So, I contacted La Marzocco directly regarding the 954 kit a few times. At first they said it was going to be available soon, then they said they'd backorder it for me so, contact LM if you want one. This kit is to retrofit the new conical valve to older GS/3 MPs. The kit itself is pretty extensive, replacing almost every part in the group. This includes the group cap, exhaust & inlet tubes, even the adaptor on the base of the group. Having said all that, the kit is somewhere around $1000 which is pretty steep. We do own $8k machines but still, a fair chunk of change.

Installation is easy if you know your machine but, kinda stressful if you're not used to digging in the group. I've done work on my machine (servicing group, etc.) but nothing super hard core and am generally pretty good with mechanical stuff. I usually take the required tools with a grain of salt but, be forewarned, you *need* the long 22mm socket. You can work around the 36mm socket (but you're better off with it).

The install instructions aren't the best, they're not really clear on some things. For example, on the bottom of the actual SS conical valve, there's a hole on one side but not the other. Because the valve isn't uni-directional, you have to install that facing front or back. The instructions appear to show it facing the back but, this isn't made clear. Additionally, the brass cap is completely omitted with the new conical valve so, it just goes missing from the pictures without much explanation.

The pump switch needs to be move a loooong way from where it was even with I was attempting PI with the old valve as the new conical valve opens almost instantly after moving the paddle.

The instructions show the o-ring for the exhaust valve should be fitted to the exhaust valve when you're inserting it into the group but, this doesn't really work given that you have to fiddle with it a lot to get it seated properly. I ended up with a leaking group because (I had to debug this) the o-ring wasn't seated correctly so, water was just leaking out from the exhaust. Eventually, I figured out that it was the o-ring and, mounted it directly to the group first and then installed the exhaust valve. The exhaust and inlet valves change sides on the housing for the conical valve so, you need to install the new one.

I've found that, while pre-infusing, the valve exhausts *a lot* of water to the drip tray, I feel like it's basically pumping everything out to exhaust that's not going through to the puck which seems pretty wasteful. I think this is because I've got the install wrong but, considering that I've installed and pulled it apart multiple times to debug the leak I mentioned above, I feel like I've followed the instructions to the best of my ability. I'm going to move the switch and hope that having the pump on earlier in the paddle throw will have the exhaust valve blocked off.

I'll likely get in touch with LM about this to give feedback on the instructions. I spent 8 or so hours trying to get it installed but, a lot of that was taking stuff apart multiple times to work out where leaks were coming from, etc so, it's really only a couple of hours if everything goes smoothly.

So far, I'm happy with the kit but, more so because I know my machine WAAAAY better now.

In case you haven't seen it already, the forum in Germany has been discussing this LM-954 conversion kit quite a bit. There are some photos and specific details about the install here (in German, sorry): https://www.kaffee-netz.de/threads/la-m ... st-1375161

Let me know if you have questions about what they're describing, since Google or your favorite translator might not do very well.

Also, with regard to high flow through the exhaust valve at the beginning of paddle travel, it seems that is the normal behavior that others are seeing too: https://www.kaffee-netz.de/threads/la-m ... st-1380022

With the original MP design, at the beginning of paddle travel, the pump is basically fighting against a closed valve and the passage to the exhaust port doesn't open until you move the paddle further towards the left. The new conical valve is a completely different concept. At the beginning of the paddle travel you have nearly a direct path to the exhaust port and as you move the paddle to the left, you begin diverting more water away from the exhaust port and towards the puck.

It's rather unfortunate that LM USA isn't offering a better price for the conversion kit. Until April 30th, there was a special intro price in Europe and the kit was far less than $1k, even considering the exchange rate.

PM sent.

Cheers,
Chris

No more promo price I guess

https://lamarzocco-e-teile.de/LM954

Wow, I was really looking into this retrofit but I don't think I can justify $1000, hopefully an introductory price will make it to the states. What was the intro price in Europe?

DanielCroft wrote:I've found that, while pre-infusing, the valve exhausts *a lot* of water to the drip tray, I feel like it's basically pumping everything out to exhaust that's not going through to the puck which seems pretty wasteful. I think this is because I've got the install wrong but, considering that I've installed and pulled it apart multiple times to debug the leak I mentioned above, I feel like I've followed the instructions to the best of my ability. I'm going to move the switch and hope that having the pump on earlier in the paddle throw will have the exhaust valve blocked off.

You didn't get the installation wrong. The cutaway drawings I've seen of the conical valve indicate that Jay's explanation is correct. The entire flow is divided between the group port and the exhaust port. When the size of the group port opening increases the size of the exhaust port opening decreases, and vice versa.

You might wonder why LM doesn't simply rely on the rotary pump bypass valve to divert the excess flow when the group port is only partially open. That would work, but my theory is that they don't do this because it would result in the flow being too low through the heat exchanger in the steam boiler. As a result, the water in the HX will superheat, and when it hits the colder water in brew boiler it will burst into a boil and make nasty banging sounds. This is avoided by running water at full flow rate through the HX. When the group port is restricted, the excess flow is dumped to the exhaust port.

I can easily demonstrate the HX flow rate problem with my modified GS/3 AV, which has a variable-speed gear pump. I lower the line pressure to 1-2 BAR, open the 3-way brew valve and set the motor speed to zero (this is what I do for long, slow PI.) It always results in nasty banging noises. But, if I run a large cup of tea water, the cold water autofill will reduce the steam boiler temperature enough so that that banging noises don't happen. Pretty much proves the theory.

I've moved the pump switch as far over as I can but the pump still doesn't come on early enough. I wasn't sure what I changed when I did the strada upgrade to my GS/3 but I thought something about the switch position changed. In any case, it's kinda moot as I likely won't pre-infuse if all my water is being diverted. I wish I could plumb my machine but, the water here is awful, even when filtered.

No special pricing for us, apparently.

I'll contact LM tomorrow and chat with them about the instructions and, pump switch position.

Whoa. I was totally on board with this upgrade, until I saw the price. Officially not worth it. I get that this stuff costs a lot in R&D, but $1000 is steep, even for someone who owns a "$8500" machine.

I'd sooner sell the LM, and upgrade to a Slayer. The difference being a few thousand dollars, would be negated by the "upgrade cost" of the conical valve. - I expected a decent cost to upgrade the entire group, but $4-500 would have been much more reasonable.

Anyway, those of you who currently have the "Strada Mod" who upgrade to this conical valve, write up your findings, and differences, love to hear if its really worth it.

(Incase anyone from LM is reading, give us some feedback... Is there is going to be any discounts at all? - If we upgraded to the strada stuff already, is there potential to bring price down, by not purchasing duplicates (pressure gauge, group cap, etc))

DanielCroft wrote:I've moved the pump switch as far over as I can but the pump still doesn't come on early enough. I wasn't sure what I changed when I did the strada upgrade to my GS/3 but I thought something about the switch position changed. In any case, it's kinda moot as I likely won't pre-infuse if all my water is being diverted. I wish I could plumb my machine but, the water here is awful, even when filtered.

Normally for the "Strada Mod" you flip the switch around the other direction and also change the wiring such that a closed switch is off (switch has 3 wires, 1 not used depending on whether you want closed to be on/off). Did you reverse this, i.e. put it back to the original configuration?

So if you just buy a new GS/3 MP will it come with that valve, or is it an add on?