K type thermal couple and auber syl-2352

I went through and calibrated all my thermometers today, thinking that i was about to start making pislners and mistakes in temperature are harder to hide in this style. I have an electric hot liquor tank with a k type thermalcouple hooked up to an auber syl 2352. so to check/calibrate this thermometer i have 2 others that were already calibrated and used to measure the temperature in the hot liquor tank. the two calibrated thermometers were consistenly withing 2 degrees of each other. the k type hooked up to the 2352 was all over, and the offset (Pb variable on the controller) was different depending on the temperature i was measuring. it is not a consistent offset through the teperature range i a measuring. Is this typical for k type thermalcouples? or did i somehow mess mine up?

I am looking at using this controller to build a HLT also. Which length of probe are you using? I was thinking of using the 4" but am worried it will be in the way and get damaged.

Do you need a way to circulate the water to evenly distribute heat throughout the volume of water?

Did you cut the probe cable and add some sort of plug?

With my limited experience with thermocouples, I've found that one of the wires (I forget the alloy) can get brittle & break rather easily with flexing. This intermittent open will cause very erratic readings so it's something to double check. Also check whichever options need to be selected in the controller setup & polarity.

If the PID itself is getting hot (or cold), or if hot air is blowing over the back of it, your readings might get skewed. There is a small diode just inside the vents (you might be able to see it) that is the cold junction. It needs to be at the same temperature as the thermocouple connector.

Bf I am running the same controller and doing a setup similar to Kal's. I am running K - type thermocouples as well and have had similar troubles. I might switch over to a single rtd to test the differences out.

Cutting thermocouple wires up (possibly to add connectors or lengthen the wires) will introduce error that can vary throughout the temperature range. Rtds are another thing altogether and the wire can be cut up almost as you please.

Bottom line: dont mess with tc wires

ok that makes sense somewhat. I bought a Special through bulkhead plug for my thermal couple. I cut the wre added the plug and female end. Also i am using the 4 in probe. i had a 2 inch but it was to short, my temp proble is mounted through a t fitting and into the HLT. I recently added a pump to my system and it mixes the hlt thoughroghly. My control mox is sealled, looks like i need a fan or something.

the small pot is the HLT, you can kinda see the thermalcouple where the sight gauge is and on my control box is my thermal couple plug

hrafnkell said:

Cutting thermocouple wires up (possibly to add connectors or lengthen the wires) will introduce error that can vary throughout the temperature range. Rtds are another thing altogether and the wire can be cut up almost as you please.

Bottom line: dont mess with tc wires

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I am using a 2" K type braided with the 2352. I cut the connectors off and put a male/female panel plug on it. From the PID to the connector is copper stranded 14 gauge i think. I have consistent and accurate temp measurements in my RIMS system throughout the temp range. 60-215

i am starting to think maybe it is my control box or something. my control box isn't cooled and it is sealed, hmm maybe its time for a rebuild. Do you think it could be related the box being sealed and heating up inside?

oh and the wire for the control panel mount to the pid is the same wire as the sensor wire, i just snipped 6-8 inches off it and reused it.

bf514921 said:

i am starting to think maybe it is my control box or something. my control box isn't cooled and it is sealed, hmm maybe its time for a rebuild. Do you think it could be related the box being sealed and heating up inside?

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If the SSR is in there it is probably getting hot. Get a CPU fan and a heatsink. Got a Pic of the inside?

bf514921 said:

i am starting to think maybe it is my control box or something. my control box isn't cooled and it is sealed, hmm maybe its time for a rebuild. Do you think it could be related the box being sealed and heating up inside?

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Please refer to my post above. I have the same PID, I use thermocouples, and I rebuilt my box for this exact reason.

passed pawn, i just went back and re-read your post, i have a heat sink with the ssr, but its inside the box, so i think i will be rebuilding the box with a fan and all. that is a good thing to know. Also as a side note, i really only figured this out because i calibrated ALL the thermometers i use. oh well i have been wanting to rebuild anyway. if i remeber i will try to resuresct this thread with an update

pic of the inside, 2 ssrs with no way for air moment, dfinately could cause a problem. I think my powerblock might be a little overkill too.


the yellow plug is the thermal couple plug for the ktype

i appreciate the help, i didn't read my manual thouroughly enough for my pid, i might have known about the ambient thing with the cold sensor on the PID

I have a sealed box as well. I am wondering that if I was to move the diode to the outside of the case would be a better way to provide the required cold junction compensation?

ohararp said:

I have a sealed box as well. I am wondering that if I was to move the diode to the outside of the case would be a better way to provide the required cold junction compensation?

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Ideally, the cold junction (i.e., diode) and the thermocouple connector are at the same location and temperature. If the inside of your box is getting hot, and the thermocouples are connected on the outside of the panel, you'll have problems. The reason the cold junction inside the PID is hanging near the back of the package is to get it as close to the screw terminals as possible.

My first box was very similar to yours there (I used the same panel-mount thermocouple connector, but a dual-type). I had horrible problems with accuracy once the SSR started heating up the box. My new box has a large heat sink mounted outside the box. Problem solved.

thanks again passedpawn, looks like i have a new project for the evening, good thing i got my basement cleaned up today so i can mess it all up again

bf514921 said:

thanks again passedpawn, looks like i have a new project for the evening, good thing i got my basement cleaned up today so i can mess it all up again

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You could just cut a hole behind each SSR for the heat sink to protrude out of the panel.

Yep definatly thought about that, but i have been wanting to redo my controller again anyway, make it nicer cleaner, plus this is a good think to know and understand about the the pid and the ambient teperature sensor on the back of the pid

Stevo2569 said:

You could just cut a hole behind each SSR for the heat sink to protrude out of the panel.

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Did mine like this. The SSRs are not mounted to the case, they are mounted to the heatsink which is mounted to the outside of my box. I then cut a hole in my box big enough to run the wires through. It was pretty easy. I had to drill a couple of holes in the heat sink to add some mounting hardware.

yep, mounted the heatsink outside, now all my thermometers are within +- 1 degree of each other, that is ALOT better