Slow Mash Temperature Rise with Stout HERMS System
I'm using a Stout brewing system where wort recirculates around the outside of the HLT to heat the mash.
I'm having trouble raising the mash temperature from 65°C to 75°C.
HLT temperature: 83°C
Wort returning to the mash tun: 78°C
After 90 minutes of recirculation, the mash only reached 72°C.
My questions:
Is it a problem to recirculate the mash for over an hour at these temperatures?
Is there a risk of increased tannin extraction or astringency?
For those using a similar HERMS system, what HLT temperature do you use, and how long does it typically take to raise the mash temperature by 10°C?
I'd appreciate hearing about your experience.