ken

if an accurate load calc, I don't want to be borderline in Houston, Texas. Go up to a 3 1/2 ton on a good sgl stg condenser or a four ton on good two stg condenser.

I do not like the idea that Trane has to rely on third party coils for the larger tonnage units. Shame and embarassment on Trane!

IMO

The unit is 12 years old. 2006 was the square footage of the house.

I would have preferred a 3.5 ton unit, but Trane has either a 3 or 4.

Though I would have liked a all-Trane system...unfortunately with the Tax credit I have to lean towards the Aspen Coil.

I'm leaning towards thr 4 ton...just wondering whether it would doo many short cycles...and there by not doing a decent job on reducing humidity with the variable speed.

ken

ask dealer about the XR15 tax credit qualifying condenser to see if there are any applicable ssystem that would fit your home in a 3 1/2 ton.

IMO

I like the fact that your dealer did a load calc--shows he cares. He's right that the 3 ton should do the job most days, but if the load calc is 100% accurate, 3 tons won't always do the job on the hottest days of the year. The output on the 3 ton setup is 35,600 btus. How much it "won't do the job" I can't tell you. Could just be talking about a few degrees warmer in the house, if you can live with that. But depending on the latent and sensible breakdowns of your calculated low, could be worse, since the capacity is derated as ambient temperatures increase.

I don't think the 4 ton would short cycle, not on low stage. And with the TCONT900 thermostat and communicating system, controlling humidity should not be an issue with the 4 ton unit, since it can run longer cycles in low stage at a lower airflow.

See what your contractor thinks. Explain the fact that the 3 ton system won't always be putting out 36,000 btu's.

The contractor has been very patient and we have spent over 2-3 hrs on the phone in the last week or so.

Its at the point that I need to make the call.

I'm also have copies of his load calculation...though I have no way to attach it to this thread.

Ken,
Be careful. If you recall, Houston saw many many 97-100 degree days last summer. Depending on what your contractor used for design temp it was probably 94 or 95 unless you're on the coast (lower there). Your peak load will be around 4 pm, usually. No way I'd put a 3ton unit on my house based on a full 3 ton load calc @ 94-95 degrees. It's unfortunate Trane is using the Aspen coil. You won't be impressed. Lightweight cabinet and also a 'box' coil for horizontal application (attic install) therefore harder to clean and a higher static pressure than a flat, slab style evap coil. The sweet taste of your $1500 tax credit will be long gone and the sour taste of poor quality will remain.......You can get about $600 or so tax credit w/ the all Trane system. Ask your dealer about the main circulating fan credit. Good luck.

dougl99, can you elaborate more on the $600 credit? Circulating fan credit?

Any links?

I couldn't get the link from the energy star site to copy. google main circulating fan credit. Here's how it works on qualifying furnaces.
installed cost of furnace x % of cost attributable to fan x 30% federal tax credit up to $1500.
The manufacturers site will have the % for you. Generally, 45-55%. So, if the furnace was $4000 x 50% x 30% = $600. The credit gets little play, but many homeowners purchased qualifying furnaces and don't even know it. Electric heat air handlers are NOT eligible. This credit is NOT the 95% gas furnace or 16seer/13seer A/C credit, but the total for any and all credits is $1500.

doug199 -
your last post was interesting. I wasn't aware of that. Going to check it out.

I am afraid 3t is going to be a stretch unless the windows are high quality and everything is sealed up and tight. I used to have a 3.5 builders grade with horrible ducts and nominal insulation in a @1700sqft ranch. I went to a 3 ton 15 seer Ruud after reworking and sealing the duct system and taking the insulation past r30 in the attic.