HERMS Build

I attached a photo of the HERMs system I just built. I tried to wrap the 15 gallon kettles with wrap insulation. Unfortunately the bottom 2 to 3 inches burned away. Anyone know of better insulation for this use? Also, I have to maintain the HWT about 4 degrees warmer than the mash temp to keep the mash temp from dropping. Is that typical? I don't want to have to heat the sparge water to 172 to mash out at 168 as the sparge will be too hot.

From reading, but not from experience, several degrees warmer for the HLT to keep your mash (depending on where you take your temperature) is typical for a HERMS setup. When you are ready to sparge, it won't take long for it to drop to 170 or so. So no worry about sparging too hot (assuming that 172 is going to raise the mash to the heat level to kill enzymes by the time you kill the heat at the end of the mash).

/run a RIMS system so I'm only of marginal assistance. But I investigated HERMS pretty thoroughly before building my system.

thanks.

i am going to install an inline thermometer at the outlet to see what temp is coming out after the heat exchanger. If the heat exchange becomes a nuisance, I may just use a bypass line and make it a RIMS system. Heating the entire lot is more efficient than about 3-4 foot length of small copper pipe in the HWT.