Question for PID setup experts...

S

Steve Sessums

Joined
Jan 17, 2021
Messages
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Hi guys. I have been following old post that no longer have pictures in the photo bucket which would have probably help me tremendously. I set up one of my forges to run on a PID, with a low pressure gas bypass to keep my forge running when the PID shuts it off . I have two potentiometers hooked up to the fan like I have read in the forums so that one set on high would energize when the solenoid for gas does, when the PID says to do so. 120v back feeds from one potentiometer to the other and energizes my gas solenoid before any command from my PID right now and I dont know a way around it. Well I thought of one way, is to use a 12v solenoid instead of using an SSR with a 120v solenoid and get them off the same circuit and not be tied together and back feed electricity. What am I missing from the blue print which I'm not able to see with the old forum post? I have read that it's not absolutely nessassary to lower the fan speed when the PID goes off, but to tell the truth I think its part of a cool factor. Any help is appreciated and I wouldn't know where else to go for help.
 
This was tested and discussed in the past and most everyone just removed the second fan speed control. It didn't really seem to make any difference. Just adjust the fan with the single speed controller to run the forge efficiently when the HIGH solenoid is open. When it goes to LOW, the extra air really doesn't matter much at all. Most folks who built my Two-stage Burner system adjust the HIGH and LOW to be about +/- 50° to 100° of the target temperature. The change in air balance for that small 100° or 200° swing is miniscule.

Now, if the power feedback is the only issue you have, just put a diode in the problematic wire.


This is Nick Anderson's plans. He used the two fan controls, but you just leave the "C" one out.

ePnxuIN.jpg
 
There should be a needle valve in the HIGH line. It can be on either side of the HIGH solenoid. Simplest place in your setup is to place it right after the MAIN SHUTOFF solenoid.
 
I used a switch to turn off the bottom solenoid as my main shut off and the ball valve instead of a needle valve to regulate high pressure. I’m used it last night on an initial start up and it worked great. If this was your idea, you had a really good one. One last question if I may... If you use, and I don’t know that you do use an Ink Bird 106 PID, what is a good hysteresis setting to start off with and go from? And are there any other PID settings to fine tune for this set up? I’m going to do this same set up on my other forge only with a switch instead of PID to bring forge welding temp back down to idle quickly, like I had also read about on the forums.
 
The switch is fine for te ON-OFF function of the gas ( and power failure protection). The ball valve is the main shut-off. It should be turned of when the forge is not running. It is insufficiently regulated to use as a fine tuning valve, and even if you can get it set right, you will have to re-adjust the burner every time you shut it off with the valve. You still need the needle valve between the main shutoff solenoid and the HIGH solenoid. Just unscrew the nipple from the TEE and put it there.
 
G
Stacy E. Apelt - Bladesmith said:
The switch is fine for te ON-OFF function of the gas ( and power failure protection). The ball valve is the main shut-off. It should be turned of when the forge is not running. It is insufficiently regulated to use as a fine tuning valve, and even if you can get it set right, you will have to re-adjust the burner every time you shut it off with the valve. You still need the needle valve between the main shutoff solenoid and the HIGH solenoid. Just unscrew the nipple from the TEE and put it there.
Click to expand...
Got you with the fine tuning for every time
 
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