Hello,

I just noticed how much the expansion valve drips while at idle, and flows during a shot. Is this normal? I never noticed on any of my other machines. I have adjusting the valve to remain in the 9 BAR area while pulling a shot. My shots are still not where they were with my mini, but that takes practice.

Thanks

Felix

Use the bypass valve on the pump to adjust the brew pressure.
I have my expansion valve set at just under 12 bar.

Thanks Jacob. Your gauge is at 12 while pulling a shot? I thought optimal is somewhere near 9. Wondering why my shots look great but taste bitter even with fresh coffee and correct temp.

Nope, I pull my shot at around 9 BAR (adjusted by the bypass valve on the pump).

You may be confusing two separate adjustable pressures. The expansion valve protects the brew boiler from acheiving pressures above 12 bar when set correctly. This has nothing to do with brew pressures. Brew pressures are set at the pump. The pressure you read during brewing should be 9 bar. After cold water enters the boiler, the water is heated and pressure in the boiler may rise (this is usually following a shot). If the pressure tries to exceed 12 bar (the expansion valve setting), the expansion valve will bleed off some water to prevent the pressure from rising any further.

You can see how to adjust the two valves on page 7 in the manual

Thank for the response. When I first started using the machine I had to tighten the expansion valve because water was flow from it at a rapid pace. I will try adjusting ASAP. How much of an increment am I looking for?

I've read the best way to set the expansion valve is to cool the machine overnight (turn off) then when you turn it on and the boiler heats up, you should notice the pressure rise. You want to keep this under 12 bar using the expansion valve. For me, I just the pump without the pf in place for 30 seconds and then watched the pressure gauge as the boiler recovered.

felixnyc wrote:Thank for the response. When I first started using the machine I had to tighten the expansion valve because water was flow from it at a rapid pace. I will try adjusting ASAP. How much of an increment am I looking for?

Sounds like the expansion valve was left open after draining the brew boiler following the final bench test.

To adjust the expansion valve:

1. Turn off the machine and let it cool.

2. Remove the right side-panel. You do so by unscrewing the two round silver decorative nuts. Do that by hand if you can. If not, wrap a pair of pliers with electrical tape and use it to gently unscrew the nuts (if you don't use tape you'll scratch the plating off the nuts.) Then you'll need a metric socket to unscrew the safety nuts that are under the decorative nuts. I believe they take a 13mm socket.

3. After removing the right side-panel, you will be able to see the expansion valve and observe it's setting (how far up the movable part is screwed.) As the manual shows, the expansion valve is above the extreme right-rear of the drip tray.

4. Screw the expansion valve all the way in until it just seats at the end of travel (don't tighten it, just screw it down until no more threads show.) You may be able to do this by hand. If not, use the wrench wrapped with tape from step 2 to turn the bottom of the expansion valve (the part that sticks down into the drain tray.) Note that you'll need to turn the expansion valve from the drain tray with pliers to adjust it after the boiler heats up.

5. If you see vertical marks on the fixed and movable parts of the expansion valve, unscrew the expansion valve until the marks line up. The marks, if present, were put there by the manufacturer or dealer to show the correct initial setting of the expansion valve. If the marks are not present, unscrew the expansion valve one full turn.

6. Turn on the machine and let it start heating up.

7. DO NOT ACTIVATE THE BREW PUMP IN STEPS 8-10:

8. As the boiler heats, if you see any water coming out of the expansion valve while the brew pressure indicates less than 12 bar, screw in the expansion valve until the water stops.

9. As the boiler heats up, if the brew pressure gets above 12 bar, unscrew the expansion valve until the pressure drops below 12 bar. Do not let the brew pressure exceed 12 bar.

10. When the boiler reaches the target brew temperature, make sure the pressure is less than 12 bar, as in step 9.

11. Turn on the brew pump for a few seconds. If you have adjusted the bypass valve on the pump correctly, the brew pressure gauge will read exactly 9 BAR. If not, refer to the manual for adjusting the bypass valve. This involves removing the left side-panel, in the same manner as you removed the right side panel. The bypass valve is on the right side of the pump, below the stainless output hose. Loosen the lock nut on the bypass valve and adjust the screw until the brew pressure reads 9 bars with the pump running. Tighten the lock nut. Tightening the lock nut may change the brew pressure, so run the pump to check it again. You may have to loosen the nut and adjust the screw several times to get it right after the nut is tightened.

12. Once you have the brew pressure adjusted correctly, run the pump for about 25 seconds and turn it off. The brew pressure will then increase rapidly as the boiler reheats. It should reach a peak of 12 BARS. If it doesn't get to 12 bars, tighten the expansion valve about 1/8-1/4 turn. Use the pliers to turn the bottom of the expansion valve from the drip tray. If it goes over 12 BAR, unscrew the expansion valve by 1/8-1/4 turn. Then run the pump for 25 seconds again and check the peak pressure. Keep running the pump for 25 seconds and adjusting the expansion valve so that the pressure hits 12 BAR consistently at the peak. When it does, marks the fixed and movable parts of the expansion valve with a Sharpie to mark the position of the expansion valve. In the future, if you drain the boiler through the expansion valve, you'll be able to set the expansion valve back to the marked position and be pretty close to the correct setting.

13. Check the brew pressure several times over the next few hours and/or days. You'll probably need to make minor tweaks to it so that the brew pressure hits 12 BARS after each reheating cycle. You can re-mark the expansion valve if you like. I don't -- I just set it to the mark put there in step 12 and fine tune it over a period of several days.

Hope this helps. If you have any questions, just ask.