fwiw, when I was putting my 3v 20g herms kettles together I made sure to mount the hex in the hlt as low as I could and still clear things like the valves. Also, I kept the coil "barely spaced", just a scant gap between loops. All that to require the least amount of water to cover the hex. In my case I need 9.5 gallons to fully immerse the hex, which is just about the typical sparge volume I need for my 10 gallon batches.
More water than the minimum needed means longer time to heat which means steps take longer and more energy used...
Cheers!
The total volume in the HLT is something that I recently have given some additional thought and consideration. I went from propane fired to electric 6 or so years ago. It was something of a stumbling into decision after finding an unfinished panel for sale. Often many of my builds are like that-a "bargain" component shows up and I jump into the project. I ended up chasing down the booklet for the panel, but it was bare bones and I didn't have a lot of experience assembling an electric system. I only had one pump at the time and hadn't done much to incorporate it even. The HLT with the hex was totally a new component to me and I was more focused on not electrocuting myself.
Since building, I've brewed about 85-90% of the time six gallon batches, the remainder 10 gallons. I've always had excess water. I tried to minimize that by working to just keep the coil covered and using the excess heated water for cleaning the MT. But on a keggle, port placement is affected by the wall shape (ribs) and bottom curvature. Also, the element in my case needed an outside electric box, which needed water tightness. Anyway, I hadn't really given too much consideration too minimizing the total volume in HLT build, mainly just getting it work and to use less water by just keeping the coils submerged.
Operationally in my system I was aware of the excess heated water resulting from my EHERMS. I can use either A.Heat the strike water directly in the HLT, then remove and add to the MT or B.Indirectly heat tge strike water in the MT and heat by recirculation through the hex. Pros and cons to either relating to MT issues but both result in the bulk of the remaining HLT water being in the mid 160s (F, single step infusion). If using A, at a minimum several gallons of strike water need removal (6 gallon batch). My coil's top is at about 10 gallons (stair use currently limited and not checking exactly). I can start with the HLT full and then add cool water to drop the HLT temp down to mashing temp. It's a bit of a jerky/oscillating process based on batch size and recipe mash temp. It requires a full HLT to start or at least recipe dependent additional calculations. I typically use B, which requires a total volume that covers the coil. However, after the grain goes in, about one to no more than two additional gallons need adding to get the HLT back to mash temp. Those amounts ilkustrate why A is jerky. Ten gallon batches using A drain way more water, which needs more heat and time to bring the temp back up while the grist will need recirculation. B is smoother but leaves an excess 1-2 gallons of water in the HLT that needs additional heat and time to change temperature for remainder of the mash as
@day_trippr more succintly mentioned.
Solution 1. The excess water from B could be removed after stabilizing the HLT at the desired mash temp as the easiest solution. I hadn't considered it that much of an issue as I was using the water to clean. It would also require turning off the water pump and partially removing the hoses. (It's helpful to recirculate within the HLT.) It's still wasted heat energy if not used immediately and wasted water if poured out.
Solution 2. This one is very much dependent on my own brewhouse. Use my glycol chiller to drop the HLT temp. This requires a separate hex in the HLT. I've been hunting for a small cheap SS coil to fit into the middle of my HERMS coil. It takes at least 5 and maybe more even minutes for the grist temp to stabilize. I recently purchased two Auber320s to replace the HLT PID and the BK power regulator in my panel. There's a relay function on the Auber that could drive the pump in the glycol chiller. In fact the Auber can drive two such functions with appropriate electrical components. I tabled this idea but one of the two relays can be used to program my water pump. (I have separate plans for the relay functions on the BK Auber.)
Solution 3. Heat the strike water separately. Not possible within the confines of my 30 amp panel. However, I am currently in the middle of a build for a pico-pilot electric BK for 3 gallon batches. It uses an Inkbird IPB-16S and runs on 120V. I have a spare pump for it. It occurred to me that I could heat the strike water in that. One could simply heat the strike water on the stove or a gas burner too. This is faster than Solution 1 because here the 220V element is only heating the minimum amount of water in the HLT and the strike water is heated by 120V. It's only a 6 gallon kettle though. Probably not enough for some/many(?) 10 gallon batches. Personally I might need to mix Solutions 1 & 3 for large batches.
Sounds like
@Shwagger you may already have considered some of this and I'm sure there are other ideas out there too. I've noticed some of the AIO offerings have separate add-on electric kettles for sparge water but I don't know much about them. I was already building my pico-pilot e-kettle. I got the kettle, Inkbird, element and pipe stand at about 50% off plus had the spare pump after an upgrade so it's a "bargain" build. I could have maybe went with a cheap AIO to small batch brew or heat strike water even. I like building stuff too though.
