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Hello Everyone,
I've been planning a DIY control panel for a Dual BIAB system (10 gallon batch, 15 gallon kettles) for some time now and am getting ever closer to making that a reality and I'm ordering components. I have an idea that I haven't seen elsewhere but I can't imagine I'm the first to think of it or carry it out. My plan is to use a changeover switch like the below to select which kettle/element is receiving 240V and which is receiving 120V at any given time in the process. Obviously the best solution would just be to have a 50A service to supply power to it and I can run both kettles off of 240V but that isn't an option currently. The power being supplied to the panel will be from two sources: 30A, 240V and 20A, 120V. The 120VAC is not being broken off from 240VAC supply so I have full amperage available and balanced loading. I'm not mentioning parts of the circuit that aren't necessary to the question but there will be standard safety and control equipment like contactors, circuit breakers, GFCI protection, SSRs, etc.
My process would be to turn on the controller and have 240V going to Kettle 1 and 120V to Kettle 2 at the beginning of the day. Once I reach strike temperature on Kettle 1, I would change the switch to where now Kettle 2 is receiving 240V and Kettle 1 has 120V. At mash out of Kettle 1, I would dough in on Kettle 2 and change the switch so Kettle 1 would have 240V again. I would then boil as normal on Kettle 1. Once the boil is finished on Kettle 1, Kettle 2 would get the 240V to raise to a boil for the rest of the brew day.
See my wiring diagram attached and at the bottom, it is pretty straightforward. Position 1 is for 240V on Kettle 1, 120V on Kettle 2, the opposite for Position 2, and Position 0 is everything is off. Is this a bad idea? Do you see any reason why this wouldn't work? Below are some of perceived pitfalls and ways I hope to overcome it.
I've been planning a DIY control panel for a Dual BIAB system (10 gallon batch, 15 gallon kettles) for some time now and am getting ever closer to making that a reality and I'm ordering components. I have an idea that I haven't seen elsewhere but I can't imagine I'm the first to think of it or carry it out. My plan is to use a changeover switch like the below to select which kettle/element is receiving 240V and which is receiving 120V at any given time in the process. Obviously the best solution would just be to have a 50A service to supply power to it and I can run both kettles off of 240V but that isn't an option currently. The power being supplied to the panel will be from two sources: 30A, 240V and 20A, 120V. The 120VAC is not being broken off from 240VAC supply so I have full amperage available and balanced loading. I'm not mentioning parts of the circuit that aren't necessary to the question but there will be standard safety and control equipment like contactors, circuit breakers, GFCI protection, SSRs, etc.
My process would be to turn on the controller and have 240V going to Kettle 1 and 120V to Kettle 2 at the beginning of the day. Once I reach strike temperature on Kettle 1, I would change the switch to where now Kettle 2 is receiving 240V and Kettle 1 has 120V. At mash out of Kettle 1, I would dough in on Kettle 2 and change the switch so Kettle 1 would have 240V again. I would then boil as normal on Kettle 1. Once the boil is finished on Kettle 1, Kettle 2 would get the 240V to raise to a boil for the rest of the brew day.
See my wiring diagram attached and at the bottom, it is pretty straightforward. Position 1 is for 240V on Kettle 1, 120V on Kettle 2, the opposite for Position 2, and Position 0 is everything is off. Is this a bad idea? Do you see any reason why this wouldn't work? Below are some of perceived pitfalls and ways I hope to overcome it.
- PID Tuning: The PID would change from having full power to 25% power at the flip of a switch. This would make traditional tuning methods nearly impossible, especially if you want to keep tight temperature control.
- My plan for this is to just test and see what happens. Maybe this isn't a big issue and I can stay within a couple degrees.
- I didn't discuss this as it isn't relevant to most of the question but my second option is that this will be a Solo PID from Automation Direct (https://www.automationdirect.com/ad...s/1-z-16_din_size_(sl4848_series)/sl4848-rr-d) that has the option of sending all of the PID parameters on the fly to the PID via Modbus. So I could tune for 240V and 120V and save them as sets of parameters to pass from my DIY controller when I change the switch.
- 120VAC Being Too Weak: Maintaining mash temperature is pretty much the only job the 120V has to do it it ultimately should be fine with 120VAC so I'm not very concerned with this.
- However, I'm planning on using 7000W Heating Elements just to be sure. Note that the Pump and all other devices outside of the elements would be on the 120V circuit. The element itself has 14.6A current draw on 120VAC so I will be fine on my 20A circuit
- Quality: I'm just not sure on the quality of the switches that I can find. Some people say that they work great for their applications of switching 50A RV loads from generator to shore power and others question the quality.
- My plan is to test these beforehand as best as I can and have a spare handy. Theoretically it should last a long time since I'm at max putting 30A through it but time will be the best judge of that.
- Confusion on System Operation: This could be a potentially confusing to someone who might be familiar with electric brewing since it is uncommon as generally the selector switches are for choosing which element gets power, not from which source the power comes from. All of the wiring and plugs will be sufficient for 240VAC/30A using L6-30 plugs and 10 AWG wire. The Red wire will be either Hot 2/L2 of 240VAC or the neutral for 120VAC. I will need to figure out a good way to represent this.
- Timing: It will make for a busy brew day and a longer one but I'll end up with two unique beers with maybe two more hours of time. I could go longer than I need to on my mash for Kettl1 while I'm chilling the wort or finishing up on Kettle 1 but that won't be a big issue.