Did you try wrapping some insulation around the sensor & pipe to see if 'ambient cooling' is affecting the reading? On Sun, Apr 25, 2021 at 2:14 PM Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote: I'm stumped. With my new coolant return plumbing (got rid of sharp 90 deg fitting) I relocated my temp sensors. Return from left rad used to sit on (black) 45 deg fitting and return from right rad on a 90 deg brass fitting. Now I have the right sensor under a silicone hose contacting the 3/4" alum tubing out of the radiator. The left sensor contacting the 3/4" tubing going into the return (was planning on moving it to left rad output tubing). The right probe now reads significantly lower (60F) than a non-contact thermometer pointed at rad and also when pointed at silicone hose. All sensors read the same when cooled down overnight. I realize I could clamp the right probe to the silicone hose, but felt that the hose would act as an insulator. Probes are LM35 or equivalent ICs. I had tested them in boiling water and ice baths and they were accurate within 1 to 2 deg F. I feel I'm missing something. An alum tube is a good heat conductor, right? Does its color matter when sensor is directly touching it (with heat sink compound to ensure better contact)? I'd rather not go the route of inserting 3/4" copper tuning (with well for sensor) into the return hoses, but perhaps the only way to get accurate measurements? Finn --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://maillancaironline.net:81/lists/flyrotary/List.html
I'm stumped. With my new coolant return plumbing (got rid of sharp 90 deg fitting) I relocated my temp sensors. Return from left rad used to sit on (black) 45 deg fitting and return from right rad on a 90 deg brass fitting. Now I have the right sensor under a silicone hose contacting the 3/4" alum tubing out of the radiator. The left sensor contacting the 3/4" tubing going into the return (was planning on moving it to left rad output tubing). The right probe now reads significantly lower (60F) than a non-contact thermometer pointed at rad and also when pointed at silicone hose. All sensors read the same when cooled down overnight. I realize I could clamp the right probe to the silicone hose, but felt that the hose would act as an insulator. Probes are LM35 or equivalent ICs. I had tested them in boiling water and ice baths and they were accurate within 1 to 2 deg F. I feel I'm missing something. An alum tube is a good heat conductor, right? Does its color matter when sensor is directly touching it (with heat sink compound to ensure better contact)? I'd rather not go the route of inserting 3/4" copper tuning (with well for sensor) into the return hoses, but perhaps the only way to get accurate measurements? Finn --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://maillancaironline.net:81/lists/flyrotary/List.html
This email has been checked for viruses by Avast antivirus software. www.avast.com