JLD-612 for Charcoal Smoker Temperature control

[golfwins]

Hello Everyone,

I'm new to the forum as well as the PID technology. I'm having a little bit of a hard time wrapping my head around this so that I can understand what I need to purchase. I'm trying to use the PID to monitor a PT100 Thermocouple and use that data to control a blower/fan to the fire box. I'm not sure how to program the PID so that once the smoker gets close to the Target Temp the PID slows down the fan, or pulses the fan so that it doesn't overshoot the Target Temp. Is it better to get an AC PID or DC? If I get DC, is it difficult to wire compare to AC. I really appreciate any feedback any of you have to offer. I'm sure I've left out valuable information so please ask away. I did plan on using an SSR because I've seen it used in other plans although I'm not entirely sure what it's for.

Thanks for your help,
Jeremy

[golfwins]

Noone? Here I thought this was a simple setup. I mean simple for you guys. Can someone tell me what makes this difficult?

[richiem]

Probably, DC will be best, using a DC-type SSR to run a small 12VDC computer-type fan. Buy a 12-14V DC power supply like the ones used to run car stereos on a test bench -- they're called "battery eliminators." A supply with about 3A output will be plenty. Radio Shack used to sell them, and you can find them online. The power supply will then power everything. Get the JLD612 DC version, a PT100 sensor (or use a K type thermocouple), a DC SSR, and a 12V DC fan appropriate for your firebox -- probably a small one as won't have to move a lot of air.

Lots of variables here -- an important one is the relatively long response time of the system to on and off operations. But I think a PID control will work OK. In the end, it may be that just a simple thermostat-type on/off control will work fine, and the PID controller can do that too, so either way, the system will work for you.

The PID operation will control the on to off ration of the power to the fan, so that when the temp is very low compared to the set value, the fan will run continuosly, and as the temperature approaches the set value, the fan will pulse on and off, and then eventually be off for long periods until the temp drops again.

If you are not familiar with wiring such systems, then finding local help may be required.

[golfwins]

Thanks Richiem! I was hoping you would get around to answering. I've seen you answer pretty much everything else here. So, I'm ordering the JLD612 DC version, and the 25A SSR DC in DC out. I'm also going to get the PT100 ETC-CB-PT2M. I want to use a 10cfm fan. I'm not sure how many CFM's this fan is: EFAN-D12032. I can buy it online if it's not the correct cfm.

"The PID operation will control the on to off ration of the power to the fan, so that when the temp is very low compared to the set value, the fan will run continuosly, and as the temperature approaches the set value, the fan will pulse on and off, and then eventually be off for long periods until the temp drops again."

This is exactly what I want. Do you know what setting I need to adjust to make it start slowing down at let's say 20 degrees before Set Point. I want to slow the fan down so that I don't over shoot the Set Point by much. And then once it get's to the Set Point. It will drop a few degrees before it starts pulsing again. I've seen others do it online, but no one has really shared their programming of the PID. I really appreciate your feedback. If you don't mind, could you make sure I'm getting parts that work with each other. Thanks again!

[richiem]

Using auto tuning should tweak the various parameters for you, so that the overshoot is minimised. There will be some, but by slightly adjusting your set point, this probably can be minimized. Much fooling around will be needed, though.

[golfwins]

Thanks for your help! Marco told me someone here would probably help. Once I started reading the forums, i figured it would be you. I'll get this ordered and put together and let you know how it goes. Thanks again!

[Tech_Marco]

Yes,Rich is the best who know PID temp controller the most. I don't know what to say and a salutation won't be enough for my gratitude toward to his help and sharing. He is patience and he is knowlegeable. Plus, he didn't get pay for doing this.

Thank you Rich!!

Marco

[WOLFTRACK955]

HERE YOU GO BOYS !!
this is just a littel note on how i worked around this problem for smoker or cooker

take the air flow that you think or worked out that you need and then dived it in half then buy 2 fans that size .
stager j1 and j2 like 10* so set point 250 j1 on 240 off 245 j2 on 235 off 240 so both fans are on till you get close to set point and then
j2 goes off then j1 slows to set point and it j1 can kept temp if knot the j2 kicks in to help
cory

[Tech_Marco]

You sure this thing won't blow?! It look like to me that it's a 'nuke'

Anyway, I'm glad that it work out and thank you for the support from Rich!


Marco

[richiem]

@cory -- great solution -- can't argue with what works; I think your way would be great for a bigger rig. For a small smoker, I think a single fan solution will be OK.