Where can I buy an Aprilaire outdoor temperature sensor?

Consumer question:

My HVAC contractor installed the Model 600 humidifier in manual mode (without the outdoor temperature sensor). Where can I buy the sensor & wire? What is the model # of the sensor? Are there installation instructions for it and also humidistat controller wiring instructions?

Aprilaires’ response:

Thank you for contacting us regarding the outdoor sensor for your model 600 humidifier. You can contact your installing contractor regarding the installation of the sensor or you can purchase the outdoor sensor from our estore by following the link below:


Also, please view the attached humidistat control installation manuals. There are different wiring diagrams depending on which control you have so be sure you are looking at the correct diagram for your control.

We always recommend any installation be done by a licensed HVAC contractor. When our products are installed by a licensed HVAC contractor, they come with a 5 year warranty beginning on the date of installation.

If you have any further questions regarding this or any of our products, please feel free to contact our customer service department at your earliest convenience.

4 thoughts on “Where can I buy an Aprilaire outdoor temperature sensor?

  1. Gary L. Housman

    My so called authorized installer also was going to install my unit without the outside temp. monitor.
    If the outside thermostat works as you say, I find it hard to believe you even make it a option.
    I consider the monitoring of outside temp. as important as the unit itself.
    Is there something I am missing?

    Sorry but I have to say that I am really tired of getting half for my money!
    Thanks for your time and reply.

    1. aprilaireadmin

      Thank you for contacting us with your question about the outdoor temperature sensor. Our outdoor sensor is used with our thermostats and our digital humidifier control. We are answering your question with the assumption that you are referring to our automatic digital control for the Aprilaire humidifier; yes, it is an option to not install it. The control is set-up without the sensor in “manual mode” where the need for a constant humidity level is mandatory despite the outdoor temperature and potential condensation on the windows. Typically this application would involve an antique piano or other humidity-sensitive instrument or collection requiring a continuous relative humidity.

      For those of us that don’t have this circumstance and experience warmer winter temperatures during the day with much cooler temperatures at night as we do in the Midwest, you are correct that the outdoor temperature sensor is very important for accurate humidity levels in your home. As you are aware, the outdoor temperature sensor allows the digital humidistat to automatically adjust to the proper humidity level for the current conditions in your home and the outdoor temperature. You may wish to inquire with your installing contractor if there is a physical barrier preventing them from installing the sensor? If that is the case, the sensor can also be installed in your fresh air intake pipe if you have one in your home.

      We welcome you or your contractor to contact us with any additional questions. We appreciate you choosing Aprilaire to complete your indoor air comfort. Thanks again for contacting us.

  2. James Brennan

    My aprilaire humidifier mod 600 does not work .Checked the solinod an it ok. Humidifier does not work in the test mode.When turned to test the green on light just flashes. Please assist me with some advise.It does have a outside sensor . Should I try bypassing it and if so do I just jump it with a wire.

    Thank you

    1. aprilaireadmin

      Hello Jim,

      Thank you for contacting us regarding your humidifier. What model control do you have for your humidifier? When you are testing the unit is the furnace on?

      Please let me know and I can help more!


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