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Smart Thermostat Unusual Behavior in Aux Heating

RandomNameRandomName United StatesMember
edited February 2015 in ecobee

I'm having some unusual issues with staging on my Ecobee Smart Thermostat and I was wondering if others have seen the same things.

I have a Ecobee Smart Thermostat (bought and installed just before E3 was announced, sigh) hooked up to a 2-stage geothermal heat pump with electric aux heat. System is configured with reverse-staging, stage 2 cutin is -2 F from setpoint, aux heat cutin is -5 F from setpoint. Electric aux heat is configured with a 5 minute minimum runtime, simultaneous compressor and aux heat are enabled, compressor minimum runtime is 10 minutes).

I've been experiencing two strange issues with the staging:

  1. The use of aux heat seems to push the system into conventional staging. Based on my staging strategy, falling below 5 degrees from setpoint should result in enabling aux heat until the 5 minute runtime is met and the temperature is <5 F from setpoint. At that point, the system should stage down to stage 2. However, instead of staging down, the thermostat keeps the unit at stage 2 with aux heat on until setpoint is met.

  2. Aux heat will sometimes engage with only compressor stage 1 on when returning to setpoint. This behavior appears to occur when the setpoint is changed and temperature is >5 degrees from setpoint. This is unexpected based on the staging described above.

Has anyone experienced similar issues? I really appreciate any help you can provide.

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Comments

  • dpwctdpwct us CTMember

    Yes similiar problem wit stat-01 and water furnace intellizone controller

  • dpwctdpwct us CTMember

    Any update on ecobee working with Waterfurnace Intellizone

  • kevinmcckevinmcc Member
    edited May 2016

    This is one topic that really gets me about the Ecobee firmware programming.

    Stage 1 -1 F.
    Stage 2 -2 F.
    AUX -5 F.

    You would think all of these are either from set points or the previous stage, but that is not how it works.

    Stage 1 would be -1 F from set point, but Stage 2 is -2 F from stage one. So what about AUX? Is it -5 F from Stage 2 or the set point? The answer is set point.

    So there are a couple problem that can occur. If the sum of Stage 1 and Stage 2 are higher than the AUX you will start AUX before Stage 2 can even start. The other is you can set Stage 1 to -0.5 F and you can not set AUX at half degree increments.

    The confusing offsets are one of my biggest complaints. They need to either be half degree increments offset from the set point or different offsets.

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