Mash Tun Temp Display on Control Panel

[Dubchedford]

I apologize if this has been answered before. I'm planning a single tier 3 vessel E-HERMS system, based off of this PJ Diagram. The only thing I would like to add is a cheap display that shows the temp of the liquid leaving the mash tun. Are you guys just using another PID and using it only as a temp display, or you guys using another product. All of the digital temp displays i've found are twice the price of an average PID. Thanks in advance for the help.

 

[BigFloppy]

I'm using 3rd PID to display mash temp

 

[Beek]

Go here:
http://www.theelectricbrewery.com

Kal uses three PIDs. He doesn't have a complete schematic like P-J but there are a lot of step by step drawings of the wiring. I'm planning on doing a design very similar, just minus some things like the timer and the amp and volt meters. Pretty straight forward instructions. Kal is the man.

 

[BadNewsBrewery]

I use a 3rd PID - didn't even look for a temp display - it keeps everything looking uniform which is nice.

 

[Homercidal]

You can get cheap digital temp displays online.

 

[Dubchedford]

Homercidal, do you know where online to find them? All the displays I found capable of reading rtd sensors were well over 100 dollars.

 

[ClaudiusB]

Homercidal, do you know where online to find them? All the displays I found capable of reading rtd sensors were well over 100 dollars.

Ebay is full of low priced temp displays, under $20.00.

 

[Homercidal]

Homercidal, do you know where online to find them? All the displays I found capable of reading rtd sensors were well over 100 dollars.

I am not that familiar with the different types of sensors. Would an RTD sensor be required in this case?

 

[kal]

I use a 3rd PID - didn't even look for a temp display - it keeps everything looking uniform which is nice.

I did (Back in 2008) but couldn't find one I liked that would work with the same RTD temp probes I wanted to use. Like you, I also wanted some consistency with the look so 3 PIDs it was. It has a the added benefit of being a backup if ever one PID was to fail (since the MLT PID isn't 100% critical - it simply tells me when my mash has reach the target temp).

There are some available for ~$20 that use other sensor types but at the end of the day the extra $20-25 to go to a full PID was negligible in the cost of the brewing setup. A PID also lets you do alarming.

YMMV

Kal

 

[Dubchedford]

Kal, thats the same conclusion I'm starting to come to. Initially, My line of thinking was that purchasing a 3rd PID to simply use as a temp display was kind of a waste. So I started searching for cheap temp display that displayed in Fahrenheit and ran off of AC. All the meters I found were well over 100 bucks. I searched Ebay and displays I found either ran off of DC or displayed in celsius. So now it looks like the PID is actually the cheapest option, plus I get the extra features of a PID over a display, and a spare in case one fails.

 

[conpewter]

what about using a switch so that you can change what temperature is displayed on the PID?

I'm thinking that during the mash I don't care what temperature the boil kettle is at (it's empty) so put a switch that would switch the RTD input on the boil kettle PID

This switch looks great for that use. triple pole double throw, looks like low resistance. two for $7

http://www.ebay.com/itm/2pcs-TPDT-S...379?pt=Guitar_Accessories&hash=item258ebb3ca3

thoughts?

 

[LandoLincoln]

Kal, thats the same conclusion I'm starting to come to. Initially, My line of thinking was that purchasing a 3rd PID to simply use as a temp display was kind of a waste. So I started searching for cheap temp display that displayed in Fahrenheit and ran off of AC. All the meters I found were well over 100 bucks. I searched Ebay and displays I found either ran off of DC or displayed in celsius. So now it looks like the PID is actually the cheapest option, plus I get the extra features of a PID over a display, and a spare in case one fails.

I have two temp-only displays on my control panel - one to show MT temps and one to show chiller temps. They were around $18 shipped off of ebay. The seller was Procon-Products. The name of the item I bought from them was "Digital Temperature Meter for RTD PT100 Sensors (F/110)"

Ebay item #250560351944

It doesn't look like they sell that particular unit anymore, but they DO have something called "Universal Display Meter for Thermocouple (K,S,R,J,B) , RTD, Current and Voltage" which accepts AC current. Ebay item #251025747167

I think that this would work for you.

Not sure what the "current and voltage" thing means.

Be prepared to wait a month since they ship from China.

 

[kal]

what about using a switch so that you can change what temperature is displayed on the PID?

Biggest issue with that is that the PID has a temp offset in it that you set to account for inaccuracies (which all temp probes will have to some degree). So with with different probes, only 1 (or neither) will be accurate. Not sure if that matters to you.

The other issue is the control aspect: I'm not sure if you're wanting to control two different "systems" in automatic mode but you can't really do that since the P/I/D values in the PID are "tuned" for the specific components that make up the "system" (temp probe/PID/heating element). This is what auto-tuning does. It learns how the system behaves. If only one of the systems is run in automatic (and the other in manual) then this part doesn't matter.

Kal

 

[conpewter]

Biggest issue with that is that the PID has a temp offset in it that you set to account for inaccuracies (which all temp probes will have to some degree). So with with different probes, only 1 (or neither) will be accurate. Not sure if that matters to you.

The other issue is the control aspect: I'm not sure if you're wanting to control two different "systems" in automatic mode but you can't really do that since the P/I/D values in the PID are "tuned" for the specific components that make up the "system" (temp probe/PID/heating element). This is what auto-tuning does. It learns how the system behaves. If only one of the systems is run in automatic (and the other in manual) then this part doesn't matter.

Kal

Good points. I'm not sure how far off two PT100 probes would be, if it was more than a degree though then this wouldn't work well.

I wouldn't be controlling two systems with one PID, just controlling the boil (so would never need to tune... always manual mode) I know I could use some sort of PWM instead of the PID in manual mode, but I like the look of two identical PIDs

 

[NathPowe]

Similar question regarding PID's for temp display - let's say a guy wants to use a PID to monitor the temp of cooling wort (using an immersion chiller), measured with an RTD at the output valve on the boil kettle. Then let's say that switches have been install to manually turn on/off power to the elements (switches on the 120V line to each SSR - this would be a dual element 120V build). Is it bad for the PID and/or SSR to just be running with power to the elements switched off? With the elements off, I assume the PID would just continue to do it's thing, be it manual mode or PID mode. It would essentially just be a temp display, but does this creates additional/unnecessary wear & tear on the PID and/or SSR?

Not sure if any of that question made sense. It sort of did in my head.

Thanks and Cheers.

 

[Brumateur]

There is absolutely no additional tear or wear happening to PID if it' runs with no SSR/element connected.

 

[augiedoggy]

Ebay is full of low priced temp displays, under $20.00.

Yup.... but its also full of pids that have manual mode and every feature of the $60-80 auber pids like the ones I use which are under $20 below.

http://www.ebay.com/itm/231206228037?_trksid=p2059210.m2749.l2649&ssPageName=STRK:MEBIDX:IT

this way if you eventually want to upgrade to a rims setup or one of your pids malfunctions your ahead of the game...

Auber is becoming the the "Monstercable" of this hobby IMHO ... Those in the home theater hobby should know what I mean... Their products work well and their customer service is good but you pay a premium for it.