Phaedrus wrote:Thank you Paolo, the Achille is certainly the less expensive choice (assuming I can still get it) and has local support. Were the shots not up to par when you had the original dual spring setup (12 I imagine)? I'm not sure I want to mess with springs on a brand new machine, but that seems secondary to the TS stall you mentioned. Is it simply a matter of flushing after a shot to avoid the stall? I would imagine the flush would be done after a shot to clear the screen anyway, so when you refer to "no drama" is that what you mean? I certainly want to avoid any machine that will bring any drama to my household. In my Italian household, there's no capacity for any more Italian divas!!

Thr Londinium also needs a short flush after pulling a shot in order to avoid TS stall. (But, as you say, this also cleans tne shower screen.) At least this is the case with the pre-R L1s.

Please excuse my ignorance. What is 'TS Stall'?

Thermosyphon stall

Paolo, do you or any other Achille owners know how the group is fed? E.g. The Londinium R is a "cold fed" HX thermosiphon design, the Pro 800 is a dipper. What type of machine is the Achille? I can't seem to find anything anywhere.

mathof wrote:Thr Londinium also needs a short flush after pulling a shot in order to avoid TS stall. (But, as you say, this also cleans tne shower screen.) At least this is the case with the pre-R L1s.

I have not experienced a thermosyphon stall with my Londinium R without flushing post shot.. Either in practice or in testing with continous shots 3min apart with my scace device

Yea not an issue with the LR, although a short flush post shot to clean the screen is always useful.

Phaedrus wrote:Paolo, do you or any other Achille owners know how the group is fed? E.g. The Londinium R is a "cold fed" HX thermosiphon design, the Pro 800 is a dipper. What type of machine is the Achille? I can't seem to find anything anywhere.

Have a look at entry #20 here:-
https://coffeesnobs.com.au/brewing-equi ... hille.html


(Internal piping in Achille boiler)

grog wrote:Thermosyphon stall

Again, pardon my ignorance, is this caused by a loss of temperature differential between input and output at the group head to and from the boiler?

TNX

It's generally caused by an air bubble. The "syphon" part of thermosyphon requires that the entire circuit be filled otherwise the hot water floats to the top of the hot TS pipe and can't make it down to the group to heat it; hence the "stall". In order for the circuit to work, the hot water cools a bit in the group and then sinks down to the bottom of the boiler through the cool TS pipe. The falling cooler water then pulls hot water from the top of the water level in the boiler and the cycle continues.
Until an air bubble screws everything up.
A quick flush after pulling a shot is recommended to purge any potentially entrained air out of the circuit and ensure a happy and hot group on machines employing a TS.


Cheers!

- Jake

Thanks Jake!