as one of the folks who spent a lot of time on the phone in deep discussions about the development of the protocol, i'll throw in my $.02:another_jim wrote:However, if I were an HX manufacturer, I'd reject it and refuse to submit my machines to this test. They could justly claim that the inter-shot procedure is systematically biased in favor of dual boilers.
the protocol isn't biased for or against any machine or machine system. the objective presented for machine performance was stable, repeatable brew temperatures over a variety of duty cycles. the protocol reflects that objective. we knew the HX people might have kittens over this, and really went out of our way to make sure the protocol fairly measured machine performance. we also knew that the protocol would show the cold start of marzoccos. the duty cycle variation was specifically intended to show weaknesses in machine performance, for both types of machines. note the wbc/usbc competition schedule has a variable duty cycle: the competitor can use it as much as they like during setup, and then the machine sits for a few minutes (an unknowable period), and then it is put back in service at an unknowable duty cycle.
recall that it was precisely this phenomena which pushed me down the path of machine modification, and recall that the manufacturer denied any such problem existed.No matter what the HX design, the equilibrium shot temperature will depend on the shot making pace. If the pace is slow, the temperature over a long series will settle at a higher level than if the pace is fast. This has to be, since at the slower pace, the HX is heating up more. You are dumping the first four very slow measures for inter-shot calculations. But you still have the pace accelerating from 2 min 35 seconds to 45 seconds between shots. This will always cause the brew temperatures to drop for the later shots.
an easy fix, no doubt, except that no manufacturer specifies that any such flush is required during the routine operation of their machines. this harks back to coffeegeek's test procedure, which only follows "out of the box" performance, not how the machine performs after tweaks and surfs and other machinations which are not specified by the manufacturer in the operating instructions. if the manufacturers want to stand up and say, "yeah, our machines are only stable if you do x, y, and z," then x, y, and z may become part of the protocol.The easiest, and I think correct, fix is to allow each manufacturer to specify the amount for the preshot flushes.
in essence, you're suggesting the hx manufacturers be allowed a self-determined handicap because their machines won't perform even up to their own specifications and marketing. how about getting the manufacturers to make machines which will perform up to the desired specs? the goal was to find out how machines really perform, not how they perform after the barista spends ten years becoming intimate with the quirks and foibles of the machine. yeah, i can start my MGB w/o any problem, but valet attendants invariably cannot (it's that manual choke thing).