PID question

[powermd]

I'm trying to build a temperature stabilization system for my primary and secondary ferments based on a PID controller that activates a water pump that circulates ice water through a bath containing the fermentation vessel.

I have a JLD612 hooked up to a SSR, temp probe, and pump. The PID is set to cooling, so it's supposed to activate the pump when the temp rises over the set temperature. The pumped water then cools the fermentation tank to the set temp. I know my basic setup works because the previous application was heating a water bath for sous vide, and it worked fine and maintained the set temp without issue.

The issue I'm having now is that once the temp drops below the set temp, the pump does not shut off. It runs slower, and in intermittent pulses, but it keeps circulating. I tried adjusting the parameter for overshoot to the max, but that does nothing. What I'd like is a simple binary on/off depending on where the temp is in relation to the set temp. Any help would be appreciated.

 

[Walker]

What PID do you have? You need to change that thing so that it operates like a basic thermostat and not an intelligent PID.

You might just need to change the "I" and "D" parameters of the PID to "0". That should basically kill it's smarts.

 

[atreid]

What PID do you have? You need to change that thing so that it operates like a basic thermostat and not an intelligent PID.

You might just need to change the "I" and "D" parameters of the PID to "0". That should basically kill it's smarts.

Actually, on the cheap PID I got from EBay, setting the P parameter to zero will turn the control into full ON/OFF control.

So you could try that...

 

[Walker]

Yup. It will be different depending on the PID design. The PID I have, I would have to actually use one of the alarm functions to do this and not even use the main output of the PID at all.

 

[atreid]

Yup. It will be different depending on the PID design. The PID I have, I would have to actually use one of the alarm functions to do this and not even use the main output of the PID at all.

Can the alarm function be used to trigger the SSR? Does it provide a constant voltage? That is what you do? (I know it sure depends on the PID)

I'm using my SSR connection for the Cooling but if I can configure the alarm to trigger when temps go down a specific temperature, I could link the alarm port to another SSR to provide power to an old heating blanket I have.

 

[Walker]

The alarm relays are just basically switches. They don't drive anything by themselves. You have to hook something up to 1 side of the relay and when the alarm triggers it will pass that something through to the other side of the relay.

Depending on your specific PID, you might not even need to use an SSR. The relay switch built into the P ID might be able to handle driving your pump directly.

So you would just hook 120 volts to one side of the relay and take the wire from the other side of the relay to your pump. hook your neutral straight to the pump.

Then you just set the alarm parameters to trigger the relay at whatever temp you are concerned about and the alarm relay will kick on your pump.

If the alarm relay cannot handle the load of the pump by itself then you could run a DC power source through the relay to drive the SSR to drive the pump.

If that did not make sense, I can probably draw you a picture.

 

[Walker]

Let me know which PID and pump you have. I can give a better answer that way.

 

[powermd]

Let me know which PID and pump you have. I can give a better answer that way.

I have a JLD612 PID, and Rio 600 10w pump.

I tried changing the P value as low as possible, which was 0.1. This seems to have fixed my problem, as the pump will completely shut off after a while below the set temp. It's not immediate though. If there are any other changes to my settings and I would help make this transition more immediate, I would be interested in doing that.

 

[Walker]

That's the exact same PID I have. . You will need to make use of the alarm relay.

I'm out and about right now, but I can help more later.

 

[Walker]

You probably have the PID programmed with the "outY" parameter set to "2". This is the mode where the main control output is set to drive an SSR. In this mode, the JLD612 has two alarm relays available to use.

J1 is a double throw relay for alarm1 functionality.
Pins 4 & 5 form a normally closed path (switch is ON when alarm1 is NOT active and OFF when alarm1 IS active).
Pins 5 & 6 for a normally opened path (switch is OFF when alarm1 is NOT active and ON when alarm1 IS active).

J2 is a single throw relay for alarm2 functionality.
Pins 13 & 14 form a normally open path (switch is OFF when alarm2 is NOT active and ON when alarm2 IS active).

All of these relay contacts are rated for 3A @ 120V. 3A @ 120V is 360 watts. You pump claims to be 10 watts, so a 3A relay is WAY more than sufficient to drive the pump. Hell, you could drive a March 809 pump with those relays if you wanted to.

You can use either alarm1 or alarm2 for this. It doesn't matter. I will give the example for using alarm1.

Connect the 120V hot line from your power source to pin 5 (you might want to put a 3A fuse on this line to protect the relay in the PID)
Connect the hot side of your pump receptacle to pin 6 of the PID.
Connect the neutral from your power source to the pump receptacle.
Connect the ground to the ground screw on the receptacle.

You have just set up the wiring so that when alarm1 triggers, the pump receptacle will turn on.

Now you just need to program the PID properly.

You are not using the main output of the PID to control this, so the normal set temperature you are used to using on the main display is irrelevant. You need to program the alarm1 parameters for this.

Press [SET] and enter the code "0001" on the PID to get to the alarm parameter menu. Press [SET] again. You will be able to scroll through 5 items now.

"Sv" = is the main control set temp. Irrelevant for you here.
"AH1" = temp value that will cause alarm1 to trigger
"AL1" = temp value that will cause alarm1 to stop
"AH2" = temp value that will cause alarm2 to trigger
"AL2" = temp value that will cause alarm2 to stop

Since we are using Alarm1, you want to mess with AH1 and AL1.

Let's say that you want to keep your water bath in the range of 66-68 degrees. Set AH1 to 68. Set AL2 to 66.

Save the settings by cycling to "End" and pressing [SET].

Done.

The PID is going to be trying to drive the SSR based on the reading from the probe, but you won't have the SSR feeding to anything here so it doesn't matter.

But, if the temp ever reaches 68 degrees, the J1 relay will activate and pins 5 and 6 of the PID will basically be connected together, which will allow 120V to pass through the J1 relay and reach your pump. The pump will come on and start circulating your ice water.

When the temp falls back down to 66 degrees, the J1 relay will deactivate and break the connection between pins 5 and 6, which will cause your pump to shut off.

If you followed all of that, you should be able to see how you could use the alarm functions of the PID to make a 2-stage controller. You just programmed Alarm1 to perform a basic ON/OFF cooling function. You could also program alarm2 to perform a basic ON/OFF heating function. Like... set AH2 to 64 and AL1 to 66 or whatever. Heating will now come on at 64 and stay on until 66.

Or you could use the existing SSR output to perform heating if you wanted to by using the normal set temp value and plugging a heater into the receptacle that the SSR is controlling.

Lots of options on that little PID. The alarm relays are super flexible.

If that didn't make sense, let me know. You will have to do some re-wiring here to make this work, but in the end you can have it set up so that one outlet on the box is for something you want the SSR to control and another outlet is for something you want the alarm to control.

 

[acidrain]

Be aware, this may not work the way you think it will... without valves opening and closing as well, you will set up a convection current, which will flow water through the system whether you want it to or not.
I know because I tried using a similar system for my anodizing tank. It didn't work.

 

[powermd]

Be aware, this may not work the way you think it will... without valves opening and closing as well, you will set up a convection current, which will flow water through the system whether you want it to or not.
I know because I tried using a similar system for my anodizing tank. It didn't work.

I'll just have to run the system for a while to see if it works well enough. Bear in mind there should always be a tendency for the temperature to rise given that the fermentation vessel will be in an environment warmer than the set temp.

 

[powermd]

Thank you for your extensive reply! I'll play around with the settings this weekend and try using alarm modes to operate the pump.

You probably have the PID programmed with the "outY" parameter set to "2". This is the mode where the main control output is set to drive an SSR. In this mode, the JLD612 has two alarm relays available to use.
[snip]

 

[JimmySpeakaz]

Not sure if you ever found the answer to this but I also have the jld612 and I accidentally found a setting in the outy that is not in the manual or anywhere on the web. Set outy to '3'. It will be just on and off. Hope that helps.

 

[powermd]

Not sure if you ever found the answer to this but I also have the jld612 and I accidentally found a setting in the outy that is not in the manual or anywhere on the web. Set outy to '3'. It will be just on and off. Hope that helps.

Yes, I did, but thank you anyway. Does setting the outy to 3 affect the SSR output, or a different output (alarms)?

To solve my problem I played around with some of the SSR output controls (forgot which) with a goal of minimizing the proportionality of the output to get it as close to on/off as possible. It worked well enough to serve the purpose as a fermentation tank chiller. It kept my last brew a rock solid 66F for 10 days. If your way is simpler and more effective, I will use it.

One of the other posters suggested using the alarm outputs instead of the SSR. I went with the SSR because a) I've got one and have nothing else to do with it, and 2) I may use it as a tank heater one day.

 

[JimmySpeakaz]

I'm not sure if my way is easier or not but, I basically set three things. outy, cool/heat and target temp. I set to cool and set outy to 3 and the desired temp and I'm off. I tested it this weekend with an old fridge I got for free and about 3 gallons of water and I was able to hold it at 51F. It floated around 50.7 to 51.3 but I'd say that is about as deadly accurate as you can get. I just picked up some ingredients for Munich using a Bavarian lager yeast. This is the first time I've been able to control my fermentation environment enough to use a lager yeast so I can't wait to see how it turns out. I'm pretty pumped!