I never meant to imply that HERMS scorches. I was saying, "like a HERMS, there is no possibility of scorching" or "there is no possibility of scorching, just as in the standard HERMS design."
I think it is pretty likely, though, that you are going to have more even heat transfer with this system. It is distributing heat to multiple layers of the mash, so there are no issues with stratification. And then the water is also recirculating. That has to produce more even temps than depositing pre-heated wort at the top of the mash and relying on recirculation to transfer that heat throughout the mash.
Regarding the residual heat from the coil, at the point that the pump stops, a good portion of that heat will already be transferred to the mash. The water in the coil would have already transferred some of its heat. The water in the coil will still be hotter than the mash, but would this really have a significant impact on the overall mash temperature? If it was enough to even raise the mash temp a half-degree, then it follows that we would have to recirculate only for a couple seconds in order to raise the mash temp back to its setpoint. Clearly this is not the case. The thermal mass of the heat exchanger is small relative to the mash itself. So residual heat would not be significant.
This has been re-hashed here many times.
Any links to previous threads? This is what I was trying to find out.
Ok, perhaps the JC A419 does not require an SSR for a 1500 watt element. My RANCO does. And if you are trying to control any SIGNIFICANT amount of heating, you are typically going to need an SSR. A 1500 Watt element would be the bare minimum that most people would be using for a RIMS or HERMS.
The only additional equipment required for this system is an extra pump and relatively small pot, as opposed to, say, a solenoid valve, ssr, rims heating chamber, or whatever you are using for a typical RIMS/HERMS. The heat exchanger coil can be added after dough-in and then later reused as an immersion chiller. So if you already have an immersion chiller, you could use it for this application.
Also, to clarify, it does require 4 vessels, but not 4 burners. The boil kettle just scoots over and uses the burner that was used for the hot water heater. You are not going to be using the boil kettle while recirculating.
I didn't know about cavitation with boiling water, never tried to pump it before, so that's good to know. I would have to keep the hot water heater just below boiling. That shoud be feasible by adjusting the flame to the right output. Whether the water temp it is at 190 or 200 doesn't really matter, considering that I am just using the heat exchanger to add small amounts of heat to make up for whatever it lost during recirculation.
Anyway, since it is so simple to implement and I already have the equipment on hand, I'm going to build it and test it, as that really seems like the best way to evaluate the system. Obviously there could be an extended argument about the benefits and disadvantages of each system. There are several issues I have encountered with the standard design, and this is an attempt to avoid those issues.