I just finished brewing Thunderstruck Pumpkin Ale with my electric HERMS and thought I'd offer some tips. This is my third time brewing this recipe but my first on an electric HERMS. Before, I was using a three-kettle, direct heat, and pump-fed system to brew this recipe and I suffered from stuck sparges and clogged pumps. Today's brew went off with out a hitch! Here's how...
I use an electric HERMS that's operated with two pumps and a HERMS coil in the HLT. I use a silicone tube inside my MLT (Sabco-style) for re-circ and I allow my mash to re-circ through the coil for entire mash. I wanted to accomplish this today without getting clogs and I did!
I added 1.25lb of rice hulls to the recipe and made sure to mix them well with the other grains and wheat. I mashed-in with the grains to hit the 158-deg mash temp. Then, I took my room temp Libby's pumpkin (which was already baked for 30-min at 350-deg) and placed it in a 1-gal paint strainer/bag and laid that flat across the top of the grain bed. My re-circ tubing was relatively close to the pumpkin/bag.
That's it! I mashed for 60-min with constant re-circ and then fly-sparged for about 45-minutes to collect my wort. The pumpkin color/flavor was extracted nicely, my efficiency was normal (75%), and the pumpkin stayed collected in the paint strainer. I hope this helps anyone who might be considering this recipe for their HERMS.