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  1. #1
    Join Date
    Jun 2008
    Location
    Houston, Tx
    Posts
    4

    Question Dual Stage Compressor in Houston Texas a waste?

    In Houston, Tx, our seasons are Summer, Summer, Fall and Spring.

    Would it make sense to go with a Trane two stage compressor unit like the XL 16i or would it just run on high all the time anyway so that an XL 15i would be just as good a choice?

    Do the dual stage compressors break more often?

    Would the additional cost really pay for itself over the typical 3.5 year window in this climate?

    Thanks!

  2. #2
    Join Date
    Jun 2004
    Location
    4H: Hot, Humid Houston H.O.
    Posts
    3,304
    I have the A-S version of the XL19i on the southeast half of my hours. This model runs 1st stage about 55% of full capacity (while the XL16i is 65-70%). No way does it run 2nd stage all the time like you are worried about. It turns out that my house can be held *close* to setpoint using just the 1.7 ton capacity of a 3-ton unit, my surprising experience is extremely long runtimes on 1st stage with only occasional resort to 2nd.

    This is a 3400 sqft house built in 1989, in far west Houston (beyond Katy). In addition to the 3-ton A-S, there is also a 3.5 ton Trane XE1200 serving the northwest part of the house. Also surprisingly, the XE1200 has very few calls for cooling between noon and sundown, then it has to do some serious work overnight. I would not have figured this out looking at a Manual J report.

    Personally I am glad I got the 2-stage, but it is not a choice based on economics. You could make a very rational dollars-and-cents argument in favor of single speed, and I trust it would get the job done just fine, cycling on and off except on the hottest days. As far as I know the 2-stage models have as good a repair record as the 1-stage (but I made sure to get the long warranty just in case).

    Hope this helps -- Pstu

  3. #3
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Here in the swamp,hot humid Florida ,two stage is what we currnetly sell the most of.

    Customers love the reduced humidity,often truning the stat a couple of degrees higher ,as dryer indoor air feels cooler.

    Use the search function on this site to see what other homeowners think of their two stage systems.

  4. #4
    Join Date
    Jun 2008
    Location
    Houston, Tx
    Posts
    4
    Thank you both for the feedback.

    I guess my tough choice now is whether to scrap the one year old furnace. It isn't compatible with the new toys.

    Thanks!

  5. #5
    Join Date
    Sep 2005
    Location
    Bay Area, CA
    Posts
    843
    If your system is designed properly first stage is what you will be running at most and should keep up or run till it can not keep up with heat gain in the house in which time it switches to the second stage and then when that drops the temp it repeats. 2 stage units like to run alot and if your are use to on off cycles of your old equipment and judge energy efficency based on when its off and on then you will be disapointed in 2 stage cooling equipment.

    I've not had any failures on 16 seer scroll compressors yet, as far as 18seer trane a/s condensers we were told depending on the cause of failure for the compressor to change both as they were in the same loop and would fear one failure would cause the other to fail which would cause the other fail. Do to the fact they were in the same refrigeration loop. So you could see an increased cost at that point. But a properly installed and maintained hvac system you should not run into that type of failure for a long long time. And by properly installed that means having the proper ducting to equipment to outdoor unit.
    Global Warming or: None like it hot
    No pleasure, no rapture, no exquisite sin greater... than central air. -Dogma

  6. #6
    Join Date
    Jul 2005
    Posts
    435
    If the unit is sized correctly using manual J, the two stage will operate as designed. The first stage will run the majority of the time up until it can't keep up, and switch to stage 2, and then drop back to stage 1. It will never run on the second stage all the time, if and I say if it is sized correctly.
    Two stage units will offer more comfort since there is less cycling and the setpoint is maintained.

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