Thanks, I am clear now on what is happening.
Inside the expansion valve controlled by that knob is a plunger and spring. There is a screw at the side designed to prevent you screwing it out too far and then water under pressure would exit the valve, as well as some hot water from the boiler once the pump is stopped.
The expansion valve is like this inside.
- A is the spring and pad which applies pressure to control the brew pressure. One end of the spring goes into a recess at the end of the knobs shaft.
- B 2 O rings to prevent leaking (these will require maintenance over time)
- C A rebate, this is to limit the movement open and closed of the expansion valve and to prevent you unscrewing it all the way
- D is the screw, that engages with C to limit the movement
The holder for the expansion valve is here, and you can see where screw D goes
You appear to be having problems opening it beyond the point where can can achieve less than 10 bar pressure, which isn’t right. Michael and I the owner of ECM did discuss some changes, but they were around some different issues and not this,
I am wondering is there is an issue with the spring sitting in the end of the valve properly…it may not be in that recess at the end of the stem correctly, if so, this would prevent you getting the pressure lower than 10.
A bit like this on the top drawing, instead of in the recess like the second one.
This is the screw in place and there is a little seal. I modified mine (which you must not do), so my screw does not engage in that rebate and I can actually screw the valve out of the front of the machine for lubrication and maintenance. To check your valve you will have to undo that Allen screw, remove the valve from the front. Then reassemble making sure the spring sits in the hole of the stem correctly and see if this fixes the problem.
Or go back to your retailer about the issue, unless you feel confident attempting this.
Please note: These images are from a prototype I had around 2 years ago!
I noticed you posted the same question on CFUK, I would appreciate you don’t repost this stuff on there, or Verticalscope will try and claim ownership of my information. Which I wouldn’t want monetised by them.