Dual eBIAB 10 Gallon Batch with Changeover Switch for Selecting which Kettle Receives 120V and which Receives 240V

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Bryce Brewer

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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.

  1. 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.
  2. 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
  3. 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.
  4. 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.
  5. 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.
Thanks in advance for the help, I'm looking forward to getting this project off the ground. I tend to be pretty wordy so there aren't questions so hopefully it wasn't too hard of a read. I think a design like this can work really well for a dual BIAB brewer or someone that wants to do back to back batches without upgrading their service to 50A. Cheers!

Changeover Switch Wiring Diagram.png
 

Bobby_M

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Before I contemplate the rest of the project, my first comment is that I don't think that PID has a manual mode (PWM) to regulate boil intensity.

Unless you plan to sparge, 10 gallon batches don't fit in a 15 gallon kettle for BIAB.

Another question here is what does your double batch timeline look like? I agree that 120v is enough to maintain mash temps, but the timeline is generally:

15-20 min initial heat up (full 30amp load).
60-90 min mash (lower load fine)
10-15 min ramp to boil (full 30amp load)
60-90 min maintain boil (60-70% of 30amp load).

I'm curious what time offset would actually work to do a side by side. I suppose you can start heating water for batch #2 on 120v but that ramp time is going to be at least an hour. I would start with some graph paper and figure out what the two kettle's time/temp schedules would look like.
 
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Bryce Brewer

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Thanks for the quick response Bobby, I was hoping you would be one of the guys that jumped in on the topic.

The controller does have a manual mode that I believe I will be able to change an output percentage to say 70% when boiling. It is somewhat read between the lines for me on that at least but I believe that is the case. So basically if that is true, I will change from PID to manual and set the output percentage to whatever I determine to be an appropriate level when boiling.

On the question about sparge, I do plan on sparging so that won't be an issue. Typically I'll bring most of my water up to temp and then transfer out what I need to a cooler to hold until after the mash.

The simpler option would be to do a selector switch between kettles and just insulate through the mash. Then I just would change to Kettle 2 during the mash of Kettle 1 to get to strike, switch 240V back to Kettle 1 to get to a boil while Kettle 2 is mash resting, then back to Kettle 2. So basically a similar concept but instead of a temperature controlled mash, it is a rest. I haven't gotten into complicated mash schedules so that technically should suffice and I could always reduce volume and top up with sparge water if I wanted to. But I guess I like to overcomplicate things, that is in my nature lol.

I have sketched out the timeline for what I think the brew day will look like. There are of course tons of caveats in here and this is a gross oversimplification but I kept it pretty simple to keep it at a high level with just 30 minute time steps. You'll notice time 0:00 is at dough in because I'll have it setup to go the night before and will start the heating of water before I get there.

Kettle 1Kettle 2
TimeAction 1Action 2Action 1Action 2
0:00​
Dough InChange 240V to Kettle 2Heating to Strike Temp
0:30​
Check Gravity & PH
1:00​
Check Gravity and Mash OutHeat to BoilDough InChange 240V to Kettle 1
1:30​
At BoilCheck Gravity & PH
2:00​
Check GravityCheck Gravity and Mash OutHeat to Boil
2:30​
End of Boil, Chill WortChange 240V to Kettle 2At Boil ~2:45
3:00​
Gravity Draining Into FermenterCheck Gravity
3:30​
End of Boil, Chill Wort
4:00​
Gravity Draining Into Fermenter
 
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doug293cz

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PID tuning shouldn't be an issue, as you only plan to use 120V when holding mash temps using PID mode. If 100% power is too much at 240V when ramping heat, you can use manual mode to reduce the power, and use one of the alarm relays to turn off the ramp when the set temp is reached.

Do you have a link for the selector switch you are planning to use?

Would be a good idea to put the full schematic up for review when you get it done. Multiple pairs of eyes can help catch things you overlook.

Brew on :mug:
 
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Bryce Brewer

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That’s a good point Doug, I’ll just be using the PID capabilities with 120V so I won’t need it for 240. Don’t know why I didn’t put that together!

I do have a link for the changeover switch in my original post, the way it shows up on HBT is like an ad almost so you might have just scrolled past it. It’s right after my first paragraph but here it is again for reference:


I’ll post the schematic when I get done for sure, just to double check. When I get back on my computer tomorrow I can post my simple one line description of how the power is routed. Eventually I’ll want to get to each connection detail and ideally do a schematic like I have seen from other people.
 

doug293cz

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That’s a good point Doug, I’ll just be using the PID capabilities with 120V so I won’t need it for 240. Don’t know why I didn’t put that together!

I do have a link for the changeover switch in my original post, the way it shows up on HBT is like an ad almost so you might have just scrolled past it. It’s right after my first paragraph but here it is again for reference:


I’ll post the schematic when I get done for sure, just to double check. When I get back on my computer tomorrow I can post my simple one line description of how the power is routed. Eventually I’ll want to get to each connection detail and ideally do a schematic like I have seen from other people.
All I see is an Amazon logo, that is not active as a link. If I edit the post, I can see the product code, copy that, and paste it into an Amazon search bar to see the product.

Edit: Looked at your post in Chrome, instead of Firefox, and there I get a product pic with a clickable link at the bottom of the pic. I think this is related to the recent upgrade of the HBT xenfro platform.

Brew on :mug:
 
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