Johnson A419 Temperature controllers

[juliobrewer]

Hi all,

I was wondering if anyone out there has had experience with programing above said controllers. I`m having a problem with getting them to cool in one degree increments.

E.G. we set the set point to 20 degrees Celsius after knocking out wort in the FV and then the controller will cool to 18 instead and when the temp rises to 21 again it will cool down 2 degrees instead of 1.

I`ll get my manual out with the programing of it later but off the top of my head the differential is set to one and everything is programed as it should

If anyone has any advice I would greatly appreciate it.

Cheers,

Dave Woodward
Tofino Brewing Co.

[gitchegumee]

Are you sure that the controller is actually keeping the solenoid open when it drops to 18? There is often an overshoot (or "undershoot") of your setpoint due to thermal lag in the system. For example, when the probe detects 19, the controller should shut off. But the beer in the tank is already on the way to 18 and the convection currents, conduction to the probe, and cold glycol caught in the jackets very often (if not always) contribute to an undershoot. I've seen most small breweries experience this problem with any type of controller/probe. There should be a green light on the controller that shows the status of the solenoid. Lit when energized. Otherwise, programming this controller is quite easy and I doubt you've screwed up anything. Sometimes you just have to live within the limitations of your equipment. I do with my A419. Fortunately, I have them on my walk-in and my glycol chiller--not my fermenters. Good luck!

[Ray Hodge]

If your differential is truly set to 1 deg. then the only thing that might help you is to switch to Farenheit as there would be less actual temperature movement to actuate the on/off function. I have older CAL controllers on my ferms and was able to get ahold of a real programming protocol for them, which allowed true cooling operation, a tighter band and better resolution. I am able to read .1 deg F and adjust to a .5 deg band (temp between on and off) and I still get some overshoot, but it is well within reason. If you don't get satisfaction you might think of new controllers. Cheers!

[juliobrewer]

Hi again,

The energizer light stays on when the solenoid stays open for the run, cools down 2 degrees instead of one despite the set point only being set to one in the controls. From what i`ve observed the controller shuts off exactly after cooling two degrees despite the program being accurate. This was been cause quite a swing in the temp ranges which gives me quite a headache..

I`ll give switching to Fahrenheit a go at the end of the week when we`re not cranking out the brews and see if this makes a difference.

[Roger Greene]

It could be the short-cycle delay. Check and see what the ASd is set to. If it is set to let's say 10, then no matter what the temperature, it will not open again for 10 minutes.

[Natrat]

Hey Dave,

The problem with the A419 is that although it is digital, it is only an on/off cutoff switch.

I would recommend upgrading your fermenters and brights to some sort of PID (proportional-integral-derivative) controller. There are lots on the market, RKG, Love, Red Lion...Johnson controls has their TE-6000 series, but it's really not aimed at brewery installations, though I have seen it used.

Not a big job or a big expense to retrofit your existing system. Well worth it IMHO.

Hope that helps. Let me know if I can be of any more help.

Nat

[gitchegumee]

Natrat, PID's won't work with solenoids. Need modulating valves for that. Perhaps a positioner, air source, 4-20 current to pressure.... Likely to be expensive unless you know something I don't about newer equipment. What are you using? Would be nice, but I think a brewery could use many other toys before PID control on fermentation tanks. On-off control can be tuned quite well without excessive cycling for quite adequate temperature control. Although maybe not with A419s.

[Natrat]

Phillip,

I've used PIDs to control solenoids. It's just a matter of setting up the algorithm to have a pulse-width modulation. Given a decent solenoid, it seems to work quite well in fermenter cooling.

I agree that PID is really meant for modulated controls, but they do work well in on/off applications as well, as the device can "learn" when to switch off devices in advance on applications where the measured gradient continues to change after shut down.

I learned about the PWM from a gentleman who was using a PID to control the burner on his hot air balloon. While manual controls for his balloon were variable, the digitally controlled burner needed to light faster, and only worked on full on/full off. He used PWM to "stutter" burn his jet, which resulted in a controlled curve of temperature.

Pretty cool stuff, and applicable in the brewery.

Nat

[beermkr]

I think you will find that the controller shuts off as soon as it hits 18 degrees. I have the same controller on our beer trailer and it does the same thing. Basically it cools to a FULL 1 degree below the set temp and that often causes an overshoot to 2 degrees for a few minutes (in my case it is an air conditioner).

The Fahrenheit should narrow your band down a lot and is really your only option with this type of controller.

R/

[juliobrewer]

Thanks for everyones advice.

After kegging and cleaning the last two days i'll start some trials with the controllers tomorrow and can hopefully get it dialed.

Dave Woodward

Tofino Brewing Co.

[gitchegumee]

Natrat, that is so cool. Learn something new every day. I'll have to look up that one and see if I can make it work. "digital" analog. Thanks!

[tariq khan]

Hey Dave,

I agree with Ray. I had 3 Fv's with the 419's (Fahrenheit). I needed to get one replaced and the service guy showed up with a Celsius, so now I have 2 set to Fahrenheit 1 to Celsius. I have the same issue as you. I'm just living with it but yeah I prefer the fahrenheit.

T

[Woolsocks]

I LOVE the A419, but not for controlling fermentation, since you can't set the differential tight enough. Use your A419s for your keg fridge, beer cooler, etc. and get some tighter controls for your fermenters. Failing that, you're better off in °F (it hurts me to say that) since they're smaller.