Hey guys,

I asked that question in one of the Appartamento threads, but didn't get an answer. I think it could be an overall E61 thing, so I post a new topic.

I have an issue with my appartamento that really bothers me, because I can't find the reason for month now. I use a thermometer similar to Erics. After performing a short flush (up to around 5 seconds), per example for cleaning the shower screen, the idle temperature of my machine drops from 205° to around 195°or even much lower and would stay there forever until I pull a espresso shot, backflush or perform a very long flush. I think that could be a TS Stall. I found very little information about it and I simply can't imagine, that everybody with my machine has that problem. I would be very happy to have it solved.

My dealer and workshop wasn't able to find the reason, it took me the first hour to make them believe me though...
I am (was) in e-mail contact with Rocket as well (Andrew Meo himself), they didn't believe me at first, too and explained me all other temperature related stuff I allready knew, but didn't seem to understand my problem. I made some youtube videos, explanations and graphs for them but didn't get any answer since then and I don't know if I ever will.

Here is the related video (#2 out of 3) that shows the temperature drop after a short flush. I did some talking in the beginning (originally for Rocket) You can scroll through it after the flush since it is in real time and that would be pretty boring...
Does anyone has any idea if that problem is normal and unavoidable or is there anything wrong with my machine which leads to that issue, that could be solved?

I am thinking there is a leak. Have you tried installing the blank disk in the portafilter and putting the portafilter back into the group after the quick flush to see if the temperature drops? If the temperature no longer drops, then for sure there is a leak. The gaskets then need to be replaced.

Also make sure you have the right gasket/fitting installed for the thermometer to prevent leaking there also.

That is indeed a thermosiphon stall and I don't think that's an acceptable behavior (would be an engineering/design failure which I don't expect coming from Rocket).

Not sure why a short flush would cause the TS stall in your case though. As suggested, leaking somewhere in the system could lead to this. Do you observe any leak from the OPV after the short flush? If it is ok to do so (check with your dealer), you could open the hood to observe if there is any oddity.

Thank you for your replies!

athoangphan wrote:I am thinking there is a leak. Have you tried installing the blank disk in the portafilter and putting the portafilter back into the group after the quick flush to see if the temperature drops? If the temperature no longer drops, then for sure there is a leak. The gaskets then need to be replaced.

Also make sure you have the right gasket/fitting installed for the thermometer to prevent leaking there also.

I think everything is worth a try, but I do not really understand the point in putting the blind basket in after the flush. In my understanding, that won't seal anything, that could be leaky since the lower outlet pipe of the E61 is open anyway after the flush. The TS should be separated after the flush by the upper valve of the brew group, it shouldn't matter what comes "behind" that like the thermometer, or am I wrong? If the upper valve would be leaky, a correct sealed thermometer and a sealed shower screen by the blind basket wouldn't seal the system, since the exhaust valve is open.
I tried it anyway, because I might be wrong, but the outcome was the same.

But you gave me the idea to try to backflush very short (2sec) to see if the TS Stall occurs then as well and isolate the problem a bit more. The result is that everything goes fine afterwards. So to trigger the TS Stall, I need 3 things:

- Short time (somewhere less then 5sec)
- No counterpressure (blind basket test)
- A heated up machine (I can't trigger the TS Stall when I flush a cold machine. It will heat up normally afterwards)

samuellaw178 wrote:Not sure why a short flush would cause the TS stall in your case though. As suggested, leaking somewhere in the system could lead to this. Do you observe any leak from the OPV after the short flush? If it is ok to do so (check with your dealer), you could open the hood to observe if there is any oddity.

The OPV is a good idea, because I read a few times, that it could be leaky on low pressures. I opened the case and couldn't see any leakage.

I found that picture here in the forum to explain two things:
The only thing I recognized are some air bubbles coming form the vibration pump towards the reservoir in that hose just left of the red circle while flushing.
When backflushing there are a few air bubbles coming up in the reservoir as soon as there is pressure in the system.
Are those two things normal?

Maybe a weak vibration pump could be a factor in triggering the TS Stall I thougt. Could anyone measure how much water comes out of the group head in a 10sec flush with a heated through machine (if mine is cold, first 1-2 seconds no water comes out)?