I have a Herms. I dont continually circulate during mashing. Kegs with insulation/lag dont lose anything measurable. I just use the herms to ramp up to the next temp. It'll bypass the HEX when the mash temp is spot on. Then I turn it off for the time resting at that temp. Basically its a massive vorlouf to get up to temp, with no spike in temp (i.e. 90c water dump). That with underletting makes for extremely clear wort.Herms = Heat exchange recirculating mash system
Rims = Recirculating infusion mash system
The idea is to keep wort flowing and circulating through the grain bed during mashing to keep it at a preset temperature.
Herms uses a heat exchange unit to "smooth out" the heating
With Rims the wort passes directly over/around a heating element.
All use pumps. The size of your manhood is directly proportional to the number of pumps in your brewhouse
Braumeister is also a RIMS system, technically speaking.
Edit: off to do a BIAB American Wheat, just measure some grain temperature etc first, then I'll do my exact process to knock out a totally repeatable wort as I always do with this style