I built this on Father's Day to replace a super ghetto metal box. I had gone with the metal because I thought I could use the case as a heat sink for the SSRs, but that didn't turn out to be such a good idea (box got hot, PID did not like that) The metal is hard to work with, and the result was not pretty.
I saw someone else on this forum make a box similar to this one (probably the same exact box, but I can't find that thread). This toolbox was $9 at Lowes (or HD). I used a dremel with little cutoff wheels for all square cutouts. Round ones were either drill or hole saws.
One thing that makes this box unique is the single PID to control two elements. I have a 3P3T switch that selects which element and thermocouple is being used; the switch has a middle position that selects neither (both off). Because of amperage limitations, I can't run two elements at the same time, so there was no point in 2 PIDs, In fact, If I used 2 PIDs I would probably trip the breaker all the time by accidentally turning both on. This design eliminates that problem. There's an attached schematic in PDF/ZIP for anyone interested.
Two important things to mention here: 1) Although the schematic shows a 4 prong outlet supplying this box, I only have a 3 right now. Soon to be corrected. 2) I'm running thermocouples through a switch. This will create some error due to the way thermocouples work (I do use thermocouple wire tho). Quick testing showed maybe a few degrees, but I have to test more. Probably will switch to thermistors or RTDs.
View attachment Brewing Control Panel Schematic.zip
I saw someone else on this forum make a box similar to this one (probably the same exact box, but I can't find that thread). This toolbox was $9 at Lowes (or HD). I used a dremel with little cutoff wheels for all square cutouts. Round ones were either drill or hole saws.
One thing that makes this box unique is the single PID to control two elements. I have a 3P3T switch that selects which element and thermocouple is being used; the switch has a middle position that selects neither (both off). Because of amperage limitations, I can't run two elements at the same time, so there was no point in 2 PIDs, In fact, If I used 2 PIDs I would probably trip the breaker all the time by accidentally turning both on. This design eliminates that problem. There's an attached schematic in PDF/ZIP for anyone interested.
Two important things to mention here: 1) Although the schematic shows a 4 prong outlet supplying this box, I only have a 3 right now. Soon to be corrected. 2) I'm running thermocouples through a switch. This will create some error due to the way thermocouples work (I do use thermocouple wire tho). Quick testing showed maybe a few degrees, but I have to test more. Probably will switch to thermistors or RTDs.
View attachment Brewing Control Panel Schematic.zip