PID temp controller?

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rod734

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Iv been looking at a PID temp controller on ebay, looks just like the one I got for my freezer fermenter conversion, but it has 30a relay. Any reason this wouldn't work to controll heating elments in a boil kettle? I'm a little skeptical about a 30a 220 contacter in this small a pkg. I'v been thinking about putting 2 3000 w elements in my kettle and having one manually switched so I can cut it out after boil has started. Any thoughts on this?
 
rod734 said:
Iv been looking at a PID temp controller on ebay, looks just like the one I got for my freezer fermenter conversion, but it has 30a relay. Any reason this wouldn't work to controll heating elments in a boil kettle? I'm a little skeptical about a 30a 220 contacter in this small a pkg. I'v been thinking about putting 2 3000 w elements in my kettle and having one manually switched so I can cut it out after boil has started. Any thoughts on this?

I have not seen contacts rated that high on pid's. That doesn't mean its not possible. Try to verify it with the manufacturer.

I would consider building a pulse width modulator controller instead of a pid. Boil controll really does not need temp feedback and a pwm will save you from an extra hole in your kettle for the probe. Plus I found it to be quite a bit cheaper.

I built Walker's circuit. You can search my threads to find it if you're interested.
 
I would consider building a pulse width modulator controller instead of a pid. Boil controll really does not need temp feedback and a pwm will save you from an extra hole in your kettle for the probe. Plus I found it to be quite a bit cheaper.
If you want to keep it simple and don't know electronics a PID is still a reasonable way to go to control the boil in the boil kettle.

No need to put a hole in the kettle for the boil temp probe either, it doesn't have to be in the kettle at all. In fact, you don't need to use a temp probe at all. Just use a fixed 1 cent resistor.

I considered building a PWM circuit instead of using a PID for my setup to control the boil, but once you factor in the parts including a waterproof control, the price difference is negligible. Not to mention the extra work to save maybe $10-20.

There are other advantages too to actually putting the temp probe in the boil kettle: You can set the PID to 208F and never have unattented boil overs. It'll simply ramp up to just before boiling, an alarm can be set to go off then and then you go into manual mode and watch for boil overs.

Kal
 
kal said:
If you want to keep it simple and don't know electronics a PID is still a reasonable way to go to control the boil in the boil kettle.

No need to put a hole in the kettle for the boil temp probe either, it doesn't have to be in the kettle at all. In fact, you don't need to use a temp probe at all. Just use a fixed 1 cent resistor.

I considered building a PWM circuit instead of using a PID for my setup to control the boil, but once you factor in the parts including a waterproof control, the price difference is negligible. Not to mention the extra work to save maybe $10-20.

There are other advantages too to actually putting the temp probe in the boil kettle: You can set the PID to 208F and never have unattented boil overs. It'll simply ramp up to just before boiling, an alarm can be set to go off then and then you go into manual mode and watch for boil overs.

Kal

I didn't mean to imply that a PID should not be used just that a PWM is an option to consider. I didn't think of the advantages of a chilling thermometer and pre-boil alarm. Sorry if I brought this off topic a bit.
 
Use the relay in your PID to drive larger relay(s) that can handle the load.

Iv been looking at a PID temp controller on ebay, looks just like the one I got for my freezer fermenter conversion, but it has 30a relay. Any reason this wouldn't work to controll heating elments in a boil kettle? I'm a little skeptical about a 30a 220 contacter in this small a pkg. I'v been thinking about putting 2 3000 w elements in my kettle and having one manually switched so I can cut it out after boil has started. Any thoughts on this?
 
Link to PID would be helpful.

If I can figure out how to post a link I will. The pid is on ebay and looks just like the 110v/10a I got for a fermenter only it is 220v/30a.
I think the only way one of these would work is to have two elements with one manually controlled so you can have it on all the time during the boil and the other controlled with this pid. These things are only on or off so if you set it high enough to boil it would never shut off and if you set it low enough to shut off it would never boil. So if I set it right at boiling temp to assist the other element to reach boiling and shut off, the other element will keep the boil going. Am I thinking right?
 
Note: If you're concerned about the PID relay handling the load, and you want to use the PID relay to control larger relays, then you probably want the 12VDC version of this widget...
 
That is not a PID, despite what the auction title says. If you read the instructions way down the page you'll find that it is a thermostat with hysteresis (they call it backlash). Not a PID.

Notice their unusual use of English. Power input is called Fire, etc., etc.

+1

It's a thermostat and not a full-blown PID.
 
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