R.I.M.S. stands for "recirculated infusion mash system" and involves in-line heating of the wort from the mash tun during the mash. My setup uses a 6 metre copper pipe coiled (vertically) within the hot liquor tank. To get an increase in mash temperature during the mash I simply pump the wort through as shown above and, assuming that the hot liquor tank is 20°C higher than what I want the mash to stop at, I can heat all 54 litres of mash by about 1°C per minute. I estimated that the wort takes around 10 seconds to go through the hot liquor tank and so the enzymes should be safe. I haven't experienced extraction problems so far and so assume all is working to plan !
For mash out you can set the hot liquor tank temperature to say 90°C, do the step up and then remove the excess heat from the hot liquor tank by quickly running cold tap water through the same coil. Hence you can quickly return to sparge temperature.
