Originally Posted by CalypsoCowboy
Question on this build, I'm looking to do something similar. How well does the second batch of water come up to temperature. What I mean is as follows.
1. Heat up mash water, push it to the mash tun and dough in.
2. You now want to use your HERMS coil, so you add new water, normal tap water back to boil kettle enough to cover the HERMS coil, but that water has to come up to temp before it can be used for HERMS.
How long does step 2 take? I'm curious because if it takes 15-20 minutes, that's 1/4 to 1/3 of your mash time.
I'm trying to understand how well a 120V HERMS works.
Pretty close. I had a stock pot of extra water on the stove heating up while the kettle heated. Once the set point was reached I transferred the right volume to the cooler. Using the hot water from the stove I topped off the kettle to cover the coil and turned the PID back on to heat it up (it was pretty close and didn't take long). I know that is kind-of cheating, had I not used the stove, it probably would have added another 20-25 minutes. I would not add the grain before the kettle was ready for the recirculation.
Once the kettle and mash tun were at the same temperature, then I added the grain, fine tuned the flow and let it go. Perfectly stable the whole time.
Here is a photo of the heat exchange water in the kettle spinning away, and a shot of the recirculation fluid in the drop leg to the mash tun.
After 60 minutes, set the PID to 10C above mash-out temp to create a greater temperature gradient. I didn't record how long it took the mash to make the rise, but it wasn't memorably long. Once the mash got near temperature I lowered the kettle to actual mash-out. After 10 minutes, the element was turned off and the kettle was drained. A flip of the valve assembly and the fluid was pumped into the kettle. I used a little bit of the water from the kettle to sparge, mainly for a better fluid recovery than for sugar retrieval.
At 100% power the kettle had no problem boiling the 19.5L yielded (hair over 5 gal). After 60 minutes of boiling I lost exactly 3 liters.
I'm super happy with the performance. I'm not shattering any speed records, but when a large part of the brewday turns into "push button, walk away, and get perfect temperatures", I'm content to let it takes it time.
The cleanup process needs some optimization. My first strategy took way longer than it needed to. Lesson learned, hopefully better next time.
Let me know if you have any more questions!