Temperature stability

The consistency of brew water temperature during a shot, between back-to-back shots, and across a busy session. Stable temperature means the same beans, dose, and grind produce the same flavour every time.

Why it matters — Most "this shot tastes off" mysteries trace back to temperature drift. Unstable temperature is why some pulls are great and others — same grind, same dose, same machine — taste sour or muddy.

Good to know

• The two big upgrades for stability are a saturated group head and an accurate PID — both common on better prosumer and commercial machines.
• HX machines need a cooling flush after sitting idle, otherwise the first shot pulls hotter than the rest.