Jacob wrote:The brochure lists a couple of points where one says "Brew water pre-heating system".
Can anyone tell how this preheating takes place?

Teme wrote:There's a heat-exchanger through the steam boiler.

AndyS wrote:And in addition, there's a hot/cold water mixing device. This ensures that any overheated water from the heat exchanger is cooled down before it enters the brew boiler.

Today I was told (by a technician from a La Marzocco selling shop) that there is no HX and that the brew boiler water is just picked up from steam boiler itself

Can anyone verify if it actually uses a HX or not?
And how about the mixing device, can anyone verify that this device made it into the current production model?


Thanks
Jacob



...split from One week with the La Marzocco GS3 by moderator...

Jacob wrote:Today I was told (by a technician from a La Marzocco selling shop) that there is no HX and that the brew water is just picked up from boiler itself

Can anyone verify if it actually uses a HX or not?
Thanks
Jacob

IIRC he's right and wrong. The group gets the water directly from brew boiler, the brew boiler get's it's water via HX so it doesn't have to heat as much and hence yields more stable brew boiler temp.

miKe mcKoffee wrote:IIRC he's right and wrong. The group gets the water directly from brew boiler, ...

This don't make him right we're strictly talking preheating of the water going into the brew boiler.

This guy has put up several of these machines, so normally I wouldn't questioning him and he is to be taken seriously. To clarify that this is not a misunderstanding on my part; the remaining of that part of the conversation were about the pro and cons of using steam water to brew coffee. I would hate to see him wrong, but I don't like having some additional 3 liters of hot water in the brew path neither

But he MUST be wrong! Otherwise the pump had to pick up cold water to fill the steam boiler and hot water from the steam boiler to use in the brew path - no way!

Jacob wrote:But he MUST be wrong! Otherwise the pump had to pick up cold water to fill the steam boiler and hot water from the steam boiler to use in the brew path - no way!

No, the pump pushes cold water to a manifold. Depending on what valve is open that water either:
1) fills the steam boiler for steaming
2) enters the hx pipe running through the steam boiler, pushing the hot water in that pipe into the brew boiler, pushing hot brew boiler water through the group
3) enters the mix valve for the tea tap.

This is how Synesso's work; I'm sure the GS3 is the same.

Just for the record

Here we see the two mixing devices and the main connections.


The connections going in and out of the picture are:
- Fresh water is coming from the pump trough "A".
- The tea water is drawn trough "D".
- "G" feeds the brew boiler trough a T-connection which also connects to the expansion valve.

Nice pics,

I would think that the cold water going through "Y" is splitting "G" with "H" & "I" being the pre-heat exchanger loop. If thats the case, I'll bet there's an adjustment in "Y" to meter how much of the really hot heat exchanger loop water is mixed with the cooler water being piped in "F".

Synesso doesn't have mixing control over the heat exchanger loop. I would like to see this, as sometimes if you're not moving much water(home enviroment) it enters the brew boiler way over heated.

I don't think it's best to use copper if the water being transported is heated, to me stainless imparts less flavor to the water. That's one thing the Synesso has over the GS3 in my opinion

The two mixing-devices looks pretty equal except from the adjusting wheel (Xa=Yf, Xb=Yh, Xd=Yg, Xe=Yi). My guess is that they work the same way and I hope it's possible to adjust the pre-heater mixer?

The tea-water mixer is the more obvious of the two and must work this way:
Fresh-water entering "A" and goes unrestricted through to "B" where it splits in two; one continues strait ahead to the flow-meter and the other goes through "C" to fill the steam-boiler. Inside the mixing-device the hot water coming from the steam-boiler through "E" is mixed with the cold water (going from "A" to "B") before leaving through "D".



If this is correct, the output ("G") is a mix of cold water from the flow-meter ("F") and hot water from the preheat exchanger loop ("I"). Just like Jepy suggest - if I'm not mistaken.

Left side:


The famous wand-mounts:


I got false refill-warnings but I found an easy solution, just add a nut to the end of each of the two 'contact' bolts:


I had a little rattling from trays and cups and I wasn't aware of this item, until Teme mentioned it on CG:

Teme wrote:Ask your dealer for a pump support - a small plastic part that will take away the vibrations and resonances. If he isn't aware of this part, ask him to contact LM. Again, this is very easy to slip under the pump (you will just need to remove the left side panel to gain access) and it will make the machine as quiet as the full-size commercial LMs with external pumps.

My pump had a hard time starting up from cold, so I got a new heart (under a Danish 2 year warranty):


Not much space left - ruler indicating the side panel: