Guys, by the way, Chris Colby wrote an article in BYO a few years back (the ABCs of brewing systems issue) that described a HERMS as switching a valve that controlled wort flow. He said that the mash temperature was controlled by either recirculating the wort back to the mash tun, or recirculating it through the heat exchanger to the mash tun. He said that the temperature of the heat exchanger stayed constant, the recirculation was constant, and the only variable was whether the wort travelled through the heat exchanger. That seems like an odd approach to me, though. It seems like it would be easier to automate an electric heating element than a valve.