Waterfurnace aux heat problem

Discussion in 'General Discussions' started by dpwct, Oct 30, 2013.

  1. dpwct

    dpwct New Member

    We have a waterfurnace geothermal system installed the aux heat seems to be going on even when thermostat is set to just 1 degree above current room temp - In other words aux electric heat is going on instantly (when only compressor should be on) further more the thermostat display shows stage 2 not Aux.

    Checked all settings and wiring and everything looks ok. Any thoughts on cause - could it be faulty thermostat.

    Specs - circa 2010
    - WaterFurnace Envision model NSZ022 split unit
    - WaterFurnace air handling unit model # NHA022A0501R 5kw heat strip
    - TP32U03 Thermostat
  2. geoxne

    geoxne Active Member Forum Leader

    The instructions for that thermostat is here-

    Operation of the system is determined by installer settings. If it is setup to defaults and recommended settings for your equipment, Stg 2 indication could mean only a higher blower speed (with single stage compressor).

    If you are absolutely certain aux electric heat is coming on prematurely check for the following settings-
    -Differential- degree separation between stages
    -Smart Heat Staging- aux heat time delay none to 60 min.

    Also check
    -Display Options-Aux Heat Display-On or Off

    Warning please read page 4 NOTE under Installers Setting about end users ... equipment stop working...void the warranty!
  3. dpwct

    dpwct New Member

    Yes the technician checked and verified with an amp meter that electric heat was on prematurely (when stage 2 displayed)
    What do you suggest for settings for

    -Differential- degree separation between stages
    -Smart Heat Staging- aux heat time delay none to 60 min.

    As for blower speed I believe there is only 1 blower speed on this model - do you know if that is correct
  4. geoxne

    geoxne Active Member Forum Leader

    I suspect in your case Y2 is jumped out to W or W2 some where between the tstat , airhandler and compressor control board.

    The quickest remedy without rwould be to change STG2 differential to retard STG2 call-
    -Installer Settings- follow instruction guide
    -Differential-Enter-1ST Stage-0.5-Enter-2ND Stage-1.5-Enter-Previous-Home

    A Stage2 differential of 1.5 as above will not allow a Stage2 call until room temp drops 2 degrees (Stg1diff+Stg2diff) below set point (adjust to your balance between comfort and electric heat cost).

    Your NHA022 has a ECM blower and is configurable for adjust speeds for G, Y1,Y2 and Aux.

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