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Thermocouple not reading accurately.
I recently installed a type j thermocouple and watlow controller and am having issues with the accuracy of my temperature readings. I am using an analog guage as a reference to adjust my controller offset. The problem is that the temperature reading on the controller is not rising at nearly the same rate as the analog guage which is causing a significant difference in the read and actual temperatures. Could this be a grounding issue? I apologize as i am fairly inexperienced in this area.
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Comments
Could also be that the two are actually measuring different temperatures, since thermocouples (when wired properly) measure the temperature exactly at the junction and nowhere else.
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.
Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
This will introduce an error (a few degrees at best) but it's small AS LONG AS both sides of the splice are at the same temperature
Bob
Vaporstat with a 12oz cut-out and 4oz cut-in
3PSI gauge
I use K type wires to instrument new install equipment all the time. Sourced a few rolls from Omega, IIRC. I just twist the ends for the hot junction (longevity isn't an issue for me). It's cheaper to leave them in than to take 'em back out. Lately, I've stuck a few on refrigerant pipes, just jammed the junction into a dab of 15%, to see how long they'll last. My digital manifold uses K-type clamps for temp input, so I'll be able to validate them quickly.
With thermocouples (TC) have to use the same wire materials all the way back to the controler. They have junction blocks made of separate metals for splicing the 2 wires. If introduce a 3-rd metal then accuracy goes out the window. ( can't use a copper zip wire for extension)
One issue I ran into with a wire TC in portable use is the wires crossed and touched intermittently at the controller, so it was reading temp intermittently from the end of the TC wire and at the controller.
I didn't do it but on a TC at work I think they just soldered the 2 TC wires at the end with standard ~ 40/60 tin lead electronics solder.
Also there are at least 6 different commonly used pairs of TC metals. ( J, K ,T, E ........)
http://www.omega.com/techref/colorcodes.html