Chinese pid

M

MBurks

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Mar 21, 2016
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I bought a cheap PID to check accuracy of my new evenheat, now I don't trust the PID or the furnace.

According to the PID my furnace reads about 35 degrees hotter than what it actually is, but I don't think the PID is right either.

I connected the pic to the thermocouple in the evenheat, I'm not familiar with them at all, I can't switch it from Celsius to Fahrenheit.

Table salt should melt at 801 degrees Celsius, 1474 degrees Fahrenheit, so far no melted salt at 801 degrees Celsius in the PID and 1506 on the oven.

Any suggestions where I go from here?
 
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Sorry, not sure how to edit the new site, anything that doesn't fit should prolly be PID, damn autocorrect.
 
"The man with one watch knows what time it is, the man with two is never sure"

So what does the PID say when table salt does melt in the oven? How pure is your table salt? Is the thermocouple the same type as the PID is designed for?

There are a fair number of variables here, but your instincts are good. I would get some Tempilsticks in the range of temperatures you expect to be using your oven at, and put together a chart showing what the oven setting was when the Tempilstick mark melted. I'd be more inclined to trust the Evenheat than a cheap PID.
 
The location of the thermocouple is probably the reason you read different temperatures.


Pablo
 
When you use a second PID to check temperature you want to use a second TC, too. It is more likely that the TC is bad than the PID. Another reasons a PID doesn't read correct is wrong polarity on the TC wires and not using type K TC wire.
 
I thought about that last night, figured it might mess with resistance having them both hooked to the same TC.The only way I have to check with a second TC is by shutting the door on it, I tried that with the same results.

I appreciate any advice I'm unfamiliar with PID' s.
 
There are several different Chinese-made PID controllers. Some have better manuals than others. Some manuals are available online, others are not.

Since you are asking for help with a PID controller, it would seem to be quite a good idea to tell us which one it is, provide a link to the manual for it and tell us what settings you have put into it.
 
Check with a water/ice slurry which should be right at 32ºF as mentioned, then put at least last inch of TC in pan of distilled water (any water will work), being sure the tip of TC is at least an inch or more away from pan, and that "should" be very close to 212ºF as long as you're somewhere close to sea level. If you're 10,000 ft in mountain, apply proper correction factor.
While the boiling water doesn't give you temperature at 1,000ºF, it will at least give some idea the system is working.

Ken H>
 
http://m.ebay.com/itm/Digital-LCD-P...A-SSR-K-Thermocouple-/201734392383?nav=SEARCH

Thanks for the help.

The manual is terrible. I haven't figured out how to get it to display in Fahrenheit.

In ice water it's a consistent 6 degrees Celsius , which is 42 degrees fahrenheit so something isn't right.
The TC is the k type shown in the stickies.

Best I can tell it's set for a k type TC right now but I really haven't learned to navigate the controls.
 
There is something I'm missing. I go through all the steps in the manual to change to Fahrenheit and nothing happens. I found a better manual online and same results.
 
I've been studying around some different forums and best I can tell is buying the cheap eBay import PID's is hit and miss.

I've gone through all the steps to change the display, set for my TC and wire type, but making changes doesn't effect anything.

What I need now is a recommendation for a good PID in the cheap.
 
I've got several manuals for the REX-100, some of which are pretty good written in English as first language it seems. Since it seems email and PM's are no longer an option on this forum, if you'll send me an email to saingto at yahoo dot com I'll get you a couple of them.

The REX-100 seems to be a decent PID, but you do have to be sure you've got the correct model, which you can check from the part number.

Ken H>
 
I also found several manuals (and several different YouTube vids) for the Rex-100. Not sure which one you have, but I do believe all of them have a parameter to set the "bias" if your TC is reading a few degrees off. Most PID manuals I've read suggest calibrating it in some ice water, because it's a known value that should be right as 0C/32F.

USUALLY, you'll increase or decrease the bias parameter by the number of degrees you're off. I.E., if you're reading Celsius and ice water is showing 4 degrees, you'll set the bias to -4, which should make your knew reading right at 0C.

Found this video:

They cover calibration starting at about 4:45.
 
Best video ever!

That did the trick.

I still can't make it read Fahrenheit but it's at 0 in ice water.

You guys are great, thanks so much for the help.
 
I have one more question now that it's working.

For anyone that's used a PID to check a kiln, how did you go about sticking the TC in?

There is enough space in the door I can stick the TC in and close the door on it with the wires outside, other than that I will have to drill a hole.
 
Glad you've got it going. Be sure to check your model number, it might not have ºF ability. I have one PID that does only ºC

There's enough room in my oven I can just stick TC inside and close door on it. Only when it's getting over 1500ºF a good bit does the gap close tight enough to cause problems. I could adjust the latch to compensate at high temps, but have not.
 
That's the way my oven is too.

The PID IS advertised to read both F and C, but changing the value that is supposed to switch it does nothing.
 
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