Puristika Hi everyone ! I think i have an issue with my new ECM Puristika (it’s my first time with E61)
The symptoms are classic for a thermosyphon stall. The brew system is sealed and heats the group by a continual flow of water. Water enters the group from high up in the boiler (or the top of the boiler.
In this photo of the prototype Puristika I got way back in Jan 2020 (almost 2 years ago, so it might be slightly different to yours inside), you can see the boiler with the thermosyphon pipes marked with Red and Blue arrows. The brew system is sealed and heats the group by a continual flow of water. Water enters the group from high up in the boiler (or the top of the boiler), red arrows. it then leaves the group by the smaller bottom pipe (blue arrows) and enters the bottom of the boiler to warm up again.
This continual circulation is what heats the group and keeps it warm…if for any reason, air gets into the sealed brew system and collects in the top of the boiler, this thermosyphon will stall (stop) . As soon as you run the pump the air comes out of the group and the thermosyphon restarts.
Symptoms are a cool group and if a shot is pulled without any portafilter in, a short delay (depending on how much ait gets in) before water starts flowing….the cool group with then suck heat away from the brew boiler as the thermosyphon flows and more water than you think comes into the boiler and depresses the brew temperature temporarily.
You can confirm this easily (unless the air leak is really bad…). When you start the machine in the morning….run the pump until you see water exit the group….then you will find it warms up properly
So you have had the background as to what and why….also how to confirm it…I guess the real question is; why is your machine doing it.
- Leaky top E61 brew valve
- Loose boiler connection leaking steam, or pipe from boiler leaking
- Leaky expansion valve. the little knob thing you can twiddle (make sure the brew pressure is set 7 bar plus.), preferably 8 or 9 bar
- Rotary pump machines have a 1 way valve and vibe pump machines usually rely on the vibe pump to prevent backflow. I am pretty sure they added a 1 way valve to puristika just in case (green arrow)
These are the only places air can come in, and o course water out…find that leak and you fix your problem. You next need to check with your retailer if they are happy for you to remove the case….let it warm up, look and listen for any leaking/hissing, or if your portafilter basket is always damp. Take a photo and put it on here for us to have a look at.
Now this next bit is important: There is no middle position for the lever that is meant to do anything, and you absolutely don’t want to use it with a single boiler machine like Puristika. This type of machine has no way of knowing if water is low in the boiler, plus it introduces air in the system, that stuff we were talking about. If one day you forget and leave it in the so called preinfusion (middle position), you stand an excellent chance of a failed heating element on your return, if you are gone long enough….and don’t for a second think the limit stats will always save the heating element….they most likely won’t. This is because it’s not water overtemperature, but the top of the heating element becoming exposed and going bang.
I look forward to hearing the result of your investigations.