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  1. #1
    Join Date
    Apr 2012
    Location
    Princeton NJ
    Posts
    125

    Algorithm for thermostat control of staging

    Hi, can I ask if anyone can explain how my trane 802 thermostat controls (zone panel set to thermostat control) the staging of my new trane 20i two stage air conditioner. I've read the manual, and done a brief internet search. I'm happy with the unit (and appreciate the forum convincing me not to upsize).


    1. Early morning the temp reading was 76, first stage cooling started, and ran in the 10-15 minutes. "inside temp" stayed at 76 the entire time. The stat senses less than a degree difference? Do I want it this sensitive?
    2. 79 in house, turned on AC. Second stage 2 hours (89 degrees outside), inside temp back to 76, then the stat dropped down to first stage for about 45 minutes (inside temp said 76 the whole time). It somehow calculated the rate of fall in temp, and it was 76.4, and the stat know first stage would be enough to 76.0?

    My final question---are any of the parameters user controllable (why would I want to change them is another question of course)?

    Thanks
    Steve

  2. #2
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,810
    You don't want to change them, first stage is more efficient and the longer run time from it running in first stage when it gets close to set point is dehumidifying your house so it feels more comfortable. That is how it's designed so it will dehumidify well and be super efficient

  3. #3
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,627
    Is it a trane zone or a honeywell zone
    We really need change now

  4. #4
    Join Date
    Apr 2012
    Location
    Princeton NJ
    Posts
    125
    Honeywell TZ4.

    A related question--i'm having the ductwork expanded for the bigger heat load zone. It will be able to handle both stages of cooling. But there is a smaller zone, that really can't handle second stage. What would be the easiest/best way to "trap" just one zone in first stage. The zone panel won't do it (% zone, or stat only). Can the thermostat in the small zone be reprogrammed?

    Thanks
    Steve

  5. #5
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,087
    Gotta know how it was set up. Best bet is % of zones calling so it doesn't go to high with insufficient duct capacity that will cause the system to shut down on safety.

  6. #6
    Join Date
    Apr 2012
    Location
    Princeton NJ
    Posts
    125
    Thanks. I tried that, the load of the big zone is more than the first stage, and the temp kept creeping up. In 90 degree weather it just won't work.

    Attach both first and second stage cooling wires on the stat to first stage? Replace the stat with an old school single stage stat?

    Steve.

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