Hi, all. My Lelit Elizabeth v3 is around 3 months old now, and has started to behave a little strangely with regard to pressure. If I put in the blind basket, then engage the pump (no preinfusion, and it's been an hour or so since last use), the pressure spikes up to around 11 bar, then drops quickly to around 10 and holds. If I then do this again very soon after the first time, the pressure will only go to maybe 9.5 bars and hold. Then on the third such run, and all subsequent runs in this sequence, it will just go to 9 and hold there. Something very similar happens with coffee in the portafilter, though the pressures there decline during the shot as expected. I have found on other message boards that a few others have also had this problem, but I haven't really found any solution. One person suggested adjusting the OPV, which I had already done long before this issue arose to set it to 9 from the factory default of 10. I did adjust it again just to see, and it did not seem to help. In fact, when I adjusted it I set it to around 8.5 bars (as the pressure it gives after several runs in a row with the blind basket at least), but the next day it was back to its previous level and behavior, as if the OPV adjustment had undone itself. Is this a case of a bad OPV? How difficult is it to change out the OPV entirely?

> @"Pygmalion"#p1227 Is this a case of a bad OPV? How difficult is it to change out the OPV entirely? it's not difficult, but it's very unlikely that the expansion valve (OPV) has gone bad. If it had you would probably be getting other sumptoms. For the OPV to cause the behaviour you're describing, it would have to be stiffer and open later for the first shot, then open a bit further when the pressure drops to 10 bar. Then as you do more shots…it is loosening up. That' not really normal behaviour for that type of valve. If it was sticky, then usually it would jam up on other shots, possibly randomly…it's also very hard for it to stick. As you can see, the only bit that moves is the pad, held by the spring against the port. There is not much to stick or jam. The only par that could is the relatively loose fitting metal bit with a pad. [URL=https://i.imgur.com/fX9CLwu.png][IMG]https://i.imgur.com/fX9CLwu.png[/IMG] From your description, the behaviour seems to follow a consistent pattern, which would indicate another cause. I'm just not sure what at the moment?

@"DavecUK"#p1229 Thanks for the detailed reply DavecUK (BTW, I'm using your advanced parameters for the Elizabeth; thanks!). I wonder what could cause an issue like this, then? Could it be a temperature thing? That is, the first shot might be hotter (if I haven't done a purge, which I often don't), then subsequent ones in somewhat rapid succession are a little cooler, etc. Would this make the pressure behave in this way? My understanding of the OPV is that it sets an upper limit on the pressure, and that it should never rise above this if the OPV is working correctly. Of course, that's only the pressure at the OPV itself, which is not directly what the pressure gauge is reading (pump pressure?). So, if the OPV is not the problem, then it could be the gauge I guess, or it could be that somehow the pressure in the system where the gauge is reading is higher than the OPV in some strange, consistent-ish way. Anyone else having similar behavior?

@"Pygmalion"#p1238 In a rotary pumped machine, odd things can happen because the water goes into a sealed system through a 1 way valve. The expansion valve in that sealed system is set to 12 to 14 bar. In your system it's the expansion valve as you correctly say controlling the pressure, so there is an upper limit….not really sure…am cogitatingt. I even though perhaps air in the capillary tube, but that wouldn't case the problem you're getting.

Morning all, I noticed this morning that I have the exact same thing happen! Preheated for about 40 mins, purged for 3-5 seconds out of the hot water tap, waited a minute or 2, puled a shot with a 10 second preinfusion at 2 bar, after the 10 seconds it shot up to 10-10.5 bar before dropping back to 8.5. Subsequent shots only reached 8.5 bar after PI (I did another 2, one for my wife, the other for 'science', aka my second double before 0700 what could go wrong). The strange thing is, the timings were all exaclty the same, 16g in, 33 out in 33 seconds. I'm wondering if it's more of an issue with the display then with the valve? I've possibly got some friends coming over tomorrow for a pre/post run brew so if I do more then 3 shots I'll pay close attention to the needle and report back...

I've thought about what might be happening by imagineering how I this could be created if one wanted to do so. and looking at the way the Elizabeths were made (factory photos of first production run…I can't see how it can happen, or be made to happen, unless i'm missing something. The repositioning of the expansion valve is still within the sealed brew area, and they changed it for a much better and reachable/adjustable valve. The V2 I had which I modified to a V3 still; has the old valve, as you can see from my review photos, and hydraulically is in essentially the same position (if not physically) https://coffeeequipmentreviews.wordpress.com/2020/05/08/lelit-elizabeth/ So here is the image, just to orient people 1. Expansion valve controlling brew pressure max 2. Manometer take-off for pressure gauge 3. Autofill solenoid for steam boiler, opens to fill steam boiler 4. Exit port from ring group to vent solenoid 5. Vent solenoid, opens at end of shot. As you can see 1, 2 and 4 , all form part of the sealed brew circuit. The expansion valve is directly connected to the boiler, whatever pressure is experienced by the coffee, the same pressure is seen by 1, 2 and 4. The other numbered components take no part in this. The component under the autofill solenoid (3) is what does the steam preinfusion and incidently takes part in the clever way the machine does hot water. This component can't have any impact as it still only feeds into the same sealed brew circuit controlled by the expansion valve. This means any thermal expansion of water would be controlled ultimately by the expansion valve. My only possible conclusion is perhaps a shock wave caused by any slight airspace and water hammer due to closing of valves? **Perhaps someone could try switching of bloom phase and steam preinfusion, just have a straight shot…then see if it happens** [upl-image-preview url=//i.imgur.com/B9miMjc.jpeg]

Do you mean turn off the steam boiler or just not have any preinfusion? If so I got it just now with just a stright shot, no 10 second bloom, just 8.5 bars. It still spiked up to about 10 bars and the second shot rose to 8.5 and stopped.

> @"Del_UK"#p1323 Do you mean turn off the steam boiler or just not have any preinfusion? If so I got it just now with just a stright shot, no 10 second bloom, just 8.5 bars. It still spiked up to about 10 bars and the second shot rose to 8.5 and stopped. Everything off, probably even steam boiler (even though it shouldn't matter)…but certainly both preinfusion functions (one is referred to as bloom phase). Effectively turning it into a dumb machine. If it still does it, more evidence for a water hammer effect due to air…well that's the theory. ***P.S. If you turn off steam boiler…wait until it's below 100C***

Thanks for all the continued feedback and interesting information, everyone. Also glad (sort of) to hear I'm not alone. DavecUK, this happens even when using no preinfusion of any kind, and also with steam boiler off and cool.

I will keep an eye on mine. I never noticed this. But then again, I only have one coffee in the morning, and one in the afternoon. If there’s any testing I could do, please just let me know. 👍

@"Pygmalion"#p1333 If that is the case, I can only assume it must be a transient water hammer effect type of thing due to air? I would expect it to have no impact on the shot. Any chance of video of it doing it?

Lelit Elizabeth pressure spiking/inconsistent

MediumRoastSteam

DavecUK means it’s the safety valve if your steam boiler has one silicone tube from the boiler to the vent above the drip tray

That’s not the case on the Lizzy. See my post above.

MediumRoastSteam

DavecUK If the vacuum breaker is also routed there

Yes it is. 😉 - as per my earlier post.

vinterben

Thank you so very much, @MediumRoastSteam and @DavecUK - I really, really appreciate your help on this matter 🙏🏻

I’d love to give you an answer/picture, Dave, but I’ve just emailed the retailer instead with the description, videos and your both’s explanations. I’d rather not open it and be held accountable for anything :D

I’ll let you know how it goes - but thank you so much!

Have a lovely day :)

Best
Jacob

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