HERMS Hex question

You guys that recirc your wort through an HLT heat exchanger,

1) what temp do you keep the HLT water at? Boiling?

2) what happens to the wort in the hex tubing when your recirc stops (the pump is turned off because the mash is at temp). Doesn't it increase to the temp of the HLT water? Is this an issue when the pump comes back on and returns it to the mash?

I assume none of this is a problem because you all are doing it... just wondering. Thanks. I'm rapidly building mine right now.

 

I had some of the same questions because I am moving from RIMS to HERMS. My plan was to place the HERMS HLT above the MLT and push the mash liquid to the drop of the herms coil to allow it to drain back into the MLT by itself after the pump stops.

 

You must control the HLT water temp. It is usually a degree or two higher than mash temp. The pump runs continuously.

 

I'm in the process of putting mine together. My plan was to run my sparge water through the copper coil after the wort. Not sure if that would work on your setup, mine is a two tier with the HLT and MLT on the same level using the pump to sparge.

 

I think the HERMS user community is split between having the controller cycle the pump on and off and those who continue to circulate.

 

Although I hadn't previously considered it, cycling the heat to the HLT makes sense. I worry about the control loop (where to put the temp probe) and oscillations. Got to get the hysteresis right.

I have build an electric HLT, so controlling the temp there is easy.

 

I have never seen a HERMS that controls the pump instead of the HLT water temp.

Control the HLT temp. In my system the differential between the HLT and the MLT target temp. is about 3F. When I say about, I mean I have been within .5F of target temp on the past 9 brews. My temp. probe is in my HLT, not in the wort flow.

HERMS is easy... it is reliable and it utilizes the HLT and the water that you have heated already.

I use my HERMS HEX to mashout, so that HLT water is now at 173F, perfect for sparging.

I also NOW use my HLT and HERMS HEX to COOL the wort. I use a closed system cooling process that consists of ice and water in the HLT to cool my wort after the boil to 66F in 20 minutes, 57F in 25 minutes for lagers.

I will be brewing on mine on 10-27-09. I will be doing a brewcast, there is a thread on here if you would like to watch and see it work.

 

That all makes great sense. Thanks for saving me from doing the stupid thing. Sounds so obvious now... ugh.

 

Meh, no problem. I find the the simplest solution, is generally the best. Good luck on your build.