Fool temperature probes ??

[Flytox]

Personal annecdote: recently I tried to take "precise" measurements at 1/10 ° C with "pro" gear (differential electronic thermometer on K probes) ...

Well it's almost IMPOSSIBLE to have 2 times the same measurement within a few seconds (style you do an ON / OFF / ON and measurements = different) !! Well the errors were around 0.5 ° C but when you buy gear at 1/10 to € 100 you expect to have more precision than 1/2 ° C ...

When you are looking in 1/10 °, if you want less drifts, you have to give the electronics a little time for the heating to stabilize. The first readings are almost always wrong, "all" digital device or not and the manual rarely tells you about it. This can be seen when you measure the same thing with 2 identical devices and you switch off only one and plug it back in. It can take anywhere from 30 seconds to 2 minutes for them to agree.

I was measuring the T ° of copper pipes connected to a circulator: on the k probes (not jacketed) there is electrical disturbance because the measurements were different when the circulator started! This might explain that ?

When you search in the 1/10 of a degree, everything is a "pretext" to introduce measurement errors.
If you hold the probe in your hand for example.

[Christophe]

Damn, I was totally unaware of this story of "preheating" measuring equipment !!

Okay now I know!

For the "hand" which holds the probe (= external disturbances), uh all the same you underestimate me there! I had made a "clean" assembly: K probe stoached to the duct + pipe insulation from above.

[boubka]

hello chaboum
you should give us more information about your probes.
which type: pt 100; pt 1000; ctn; thermocouple etc
number of wires: 2,3 or 4
cable length and quality: 2 wire, 3, shielded, resistance, etc.

you have to check that your cable does not follow a power cable which little creates induced currents.
if your cable is screened verif that it is well grounded. and especially on one side.
you must also have good non-resistant connections

for freezing it is a constant deviation therefore calibration (to be corrected with resistance) unless it is done expressly for food safety of more

[Chaboum]

at boubka

thank you ! I would like to give you more info on my probes, but ... what type ?? pt100 pt1000 ???? how do you know? these are T ° measurement probes delivered as standard with my system. I have just reread the documentation for my solar water heater: it is simply said "T ° sensor" or sometimes "probe", but nothing more
cables ?? 2, 3 sons ?? armored (I don't think so but I don't know anything) resistance ??? FYI, my solar water heater system is a ROTEX Sanicube. What could I find for info? and especially where ????

For my boiler: ditto: it's an Okofen pellematic.

Otherwise, yes, I have probe cables that follow electrical power cables from: - my water heater and - my boiler. Question asked to the technicians: they always laid the cables like that (usually linked together, along a copper pipe) and it always worked. Possible interference with this installation system ??? how to know if it comes from there ?? check it ?? (because they will tell me that it has always worked)

thank you for your advice again. but it is true that I can not tell you much more, I would like !!!! pt100 ??? pt1000 ?? ctn ??? but how do you know all that ??

please