Many RTD's only one controller

Equipment: Just starting getting equipment together for e-HERMS. I have my old control panel which has 1 PID. I now have multiple RTD sensors in the system.

Problem: How to check temperatures with-out switching or swapping out control panel PID. It looks like a bunch of guys used switches in there setup. I basically just want to use some of the RTD's as a temp check when they are not in the control loop to understand my system better.

Question: Is there a cheap way to use an RTD just as a thermometer?

I know that Dwyer sells panel mount temp indicators that are NOT controllers. The question is whether any of them can take an RTD input. I believe there is some question as to whether adding a switch into the loop will cause accuracy issues. The other problem is that an RTD/display pair needs to be calibrated and switching to a different probe can be off.

I see what you're trying to do, it would be kind of cool to have a digital display with a rotary knob to cycle between all probes in the system. However, something like this is probably much easier with a BCS.

I was just thinking about the same thing. It would be nice to have a digital display just showing the temps.

Auber Ins was very fast with getting back to me. I had just asked him the same question as the OP.

If in AUTO and you switch RTD inputs, the PID will be totally confused. If you are in manual mode switching is no problem (as long as you are not concerned about the calibration of each RTD) NOTE: if you switch make sure you have a good switch


So it looks like a cheap PID is the best way to go if you have many RTD's and switch between them (just make note of differences in calibration between them - The offset is fairly consent I gather so it will just be +/- a constant that I will post next to the switch). My control panel is full, So I think I will order the cheapest Auber PID (SYL-1512A), some panel mount disconnects for the sensor wire, a switch or two, and get a box from the hardware store to house it. Not worried about using it to run anything so no SSR or heatsink required.

BOBBY M - just looked up DWYER - looks like Series 40T/40M Digital Temperature Switch would be the model, but it is $50ish compared to $30ish from Auber.

I had really good luck with this unit
http://www.ebay.com/itm/250560351944 it did take a long time to get from china though.
I have a pid, but can monitor the other 2 rtd's with the meter above. I just have the sensors hooked up to a on off on switch from auber, he sold me extra contact blocks so I could switch all 3 wires of the sensor.

JRems said:

I had really good luck with this unit
http://www.ebay.com/itm/250560351944 it did take a long time to get from china though.
I have a pid, but can monitor the other 2 rtd's with the meter above. I just have the sensors hooked up to a on off on switch from auber, he sold me extra contact blocks so I could switch all 3 wires of the sensor.

Click to expand...

GOOD FIND! Did not even think of just looking for TEMP DISPLAY. That is definitely a cheap option. Not a huge fan of EBAY even though it would probably save me $. Tried to find the linked temp displays anywhere in the US and it is impossible (with my limited skills). Still leading towards supporting AUBER INS.

What do you mean by contact blocks? I was just gonna get the extra panel mount disconnects for the RTD's and run that through a switch to flip flop.

JRems said:

I had really good luck with this unit
http://www.ebay.com/itm/250560351944 it did take a long time to get from china though.
I have a pid, but can monitor the other 2 rtd's with the meter above. I just have the sensors hooked up to a on off on switch from auber, he sold me extra contact blocks so I could switch all 3 wires of the sensor.

Click to expand...

I have 4 of these and ordered 5 more. They are cheap and easy. My Favorite two words. I am anal on wanting to know the variation of temperature distribution in my process control. Obviously more than making beer. You wouldn't need that many for beer. You search ebay and you can find probe's pretty cheap if your willing to wait for them to shop from china. I think the probes were like $7 the display was $15 so for $22 I have a readout anywhere anyway I want. I'm actually mounting 4 into one box that will be portable to allow me to test whatever new project I'm working on to make sure there is no temperature stratification.

JRems said:

I had really good luck with this unit
http://www.ebay.com/itm/250560351944 it did take a long time to get from china though.
I have a pid, but can monitor the other 2 rtd's with the meter above. I just have the sensors hooked up to a on off on switch from auber, he sold me extra contact blocks so I could switch all 3 wires of the sensor.

Click to expand...

wadefisher said:

I have 4 of these and ordered 5 more. They are cheap and easy. My Favorite two words. I am anal on wanting to know the variation of temperature distribution in my process control. Obviously more than making beer. You wouldn't need that many for beer. You search ebay and you can find probe's pretty cheap if your willing to wait for them to shop from china. I think the probes were like $7 the display was $15 so for $22 I have a readout anywhere anyway I want. I'm actually mounting 4 into one box that will be portable to allow me to test whatever new project I'm working on to make sure there is no temperature stratification.

Click to expand...

Have you had these for a while? Just wondering about their durability. This would be a nice cheaper option than going with another Auber PID just to monitor mash temps.

I Only used it for 2 brews so far and it's been working fine. I don't think it's quite as waterproof as the auber pid, but I don't plan on running a hose on it. It seems pretty well made.

Anyone know if you can hook one of the cheap ebay displays to an alarm or can you really just display the temperature?

It's just a temp display, there is no way to turn an alarm on directly from the display.

JRems said:

It's just a temp display, there is no way to turn an alarm on directly from the display.

Click to expand...

I'm thinking this is the perfect solution for the mash tun. I didn't need any control, just want a display. I went ahead and ordered one and will see how it works out.

I am looking to get a couple of these.
Are they accurate? I don't suppose you can do any kind of temperature calibration can you?

They seem to be very accurate. I don't see a way to calibrate, but for me wasn't necessary it was spot on. There was no instructions or manual with it.
Or if you really want a calibratable model you can get one here for close to $200
http://www.alliedelec.com/lp/120327...&utm_medium=email&utm_campaign=120327_product

I was looking for something along these lines too, for the boil kettle and the mash tun. You can do that and a PWM for less than the cost of a PID.