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Original question:

HDC2080: Temperature range and Heater function

HDC2080: About the control method of the heater

takaaki inoue
Prodigy 70 points
Part Number: HDC2080

Please tell me at what timing the heater should be turned on and off in order to measure the temperature and humidity accurately with the sensor.
If there is a control specification of the heater, I want to see the specification.

The question is
・ Is it better to turn on the heater when the dew point temperature is reached? Please tell me when to turn on the heater.
• How much does the heater turn on will release condensation on the internal polymer?
・ Is there any way to know that condensation on the internal polymer has been released?
・ If the heater is turned on, the sensor generates heat by itself, so it may not be possible to measure an accurate temperature. Is it wrong?
Please tell me how to measure the exact temperature without the influence of the heater.
・ I want to know how to measure the humidity after turning on the heater.
Can you not measure the humidity correctly without releasing the condensation of the internal polymer?

  • 0
    TI__Guru* 91206 points

    Dear Inoue-san, 

    These are great questions, and the exact answers depend on the feature of both the HDC device and the capabilities of your system or end equipment. 

    I will do my best here to try to guide you here - and it is a topic that I think deserves more attention in our documentation, which is on me now - so look for future updates to cover this topic. 

    1. If the scenario you are describing is an environmental control system - the system must use the measurements to then calculate if dew point is being approached and make adjustments to temp or humidity of the environment to prevent the condensation from occurring in the first place. If the control system takes no action and the condensation occurs - the RH measurement would most likely be then 100% or very close to it - so then I am not sure that the heater alone would be able to heat up and remove condensation at a greater rate than if was being formed, that would be very specific to the situation or the instance, I think. 

    The heater tops out at about 100C and the impact of it being on make the returned humidity level drop drastically. Here you can see a graph of HDC EVM operating at room temp/humidity and me turning the heater on, letting it rise up to 100C and then turning it off, to show the result of it then coming down in temp and humidity levels going back up.

    The difficult part about telling you specifics is your test or actual conditions might vary greatly from anything I could propose and if you did not have a control system, then all you could do was use the HDC device to do then is make an alert that condensation did occur - but as long as condensation was persistent, I am not sure if trying to use the heater at that point makes sense. 

    I think if you have more specifics about your entire system, that would help to continue the conversation here - which i think is a good idea. 

     

  • 0 in reply to Josh Wyatt
    Prodigy 70 points

    Dear Josh Wyatt

    Thank you for your quick response.

    The device I design is a device installed in a home.
    The place where the device is installed is supposed to be the living room of the house, dining etc.
    Measure the temperature and humidity of the room where the device is installed.

    The temperature and humidity measured by the device are
    It is used to do things such as urging the householder where the equipment is installed to be air conditioned.

    I would like to use the HDC2080 to accurately measure the temperature and humidity where my device was installed. In order to make full use of the HDC2080, we believe that it is also necessary to control the heater.

    I'm sorry if it is rude language because English is not your native language and it is poor.
    Please continue your advice.

  • 0 in reply to takaaki inoue
    TI__Guru* 91206 points

    Dear Inoue-san, 

    I think you have communicated effectively for me to understand. You describe an operating environment will be in a residential environment, which is climate controlled. This means most likely that the typical installation will see >30%RH to <60%RH and within ~16°C to ~28°C.  I don't see any reason to use the heater on the device in this application. It would be primarily for eliminating any condensation or VoC exposure. As most indoor applications do not have a condition where the dew point is met, where the device is installed. The exception to this might be if the sensor was placed near/around a window in wintertime and dew point was reached in that specific area of the building.