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Posts uit juli, 2013 weergeven

Cold TS pipe ahead of 'hot' one until flush & switch

Afbeelding
Caught a clear example of a very logical TS flow direction switch on the L1. The pipe that's designed to be the cooler one of the two is physically, when connecting to the brew group, lower and thus closer to the boiler. At warmup in the morning, it therefore heats up a tiny bit quicker than the upper pipe and for a few minutes it takes the lead with a flow from the lower pipe into the group and out of it through the upper pipe back into the heat exchanger. During a short 200ml open port flush at minute 10, the upper pipe heats more from water flowing out of the HX pipe going through the boiler, the lower pipe cools a bit and then they both are at the ideal start position for the regular flow, heating up the brew group further. Scace sitting next to the machine at 28ÂșC ambient temp.

Stiff shot straight from the trailer

Afbeelding
Here's another phenomenon which may be observed in some users' Londinium I machines when they do measurements and see a dip in group temp. For quite a while I've been convinced there must have been air in the TS then, by pushback or any other way like insufficient greasing or just taking apart the hot group to check the lube situation. A flush of a 'nut bleed' helps get rid of air and when this indeed helped cure the 'dip', I assumed my assumption was right. Over time I've noticed a different pattern though. My machine, when idling an extended time, can tend to 'dip' in group temp if I pull a shot and then do nothing. There's a certain stiffness in the system. The flow of the TS is there but as everything was hot enough, rather than overheat, the TS slowed down more and more and after the pull it needs some time to speed up again. Any of 3 possible solutions work here: 1) pull another one 2) do a short flush (as if you need to quic

TS reversal, group fine, espresso delicious

Afbeelding
The Thermosiphon pipes of my Londinium I sometimes (when an espresso is made, or a flush done, effectively closing the pipe communication and letting them start over) reverse their roles, one heating the group, the other brining back the somewhat colder water towards the heat exchanger inside the boiler. I find it interesting that it's able to do that and be just as effective. On second thought, it's not really a miracle. If you place a kid on a swing and give it a push, it doesn't really matter which way you call "forward" or "backward."  And every time you take the kid off the swing and ask it to climb back on for the next push, it doesn't matter if it faces you or not. The espresso was great anyway. I also took some measurements using a so called 'SCACE device', basically a standardized plastic 'puck' replacing the coffee grinds and a restrictor for the hot water to flow out more or less at the speed and dose of a 're