Temperature Controlled Grill

[solman]

Hi Solman

I've been taking tips and ideas from your design and hope you don't mind me posting a picture of it with labels and a few questions I have

Firstly, the way I understand your's to work is as follows.

Your LPG/Propane tank connects directly to (A) which I would term as your Gas input. The Gas then flows through the solenoid (C) if it's opened and goes out through (B) which I would term as your Gas Output. (B) is connected directly to your smoker.

Questions I have

1. D looks like a Manual Valve to me and I'm not sure the function it plays in your setup since if D is open and the Solenoid closes, Gas will still flow through D and out B.

2. You mentioned a Safety Valve which I understand to be connected to a Thermocouple which shuts off automatically should the Pilot light go out - Where does it go in your Diagram?


Thanks again for all your assistance and guidance - greatly appreciate it.

1. the PID controls the solenoid valve and turns it on or off. when it's off, the gas flows through D, a needle valve, and the goal is to dial in the needle valve so the smoker temperature gets close to but just under the set value in the PID. for example, if i have my PID SV at 235F, i'll dial in the needle valve (with the PID off) until i can get a steady temperature of around 225F. or if the PID is set to 300F, i can turn the needle valve open a little more so it can steadily maintain 290-ish when the PID is off.

what i recently did with ribs is set my needle valve to around 220F, and PID SV to 235F. then later in the cook i changed the PID SV to 250, then 265, and finally 280, all without touching the needle valve. since the needle valve was still set to be around 220-ish, the higher the PID SV, the higher the temperature oscillation. here's a graph to show what i mean.


the red line shows the smoker temperature. once the PID SV was at 280, it caused a greater temperature change between solenoid valve being on and off. ideally i would've adjusted the needle valve each time i changed the PID SV, but the Auber PID has wifi and i didn't want to get off the couch. :)

2. in my set up, the safety shutoff valve is after B. i guess it could go before A or after B. once it detects flame off, it'll shut off the gas flow so i don't think it really matters where it's placed.

i hope this answers your questions. since i found the original design idea of this set up, i've noticed a few other PID controller designs for controlling propane flow that other people have posted throughout the years. this is by far the simplest and easiest way to do it, in my opinion.