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Heat sensor for boiler pipes

What do you guys recommend as an inexpensive way to get a reading of the surface temperature of a boiler pipe?

I'm not looking to feed the temp to any controls, just for a visual readout of the surface temperature of the pipe it would be attached to.

I plan to use this to get an idea of the return temperature of branches to help in balancing them. Since they all share the same supply, they should ideally all have the approx the same return temperature, correct?

Is there a rule of thumb for determining the actual water temperature based on the surface temp of the pipe?


  • Brad White_34
    Brad White_34 Member Posts: 18
    I use an Azel dual thermometer



    This dual channel device comes with two thermistor probes (Tekmar type I think) which are grooved/curved for pipe curvature. I put them on with a dab of conductive paste and a pipe clamp under insulation and can read supply and return water. Alternately set them up to read anything at two points, outdoor air, supply water, return water...

    These run on batteries or 24V. I use mine on 24VAC power with battery back-up. Good product line but could be a tad less $ IMHO. Still, I bought three of these.

    As for accuracy, if the bond is good, there should be less than a degree difference compared to an immersion. One of my sensors is actually inserted in a thermowell with paste and reads about the same for my purposes as it did on the surface of the pipe. I do not know a formula for this deviation.
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