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Ecobee3 Humidity

tcrow1988tcrow1988 IllinoisMember

So I have an Ecobee3 thermostat, and I recently installed an Aprilaire 600 humidifier. After much experimentation I think I have the frost control set up correctly to no longer frost up my windows, but I've been doing some more research into my run logs and noticed something odd. Looking at the humidity graphs, whenever my furnace (gas, single stage) kicks on, the humidity spikes an then drops back down to normal immediately after the furnace and blower shuts off. This occurs whether or not the humidifier has been scheduled to run or not.What could be causing this? Shouldn't the warmed air from the furnace cause the humidity to decrease due to greater capacity to hold on to moisture? It would seem that these spikes are causing my humidifier to turn off prematurely and not reach the "true" humidity setting. Any input would be appreciated.


  • SneakXSneakX MontrealMember

    Could you look at the wiring of your humidifier controls ? Maybe it is interlocked with your furnace.

  • LarrylLixLarrylLix Northern Southwestern OntarioMember
    edited January 16

    I monitor my humidity separately from my ecobee3 and ecobee4 using CAO Tags.
    The stats humidity calibration wanders with usage, warming and cooling the stat sensor down with the electronics heat inside.

    Humidity is erratic on the stats and in the house with my external monitoring also. A door gets opened and the humidity in an air pocket will drop by 5% in minutes.

    You have to worry about the long term average of the humidity in the walls and furniture more than the short term, which you will not be able to measure accurately or control accurately anyway.

    Your stat or furnace may have a flushing feature where your fan will run past the heat cycle. This could cause the temporary humidity jump also.

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