]

We have a two-story house that is just over 3000 sf. Our 4 ton SEER 16 unit (single condenser and air handler with two zones) cools the house efficiently and comfortably. I asked the AC company that does our maintenance whether it was right-sized, and they said it was, and there was no need to go with anything larger.

[deeni]

The builder in our neighborhood undersized the AC units and our house could never "catch up." Apparently the entire neighborhood had this issue. We eventually had to replace the unit. Good that you are doing your homework on this so they don't undersize yours.

[Jax2PVB]

I would think if you are going two zone, you should also have two units - that is most common and also extends the life of the condenser bc it is not always working at full capacity. We have three floors and have a 5 ton for each the 1st and 2nd stories and a 3 ton for the 3rd floor finished attic - ours is a bit of overkill, but our house is well built/insulated with the spray-in attic insulation and we pay about $290 a month (yr round avg) for 4900sf for all electric - thats heat/air plus all electric including water heater and laundry for 8 people! We rented first when we moved here and had 2 zones/2 units and paid $310 for 3400sf, plus gas for the water heater, so I think there is a difference, but I agree with the people above that said to have an HVAC company look at the plans. Try Thigpen Heating and Cooling or Creekside HVAC - both of those companies are local and have great reputations around Jax.