Can I build a PID controller box cheaper than a Johnson/Ranco?

I want a temperature controller that I can use for multiple elements: aquarium heater, electric element, refrigerator. They are all 120 V and less than 15 amps.

Can I build a box out of Auber or other PID controller, plus thermocouple, outlets, etc (do I need a separate SSR?) for less than $80?

twd000 said:

I want a temperature controller that I can use for multiple elements: aquarium heater, electric element, refrigerator. They are all 120 V and less than 15 amps.

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Are they all less than 10A? If so, then the ebay aquarium controller is probably the cheapest solution. $35-$40 a pop when completely assembled.

IF that...you probably have some of the stuff laying around already!

I doubt 10A would work to control an electric heating element unless it was lower wattage than is likely useful for brewing purposes.

weirdboy said:

I doubt 10A would work to control an electric heating element unless it was lower wattage than is likely useful for brewing purposes.

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Yeah... for the fridge and aquarium heater, it would work, but not suitable for a heater larger than 1000 watts.

Plus, more than the load, the amount of switching needed for recirculating mash systems makes mechanical relays non-ideal.

I mean, you could use the aquarium controller to drive an SSR if you have a load greater than the controller itself can handle, but I wonder how long the thing would last with the relay inside of the controler turning off and on a bunch of times in a hour.

yeah, I 'd like to use this device to control my 1500 W heatstick (to set-and-forget mash temps etc.). So the 15 A is a pretty firm requirement.

Is there a basic PID you recommend to build this around? I see Auber has a 1/32 DIN for $36. What other gear would I need? (besides thermocouple and basic wiring stuff)

twd000 said:

yeah, I 'd like to use this device to control my 1500 W heatstick (to set-and-forget mash temps etc.). So the 15 A is a pretty firm requirement.

Is there a basic PID you recommend to build this around? I see Auber has a 1/32 DIN for $36. What other gear would I need? (besides thermocouple and basic wiring stuff)

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Well.... it's going to be pretty expensive way to heat water to a desired temp, but once you have your heat stick assembled (which is what? $30 or 40?), you'll need (all prices are approximate and don't include shipping):

PID: $35
Liquid tight temp probe: $20
SSR+heatsink: $10
Some sort of bulkhead to install the probe in your kettle: $10
Enclosure: $15
Power cord: $10

and then maybe anouther $10-$15 in misc items like receptacles or cord-grips, depending on how you want to get power in and out of the box.

You'll be close to $150 for the whole project (heatstick + controller box).

Walker said:

Well.... it's going to be pretty expensive way to heat water to a desired temp, but once you have your heat stick assembled (which is what? $30 or 40?), you'll need (all prices are approximate and don't include shipping):

PID: $35
Liquid tight temp probe: $20
SSR+heatsink: $10
Some sort of bulkhead to install the probe in your kettle: $10
Enclosure: $15
Power cord: $10

and then maybe anouther $10-$15 in misc items like receptacles or cord-grips, depending on how you want to get power in and out of the box.

You'll be close to $150 for the whole project (heatstick + controller box).

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Oh... and don't forget... if you use the Ranco or Johnson, you'll still need some way of putting the probe into the kettle in a liquid tight manner.

It'll cost about the same as using a ranco and a thermowell for the ranco probe in the end, I would guess.

I'm going to backpedal on the earlier statement.

You can build the aquarium controller, which is functionally equivalent to a ranco or johnson dual-stage controller for $35 or $40. If you add a cheap wall-wort (or hijack an old cell-phone charger), and use that controller to drive an SSR, you can build this thing for $60 or so (plus the cost of the heatstick).

You still have the issue of the mechanical relay being used somewhere in the design, but that issue exists for the Johnson or Ranco, too.

The probe that comes with the aquarium controller is supposed to be submersible, but would probably be better used inside of a thermowell.

At any rate... since you can build a basic temp controller like a johnson/ranco for cheaper than a johnson/ranco, even with the added expense of an SSR to go beyond 10A, then you have to be able to do this cheaper than buying a johnson/ranco.

thanks for the solid advice already

let me tell you a bit more about my system

I am not setting up a HERMS or all-electric rig

I brew on the sideburner of my propane grill, which is adequate, but takes too long to get 5 gallons up to mash temp, and has a somewhat anemic boil

So I am going to supplement with 1500 W heatstick, regardless of whether I control it manually, or build or buy a controller

So I figured if I am going to build a heatstick, why not augment with a controller, so I can use the propane to get close to target temp, then let the heatstick dial in the mash/sparge water temp, and make any mash temp adjustments.

And if I'm going to build this controller that would only be used on brew day, why not make it portable so I can can use it to control fermentation temps post-brew?

hopefully that makes my objectives more clear

All that being said, what SSR would you recommend with pair with my PID, if I went that route?

twd000 said:

All that being said, what SSR would you recommend with pair with my PID, if I went that route?

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You can get 25A SSRs on ebay, shipped, for $6. For what you are doing, you might not even need a heatsink, but those are only another $5.50 on ebay if you want to get one.

SSR: http://cgi.ebay.com/Brand-New-Solid...333?pt=LH_DefaultDomain_0&hash=item27b8db29a5

Heatsink: http://cgi.ebay.com/New-Heat-Sink-S...095?pt=LH_DefaultDomain_0&hash=item45f926b1cf

Combo Package for $12.50: http://cgi.ebay.com/Solid-State-Rel...060?pt=LH_DefaultDomain_0&hash=item5d2c720b6c

Great advice here. Thank you. I'm trying to decide what I want to do too. I'm also looking for a reasonably priced alternative. Seems like the Auber PIDs are the best price for the PID package but are ~ 2x as much as the aquarium controllers. But... you get a nice display and good PID logic. This one: http://www.auberins.com/index.php?m...s_id=3&zenid=adc4a69fe00c8f7f4b86b0aea259d82e coupled with Walker's recommended SSR + Heat sink seems pretty awesome.

wow... thoughts on this?

http://cgi.ebay.com/New-Dual-Digita...emZ280574783198QQcategoryZ66991QQcmdZViewItem

ThePearsonFam said:

wow... thoughts on this?

http://cgi.ebay.com/New-Dual-Digital-F-C-PID-Temperature-Controller-Control_W0QQitemZ280574783198QQcategoryZ66991QQcmdZViewItem

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DON'T BUY IT. At least not yet.

I am helping a guy here in Chapel Hill design a system, and that's the PID he bought. He received it a couple of days ago, only to find out that the description in the listing appears to be wrong on at least one critical point.

Here's the problems with that PID.

(1) The title says "F/C PID", which we took to mean that it was usable in either Fahrenheit or Celsius. However, it appears that the PID is actually Celsius only. That's inconvenient, but not the end of the world.

(2) No where in the written description does it say what the power supply is for the PID. But, the sticker on the side of the PID indicates that the power supply needed is 220V. If you are building a 240V system, then this is not an issue. If you are building a 120V system (like the guy I am helping)..... different story. Now, the guy I am helping bought this same PID from a different seller for an even better price ($21.50 total), and there was no pic of the sticker in that listing. We had no idea what the power supply was. We asked the seller via ebay messages, and he responded that it could work on 120V. Now that we have the PID, it has the sticker on it indicating a 220V power supply. The guy still insists that it will work on voltages as low as 85V. I am actually inclined to believe him on that, because my PID (a "Tet612") as well as the PIDs from Auber also work on a range from 85V to something like 260V. SO... the voltage might not end up being a problem, but it's something to think about if you are intending to build a 120V system.

(3) AND THIS IS THE CRITICAL PROBLEM... the listing indicates that it has "Voltage pulse output: 0/12V". This would be an SSR control signal. However, this appears to be totally false. The first clue on this is that the sticker says "OUTPUT RELAY", and not "OUTPUT VOLTAGE PULSE". I found 4 or 5 guys selling this same PID, and one of them had a pretty nice manual for the PID available for dowload. The manual explained the meaning of the "CODE" on the sticker.

The sticker CODE is FK03-M*AN

When you look through the manual I found it decodes this product code as:

F = PID with autotuning (reverse action)
K = K-type thermocouple input only
03 = range of operation is 0*C to 400*C

M = Main Output is a Relay - this part of the CODE needs to be a "V" for the "0/12V" SSR control to be available

A = alarm #1 is a high deviation alarm
N = alarm #2 is not present


We are exchanging messages with the seller and trying to get him to answer questions, but the one we are dealing has as much of a problem speaking English as I have speaking Chinese, so there is some difficulty here. If I get the thing resolved and the PID actually does work, I will respond here, but as for right now... be wary. This thing has one inconvenience (Celsius only), one potential problem for 120V systems (we will find this out), and one potential deal breaker if the thing can't drive an SSR.

To the OP,

It sounds like it would be cheaper to get a beefier propane burner than to build up what you are looking for.

Sawdustguy said:

To the OP,

It sounds like it would be cheaper to get a beefier propane burner than to build up what you are looking for.

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He wants to control a fridge with this when he's not brewing, and the electric element when he is brewing.

Propane might not work so well with the fridge (or the aquarium).

Wow... thanks for saving me the trouble. Guess I just need to get a Love or Auber if I want the nice digital display.