Thermosyphon stall

Robert Hall

So, I have been using my L1 for a while now and making excellent espresso. When I pull multiple shots, I don't always pull some water through the grouphead after a shot. I have read that doing this will prevent thermosyphon stall (and also clean the screen). How would you know if you have had thermosyphon stall....what are the symptoms? Don't think I have had it. I presume the water stops flowing to the group and the group cools down, but not sure.
Rob

Reiss Gunson

the new high performance piston seals *appear* to have eliminated the need to flush after a shot to ensure the TS keeps rolling, but it is standard practice on any espresso machine (pump or lever) to make a short flush after each shot to rinse the screen & group, so you probably haven't experienced it

with the original seals supplied by the group maker if you did not do a post shot flush the group temperature could drop down and the next shot would taste sour (extraction temperature too low)

i think a short flush after a shot represents best practice on any machine for most baristas

Rocky Strickland

After the recommended 55ml flush, how long should I wait before pulling the next shot?

Rocky

Reiss Gunson

No waiting required

Set to work preparing the next shot immediately

Frans Goddijn

If there's more espresso to brew, I just go on and on. The brief flush just needs to make the "psht" sound you will notice and then all is well in the TS.

Robert Hall

I typically don't wait long and am getting good results. If I remember to flush, I will go through my grinding and tamping routine which takes a few minutes, and pull the next shot.
I'm still not 100% clear on this stall thing....does the group cool down significantly? If you were to put your hand on the group would it be noticeable?
Rob

Frans Goddijn

With your hand you would not notice. The hot water flowing in temporarily heats up the group (which is useful because it cools down the water a little so your coffee is not too hot) and at the same time while you pull the shot the TS is temporarily closed and not heating up. That balances each other. Then after the shot you do the quick release of a little splash and TS is active again while you grind and tamp...

Reiss Gunson

That's probably because you've got the new HP seals fitted - they seem to alleviate the issue

With the original seals if a post shot flush was not made the next shot pulled could be pale and sour, a result of underextraction from brew water that was too cool

Kind regards

Reiss

Robert Hall

Reiss,
Got it!! So far I don't think I've ever had that problem. The machine keeps cranking out great espresso. I think the L1 is a step up from my previous GS3.
Rob

James Springfield

I still get the stall with the new seals installed unfortunately

Jack Blackmore

it's happen to me a few times as well with the new seals but since I've started using a short half second flush between shots and more importantly after the last shot it's not happened since.

Reiss Gunson

but it doesnt occur on the LONDINIUM R.