Pid controller for presto pot

[Thembonez]

I’ve done a search, but it’s like a needle in a hey stack. Has anyone done a turtorial on how to use a pid for temp control on a presto?? A link or summary is greatly appreciated.

[bryanmc]

The hardest part is mounting the thermocouple. 

On mine, I used a piece of 1/2" wide 1/8" thick metal and secured it diagonally across the bottom of the pot.  I ground the ends narrower so they would fit between the feet and the pot.  Then I drilled a hole in the mount strap at the middle of the pot and mounted the thermocouple through the hole so it was in contact with the bottom of the pot.  I also used a drill to make a little divot in the bottom of the pot where the tip of the thermocouple sits and used a tiny bit of computer heat sink compound (artic silver or similar) on the tip.  So far it's worked perfectly.

[Thembonez]

One question I have is, how do you run the power through the control then to the pot? You got your power into the control, then do you just plug the normal presto control into the output of the pid? If that’s the case what do you set the presto t-stat at? Max setting?

[bryanmc]

I took the presto thermostat apart and just used the connectors that slip over the prongs on the pot.  Just cut them off with some wire connected to them so you can solder them to the power leads.

[dlaery]

You will need to find out how much current the pot pulls. most likely you will need to turn the pot power through a Solid State Relay SSR.

then a fuse  because most PID turn on a SSR because the current going through the PID will over heat it. I have never melted plastic but use them for other applications. I had a PID that was suppose to take 10 amps but it didnt so I put a SSR and fuze. If it is 220 you would need 2 SSR and 2 fuses.  

[Thembonez]

The more and more I dig into this topic, the more and more variables their seems to be. I do plan on using a ssr, but that will be addressed down the road. Bryanmc, do you happen to have any images of your setup. Trying to draw a visual, but their is room for interpretation. More specifically the wiring to the pot.

[Baitjunkys]

leave the presto controller alone, just hook the pid to a outlet and plug it in, this gives you a 400 degree fail safe, turn the presto controller on maximum temp.  It is not difficult by any means, I have done a bunch of them. My suggestion use a high quality J type thermonuclear, the ks suck i have found over the last few years. 

[Baitjunkys]

Presto draws 12 amps, A contactor works better then a ssr IMO, ssr is high frequency and makes the shop lights flicker. And the chinese ones are super unreliable.  plus a contactor will do 120 or 240.

[Thembonez]

12 minutes ago, Baitjunkys said:

Presto draws 12 amps, A contactor works better then a ssr IMO, ssr is high frequency and makes the shop lights flicker. And the chinese ones are super unreliable.  plus a contactor will do 120 or 240.

I have to apologize I’m not sure on what a contactor is in this application. If you don’t mind be asking what your setup consist of for your pid. And possibly links to any components. Like I’ve mentioned before you can look this topic up and go a multitude of different directions trying to achieve the same end result.

[Baitjunkys]

https://en.wikipedia.org/wiki/Contactor

https://www.amazon.com/Packard-C230B-Pole-Contactor-Voltage/dp/B001KGSJ74

 

Edited December 7, 2017 by Baitjunkys

[Thembonez]

So Your simply replacing the ssr with this contactor if I’m understanding correctly. After that would all other components stay the same? The source I’m trying to base mine off of is here 

 

if I swapped out the ssr for a contactor would this setup work? Reason I like this guys setup is eliminates an extra plug in to power the controller itself. This is all new to me, so if I’m overthinking this that’s why I’m here, for the help.

Edited December 7, 2017 by Thembonez

[Baitjunkys]

Put your hot wire to the contactor, Jump from it to the pid, Plug controller into wall, plug presto to controller, One circuit that is it.

[bryanmc]

2 hours ago, Thembonez said:

Bryanmc, do you happen to have any images of your setup. Trying to draw a visual, but their is room for interpretation. More specifically the wiring to the pot.

 

Here's how mine is wired.  This diagram was for a Lee pot obviously but the wiring is the same.  I did put a switch on the hot lead to shutdown all the power to the pot and pid.  I use an SSR and don't have any issue with my shop lights flickering (maybe because they're led).  Everybody will have a little different way of doing it, mine works for me.  I used the pid shown in the diagram.  Look it up on ebay, the pid, ssr and thermocouple was 30 something dollars.

pid-wiring.pdf

Edited December 7, 2017 by bryanmc

[Baitjunkys]

Probably so on the leds, I just got away from the ssrs when i built the hose machine, I replaced to many of them prior. They work, Most of the time.

 

[Thembonez]

Ok, I test ran my pid today with my presto. Started good till about the 3 min mark. Then my power cable coming into the pid controll box started smoking! I quickly killed the power and unplugged. I felt the box to see if anything seemed warm and there was no problem there. Opened it up checked out wiring and nothing else was scorched or melted.  I’ll mention that I’ve tested this unit with a light plugged into it several times without incident. Any ideas as to what was going on why I melted my power cable??

[Baitjunkys]

Is the load on the pid or a ssr?

[Baitjunkys]

 If you melted the power cable it couldnt take the load, what awg was it. Needs to be 14 at minimum.