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Thread: HCF82 or HR92 Sensor bead type and location on PCB

  1. #1
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    Default HCF82 or HR92 Sensor bead type and location on PCB

    Hello

    Does anybody know what type of sensor bead the HCF82 uses? I'm looking to see if I can modify one to use a remote floor sensor... 10K would be convenient but I know Honeywell have a tenancy to use 20K sensors. Thinking about ordering one up to have a play with but was hoping someone might know to help before I did that.
    A HR92 would be even better (I have 2 spare) but I can't even find the sensor bead on that surface mount PCB... So if anyone knows where that one is and has a close up pic that could work as well.

    Thanks in advance.

    Alex

  2. #2
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    I'm not sure what you're planning to do with it as a "floor sensor" - do you mean a sensor to measure the water temperature of wet underfloor heating or element temperature of electric under floor heating?

    If so it's not suitable for that - at least not bound to an Evohome. An HCF82 like all the other remote sensors is designed for sensing the air temperature of the room - an underfloor heating system in addition to a room temperature sensor has an underfloor sensor to control the maximum temperature of the heating loop in the floor, (or elements if electric) and this is a separate feedback loop to the one controlling the air temperature in the room...

    The air temperature sensor controls the outer feedback loop which tries to regulate the room air temperature, which then requests heat from the underfloor heating which has an inner feedback loop that ensures the element in the floor doesn't go above a certain temperature.

  3. #3
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    Hello, thanks for the reply. Yes I know it's not suitable for that as it is and have a good understanding of control systems as a whole.
    I am also fairly handy with a soldering iron and could quite easily replace a soldered thermistor bead with a pair of wires off to my remote sensor in the floor, if I knew what type of bead was fitted as standard. I've just never seen the insides of a HCF82 so was hoping someone here had taken one apart which would save me having to order one and find out it's all surface mount micro components inside. I guess it may be a digital sensor but I think it's unlikely looking at how old that casing design looks. Ultimately I have an electric heat mat floor and just want to set it to 20șC without having to use a bdr91 to switch a second controller, which is how it is setup now.

  4. #4
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    Can't speak for the HCF82 but the HR92 doesn't use a discrete bead of any sort, it uses a temperature measurement chip with a built in sensor.

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