Temp sensors under reading

Discussion in 'C-Bus Wired Hardware' started by Rbw, Apr 23, 2018.

  1. Rbw

    Rbw

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    Hi all... so much great info here, so hoping someone can help with my problem...

    I’ve just inherited a house with a a CBUS network on which are several 5031TS units. Each of these are consistently under reporting the temperature by ~5 degrees Celsius. So a unit will report 18 degrees in CBUS Toolkit when the real temp is 23, as measured by multiple standalone digital thermometers. The delta seems pretty much the same across all units. All units have a sane placement.

    Has any one experienced this issue before? I can find nothing about any calibration options for these units, but if I’m missing something I’d love to know!

    Also, could anyone explain to me how the “margin” setting works for these units or point me to where I can read more about these kinds of details?

    Thanks I’m advance,

    RB.
     
    Rbw, Apr 23, 2018
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  2. Rbw

    Ashley

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    The 5031TS is a very early unit and has limited functionality compared to current devices. They have no calibration option. I assume as the temperature set point was fixed via toolkit (i.e. not user adjustable) you would just take any error into account when programming the temperature set point. You don't say how the units are being used. If they are just triggering a fixed load at a predefined temperature you could just reset the set point. If you have a logic device reading the temperatures and controlling loads you could just take the error into account in the logic.

    The margin controls the dead band. For example if you are in heating mode with a set point of 25 degrees and margin of 2 degrees, the heating will come on when the temperature drops to 23 degrees and go off when it reaches 25 degrees.

    As far as the error itself goes, 5 degrees seems a lot. A couple of degrees is common, and in my experience they tend to read high (I assume due to internal heating). Given their age however, anything is possible.

    The current units provide a calibration offset plus much greater functionality.
     
    Ashley, Apr 24, 2018
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  3. Rbw

    Rbw

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    Thanks for all the info Ashley, it’s a great help. I know understand the margin setting

    What I found strange was that all units were consistent in their under reporting and from the set points that were configured when I first took on the system, it looks as if they were initially reading more or less accurately.

    I have of course adjusted the set points to take into account this error. What’s a bit disappointing is that it means all the temperature displays that were configured in homegate don’t make much sense. Oh well, I don’t think I can be bothered to replace the units at £180 each!
     
    Rbw, Apr 24, 2018
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  4. Rbw

    crispyoz

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    I'm not sure of this is relevant to your issue, but I use 3 different sensors to read the temperature, each set at different heights. The temperature varies by a few degrees between ground level and ceiling level. I take an average of the 3 sensors to arrive at a usable value to control my climate control system.
     
    crispyoz, May 3, 2018
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