2 stage scroll compressor vs. one stage?

lenoresNovember 5, 2010

Please excuse this long explanation.

I live in Florida and have a 2465 sq. ft. home. The home is cooled by a 5 ton system and a 3 ton system which are both 10 year old builder models.

The HVAC salesman says that instead of buying two units, the J Manual says that I need 58,000 BTU's to heat and cool, and that it can be done with one 5 ton HP using barametric dampers, a 3 zone control board, 3 thermostats, and a variable speed AH.

The old 3 ton controlled the temp. in two rooms: one 225 sq. ft. and the other 550 sq. ft. The other 1700 sq. ft. 12 foot ceiling is controlled by the 5 ton.

He says that by installing barametic dampers that would limit the amount of air sent through the ducts and channel the excess to the return, I could eliminate a short cycle problem if I install a HP with a 2 stage scroll compressor instead of a one stage compressor. In that way he says the full power of the HP would not be utilized unless it was needed, and my short cycle problem would not exist.

Does this make any sense?

I am so confused. For 10 years I lived with a two unit system, and now I am told that it could all be done with one until. I will be going from 8 tons down to 5 tons, but if 8 tons were unnecessary, than maybe the original system was flawed?

Thanks for your help.


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8 tons sounds like too much for 2400 sq. feet.

5 tons max. Probably could be done with 4 tons. Did you ever notice that the units start and stop alot? Its better to run non stop on your maximum hot days too maintain. This is considered more efficient and better for the equipment. It keeps humidity down too.

Is your place well insulated? How tall are the ceilings? Lots of windows?

What he is saying does make sense. If your in florida, you have lots of humidity. Running longer means less humidity in your house.

Probably makes sense for you to get a 5ton 2-stage. It could run longer and keep humidity down. Those units are very efficient also.

    Bookmark   November 6, 2010 at 11:03AM
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Check out the new inverter heat pump units. Variable speed compressors and fans. Wwwaaayy more efficient and there are tax rebates to help pay for them.

    Bookmark   November 7, 2010 at 8:55AM
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