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K Type Thermocouple Thermometer Probe for Rad heat drop

Discussion in 'Plumbing and Central Heating' started by Possom, 28 Nov 2020.

  1. Possom

    Possom

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    If using a K-type thermocouple thermometer probe to measure radiator heat drop (pictured below), the probe is normally placed onto the copper pipe at each end.

    What should be done if plastic piping has been used, and a metal shroud placed over the plastic piping between each valve and the floor?

    Could the probe be simply placed directly onto metal sections of each valve, or directly onto the rad as close to the valve on each side as possible?

    Thanks.

    upload_2020-11-28_9-14-35.png
     
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  3. ericmark

    ericmark

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    I did have a differential thermometer and it did not really matter how the thermocouple was fixed to pipe, a bit of insulation tape was good enough as they were not moved for a period of time. However with a single thermocouple you need to measure while boiler is running as a set rate, so now use a Tommee Tippee Digital No Touch Forehead Thermometer which has the option to be used to measure baby milk temperature etc as well.

    Down to speed, no waiting for the thermal couple to heat up or cool down.

    However not convinced that the differential is any set number of °C drop, the TRV gives me current and target, TRV_report.jpg and I think the main thing is they should after a reasonable time be the same, if the lock shield if open too much, it will over shoot, and if closed to much will not reach target temperature, I have set using that philosophy and then tested with no touch thermometer and each radiator has given different results.

    So basic the differential thermometer is just a fast method of setting which will need tweaking after anyway, it allows the installer to get a near enough setting which he could not do by trial and error as simply does not have the time.

    Biggest problem is silly TRV heads with *123456 written on them, or I, II, III, IIII I have a TRV head in my draw, and when writing this I have tried adjusting so it just stops passing air when I blow through it, room at 19.7°C and it stays reasonably static at that, but the setting at which it stops passing air seems to vary between I and III, normally around I or less, it seems rather inaccurate, of course old that's why in my draw, but a new one marked *12345 not much better, again blowing it seems wide open at 3 and closed at 2, so 20°C is some where between 2 and 3, the ones in my mothers old house found around 3.4 = 20°C, which is rather useless when trying to set room temperature, you want the thermostat marked in °C this 61dmtMm13BL.jpg at least gives on a chance of setting correct, if you know set at 20°C then you can adjust the lock shield valve. As long as the wall thermostat does not turn the heating off while adjusting.
     
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  4. oldbuffer

    oldbuffer

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    1. Best put it on the valve nuts.
    2. Nothing wrong with putting it on the radiator close to the valves.
    3. If you put it on the pipes it will still work, but will take a little longer to register temperature changes.
     
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