Dual purpose controller??

[mattman7000]

Hello Everyone!
I'm sure this is a question that will probably sound a little dumb to those that have much more experience at this than I do, but I have been scouring the forums to try to find an answer about this idea I had and have found nothing do far. I was basically wondering if there is a way to use one pid controller to heat the BK/HLT and then switch it over to control the fermentation chamber. Would a Ranco or Johnson A419 be capable of this? Or would some other device?

 

[muhteeus]

Shortly, no. But let me explain.

PID is controlled by a characteristic equation based on its error. The error is a function of SP-PV or Setpoint - Actual Value. P - Is the proportional or present adjustment value, which scales the output based on the error NOW. I - Is the integral or past value, which scales the output based on the sum of the error over a past interval. D - Is the derivative or future value, and scales the error based on what the controller "predicts" will happen to the process variable.

So with this in mind... Most PIDs use a "auto-tune" which sets the parameters (P,I, and D) to give you the best "out-of-the-box" control. What this means is that based on the element, type of vessel, wiring, even relays... there are different PIDs that will be calculated (or required).

What this means simply: When you try to swap your controller to control fermentation, you would need to rewire and retune the controller for fermentation. Also, after you are done and want to change back... you would have to rewire and retune for the brewday....

Now, there are ways around this.
-A "gap controller" like the johnson A419 could work, but you would have to change parameters based on heating or cooling.
-A single brew\ferm vessel with heat\cool built in. There are people that make retail vessels that can do this, or you could roll your own... but honestly, for the bottleneck it introduces, and the complexity, you would be better off buying 2 PIDs.

TL;DR: Not really, buy 2 seperate controllers.

 

[mattman7000]

Hey thanks a lot for explaining that, makes more sense to me now. So 2 controllers would be the better way to go. Now for the the device that controls the fermentation chamber, I would like for it to tell my fridge to kick on when the beer in the carboy gets to warm and tell an aquarium heater to start up when it gets too cool. Will I need two controllers for that as well, or is this where a dual controller comes into play? Or would it just be easier to set the carboy down in my cold basement with a heat wrap around it and use a single stage controller?

 

[muhteeus]

Hey thanks a lot for explaining that, makes more sense to me now. So 2 controllers would be the better way to go. Now for the the device that controls the fermentation chamber, I would like for it to tell my fridge to kick on when the beer in the carboy gets to warm and tell an aquarium heater to start up when it gets too cool. Will I need two controllers for that as well, or is this where a dual controller comes into play? Or would it just be easier to set the carboy down in my cold basement with a heat wrap around it and use a single stage controller?

That is where the dual controller (STC-1000) would come into play. But yes, if the basement is cool, you should do that. No sense burning kWh if you have a cool area to put it in.

 

[grathan]

I plan to start out with a single pid. Gonna use it for hlt, herms, kettle, ferm chamber, and also cooking. I don't know much about auto-tune, but I bet I can still use manual mode. The biggest thing is being rated for enough amps on the relays for heating elements.

 

[muhteeus]

I plan to start out with a single pid. Gonna use it for hlt, herms, kettle, ferm chamber, and also cooking. I don't know much about auto-tune, but I bet I can still use manual mode. The biggest thing is being rated for enough amps on the relays for heating elements.

Yeah you can use manual mode. Just keep in mind that you have to adjust the output to set the temp. So for fermentation, you would have to periodically check the temperature of the chamber and adjust the output up or down. Which IMHO is going to be a LOT of work.

If you want to be very cheap about using these, you could use the autotuned PID in auto for your HLT/HERMS (since there is no control on herms just measure the temp of the HLT) and then switch over to manual mode on the kettle and dial up to about 80%+.

 

[grathan]

You saying you can't just set a PID to manual and let it maintain a certain temperature? ISn't that the exact function that a controller does? Or are you saying the cycle time will be hit or miss for only the first time you use it?
http://www.auberins.com/index.php?main_page=product_info&cPath=1&products_id=264

 

[chezhed]

You might investigate this....

http://www.controlproductsonline.com/9102-series-temperature-controllers-p-103-l-en.html

I am affiliated with the manufacturer of this product.

 

[crane]

I plan to start out with a single pid. Gonna use it for hlt, herms, kettle, ferm chamber, and also cooking. I don't know much about auto-tune, but I bet I can still use manual mode. The biggest thing is being rated for enough amps on the relays for heating elements.

Here is what I would do. Autotune the HLT and use PID mode for that. Use manual PWM/duty cycle mode for the boil kettle as you are controlling how rigorous of a boil you want, not the temperature. Then use on/off hysteresis mode for the fermentation chamber because excessive cycling of the compressor will wear it out. This is exactly how I control each of these 3 devices in my setup but I use seperate controllers for each. The only problem I potentially see is building one box that controls both 220V heating elements and a 120V fermentation chamber. Are you planning on having 120V and 220V inputs/outputs connected in parallel and depending on what you are controlling you only plug one set in at a time? If you have an idea of how you are going to wire this you should post a diagram.

 

[grathan]

Plug and unplug. I haven't looked at pid wiring yet, but I assume I can wire it to accept either voltage.

 

[rekoob]

You're making this harder than it needs to be.
Just get two controllers. You can go the STC-1000 route and build your own for a quarter what you can buy a Johnson controller or get one STC and an Aubern PID, still less money than a Johnson.
Don't get me wrong here, please do what you want but make it easier on yourself, that's the goal of having a controller isn't it?
If you have a basement use it... your temps are pretty stable darn stable in the basement most of the time. Very easy to maintain fermentation temps in that range.
I have a dual Johnson controller on my fermentation chamber (no basement), a single Johnson controller on my keezer, and two PIDS on my brew stand (don't use one on the BK).
Mix and match and set it up how you want but try to stay away from disconnecting and reconnecting a PID, it's just not that easy unless you build a controll unit that you can use as a stand alone.
Good luck.

 

[trimixdiver1]

Look at eBay. Watlow makes temp controllers too.