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  1. #1
    Join Date
    Oct 2007
    Location
    Daytona Beach, FL
    Posts
    168

    Honeywell T7350 Temperature jumps around

    If you're wondering, it's the same job...

    A Honeywell T7350 tstat with the remote TR21-H Temp/Humidity sensor... The original complaint was the temperature was jumping around by 3-5 degrees, and that the humidity wasn't working. Took a new sensor to the site, and found the old sensor had a very obvious burn mark by the 24V input connector. Swapped out the sensor, and the humidity now works, but the temperature is dancing around by 1-3 degrees.

    My thinking is whatever killed the humidity side of the sensor, might have went back up the temperature sensor signal wire, and screwed up the stat.

    Going to go out to the site this afternoon and swap sub-bases, but wanted to see if anyone had any insight as to what might be wrong?

    The customer said he put a regular temp sensor on the temp line, and it worked fine. We put a brand new temp/humid sensor on, and it doesn't????
    NeonHomer
    BAS/BMS Technician/Computer Technician

    The definition of cruel joke is when you start work in BAS, and you run into your old T&B employer on the job.

  2. #2
    Join Date
    Oct 2007
    Location
    Daytona Beach, FL
    Posts
    168
    Swapped sub-bases... Temp still jumps around.

    Only thing I can think of now is that maybe the wire is bad, or it is picking up noise,.,..,.,
    NeonHomer
    BAS/BMS Technician/Computer Technician

    The definition of cruel joke is when you start work in BAS, and you run into your old T&B employer on the job.

  3. #3
    Join Date
    Jan 2006
    Location
    Sydney Australia
    Posts
    67
    if you have devices sharing the same 24V power, try making sure they are all wired to the same terminals and not crossed.

    read the install manual for device and follow it.

    hope this might help, its all i got

  4. #4
    This may be unrelated, but the T7350 head and subbase are a matched set. We have seen various issues arise when an old subbase is attached to a new head and vice versa.

  5. #5
    Join Date
    Mar 2003
    Location
    NY
    Posts
    2,144
    Sounds like noise to me. Have seen this before. Re-wired with shielded wire and routed away from several romex runs to solve the problem.
    "Controls is a lifestyle not a job" -klrogers

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