New Construction

[Johnny-B]

Started building new house and are looking into my air-conditioning needs. My house is 2200 sq feet, energy efficient windows and doors, and insulated everywhere. I have a very reputable contractor who is installing equipment. He said 3 1/2 tons will be fine. I live in an area with very high humidity and 100 degree days in the summer. I'm wondering if I should go to a 4 ton unit, I want this house to stay 74 to 75 degrees in the summer even if it is 100 degrees outside. I am a A/C tech but deal with chill water systems, and building controls. So I am kind of lost when it comes to the new high efficient units that are being used today. Would 3 1/2 tons be fine are do I need to go to the 4 ton and it will just cycle more?

[phbsales]

Did your contractor do all the load calcs and duct sizing calcs and review them with you? Off the cuff, it seems reasonable.

[dash]

Likly three tons , max. Get a load calc., Manual J from www.acca.org

Oversizing will not provide comfort,it will reduce dehumidification.

If you can't find someone local ,look online,to send your plans off for a Pro load calc., and duct design.

[BaldLoonie]

How well are you building the sucker? If I was doing it, I'd foam it and make her good & tight. Then probably need a 2.5 ton and have a very low utility bill. But even decently built with conventional insulation, 3.5 ton sounds a bit high, 4 ton worse.

[REP]

I have advized hundreds of home builders in an attitude when having a house built.
The number one thing is to pay attention to those things that will pay you back after the house is built.
Number one of course is insulation.The bettor the insulation the more it will save you on operating cost of owning a home.Look into foam and have an expert explain the techniques to you.
Then comes windows and doors.Here again the bettor the items the more it will save you.
The next thing is things like ceiling fans and bathroom fans and stove vents.All these things come with energy star ratings,the only trouble is you have to ask for them and they do cost more than what the builder will normally use.
Then of course you would be crazy not to have a load calc done and a manuel "D" duct design done.Why install a 3 1/2 ton a/c if all you really need is a 2 1/2 ton.
I have to say,all my suggestions will cost more than the standard equipment that a typical builder would use,but everything I have suggested will pay you back in savings.Nothing else will.Not the granite counter top or the amazing shower stall or the sunken living room. You have the oportunity to do things right from day one,do not be penny wise and dollar foolish.

[genduct]

[QUOTE]Started building new house and are looking into my air-conditioning needs./QUOTE]
Isn't it interesting that you have begun to consider the AC AFTER you started building
This seems to be the root of the problem, AC is th redheaded stepchild, who becomes the after thought. You need to get the loads/ CFMs and figure where the duct goes NOW! Not after it's framed and you find yourself dodging high hat fixtures and other "significant" architectural features.

[Todd S 2]

Is the home a 2 story or ranch? How will it face; i.e. south, east, west or north?

Basement or crawl space?

Gas furnace, electric heat, H/P or A/C?

[paul42]

North Central Texas, 4,000 sq. ft. - 2 ton.
I keep my house at 74 degrees in the summer.

Shade the windows in the summer.
Put the duct work and air handler in conditioned space.
Make the house nearly air tight.

Build it right to start with, save for the life of the house.

[basshound71]

600 sq. ft. per ton will do it if insulated well which would be 3.66 tons. 3.5 will be sufficiant. This will allow for good humidity control and the temps you need. If insulation is any less than great then go with a 4 ton. I use these calculations in Memphis, TN which has very similar temps to DFW.

[basshound71]

2 tons with 4000 sq ft in North Texas? Think you better look at your model number again.

[leander311]

2 tons with 4000 sq ft in North Texas? Think you better look at your model number again.

Agreed, Paul would love to see your house! This would be quite impressive even for 6pcf spray foam insulation, cool roof, ideal shading, etc.

[beenthere]

2 tons with 4000 sq ft in North Texas? Think you better look at your model number again.

His house was built to be energy efficient.

[paul42]

My 2 ton Trane heat pump will keep my house at 74 degrees on a day when it hit 108 outside.

There is no doubt concerning the model number.

Again, shade all the windows in the summer, put the hvac system in conditioned space, and make the house nearly air tight.