AssafL wrote:You are separating the "Brew" cycle and the GIcar controller: One of the things that would be concerning is since the two operate independently is that the autofill valve may decide to fill the steam boiler while the pump is operational - causing a pressure drop on the puck. Perhaps you can cut power to the autofill valve?

You are very close to completely replacing the Gicar - just add control for the autofill and tea water solenoids - and 2 PID loops (and a steam water level A2D). (Just my tuppence - can add a lot of functions once we are in Arduino land...).

Assaf

You missed this in my post:

Peppersass wrote: The relay will switch AC to the 3-way and will interrupt AC to the autofill solenoid (the CPU suppresses autofill during the brew cycle, so I need to do that in untimed mode.)

I would need more sensors (optocouplers) and wires to take complete control. All I want to do is bypass the 50 (or 55) second limit. I'm happy to leave the rest of the job up to the CPU.

Actually, one of the issues with my attempt to simulate the Slayer slow-preinfusion protocol is that at the very low flow rate required to do this the water going to the coffee boiler spends too much time in the heat exchanger and gets too hot. When it gets to the coffe boiler it's superheated and makes scary noises when it hits the colder boiler water. Probably benign, but I don't like the sound.

Indeed I did miss the point about the relay to switch the autofill function off.

Actually, one of the issues with my attempt to simulate the Slayer slow-preinfusion protocol is that at the very low flow rate required to do this the water going to the coffee boiler spends too much time in the heat exchanger and gets too hot. When it gets to the coffe boiler it's superheated and makes scary noises when it hits the colder boiler water. Probably benign, but I don't like the sound.

On the hot water tap side of the machine there is a water mixer connected to the heat exchanger. There is also a giggler in it. See below.

I never figured out if it is adjustable - but if so perhaps you can reduce the temperature by increasing the cold to hot water ratio in the mixer (or replace the giggler with one with a smaller orifice?).)

BTW - I am going to buy and install a regulator to get the pressure down to 1-2 bar and do prolonged preinfusion. I have been contemplating doing this (as well as a gear pump) ever since the whole flow profiling vs. pressure profiling discussion took place. I did do prolonged preinfusion under main line pressure for the last two years and indeed it is a substantial improvement in repeat ability (as well as the ability to grind finer and get a better cup).

I never figured out if it is adjustable - but if so perhaps you can reduce the temperature by increasing the cold to hot water ratio in the mixer (or replace the gicleur with one with a smaller orifice?).

It does have an adjustable pin. According to the parts manuals, that valve body, pin, and o-ring are identical to those contained in the tea-water mixing valve.

See the parts manuals or this: /downloads/ ... aulics.pdf

It would be interesting to learn the methodology behind the adjustment of that valve given the variances in steam boiler temperature and pump water outlet temperature across all users.

Peppersass wrote:Actually, one of the issues with my attempt to simulate the Slayer slow-preinfusion protocol is that at the very low flow rate required to do this the water going to the coffee boiler spends too much time in the heat exchanger and gets too hot. When it gets to the coffee boiler it's superheated and makes scary noises when it hits the colder boiler water. Probably benign, but I don't like the sound.

I think we've talked about this before. I don't think this is an accurate understanding of the problem. The problem is that when you cut the line pressure too low, the 0.6 mm gicleur in the GS/3 allows too much flow, failing to provide enough back-pressure in the boiler and preheat HX tube to keep the boiling point of the water above the actual temperature of the water in the HX. So that water flash boils, making a grating, weird gurgling noise. It's no coincidence that this sounds like a muffled version of flushing an E61 that's been idle for a long time. It's harmless to everything other than your ears.

Interesting that the diagram posted by AssafL shows the gicleur in the upper tube. The parts manual shows it in the lower tube. Probably doesn't matter, but interesting nonetheless.

The parts manual doesn't show the gicleur as an update, but I think my machine (#613) doesn't have it. I didn't see it when I removed the tubes to get the HX out to replace the boiler seal on that side, though I might not have peered into the stainless block. I vaguely recall seeing it listed as an update in a tech bulletin, but it seems that the tech bulletins posted on the LM USA site are only the most recent ones. Can't find tech bulletins on the main LM site, either. Does anyone have a link to the complete set of technical bulletins?

I've also forgotten why that gicleur is there. Can anyone refresh my memory?

Presumably, it slows down the flow rate, so I'm wondering how that would affect the flash boil thing if it's there or not there.

From the same update document:


Dick - according to this document and your serial number I assume you should have the Giggler in your machine. I don't remember the giggler as well and mine is SN 602.

From what Shadowfax was saying, and assuming La Marzocco is correct that the temperature of the water flowing into the coffee boiler (from the thermostatic mixer) is close to the 92-95 degrees of the coffee boiler - I would deduce any water boil and vapor cavitation noise would come from where the superheated water would encounter the colder water which would be in the mixer.

For this to happen, the pressure in the mixer would have to be less than the vapor pressure of the superheated water, which at this point (since some heat is lost in the pipe and giggler) would be under the boiler pressure (<1.5 bars). So your mains pressure (after any regulators) would have to be lower than the steam boiler pressure. BTW - You could verify this by reducing the temp to the steam boiler and that should stop the noise....

erics wrote:It does have an adjustable pin. According to the parts manuals, that valve body, pin, and o-ring are identical to those contained in the tea-water mixing valve.

I read the same - whenever I got close to the part and tried fiddling with the little protrusion at the bottom - it didn't seem to want to turn (and I wasn't inclined - nor saw the purpose of trying - to force it to turn).

Hi Dick,
Thanks for posting this. I was wondering if you used a o-ring lubricant when you put the new ring on. LaMarzocco recommended Molykote 111 which is supposed to be a food grade lubricant, but it has some reproductive health warning on it, which seems disturbing.
Thanks,
Mark

Hi all,
Just a reminder that the GS3 (while using the water reservoir) with pre-infuse at 1.5-2 bar with the pump off. Essentially it is what ever the steam boiler pressure is.

BillC

espresso-shots wrote:Hi Dick,
Thanks for posting this. I was wondering if you used a o-ring lubricant when you put the new ring on. LaMarzocco recommended Molykote 111 which is supposed to be a food grade lubricant, but it has some reproductive health warning on it, which seems disturbing.
Thanks,
Mark

Unfortunately, I don't remember. If I used any lube it would have been the brand sold by Chris Coffee.

shadowfax wrote:I think we've talked about this before. I don't think this is an accurate understanding of the problem. The problem is that when you cut the line pressure too low, the 0.6 mm gicleur in the GS/3 allows too much flow, failing to provide enough back-pressure in the boiler and preheat HX tube to keep the boiling point of the water above the actual temperature of the water in the HX. So that water flash boils, making a grating, weird gurgling noise. It's no coincidence that this sounds like a muffled version of flushing an E61 that's been idle for a long time. It's harmless to everything other than your ears.

It is much easier to overcome strange and odd behavior when you expect it to happen. So when I finally received the Watts regulator and fittings (way easier when I resided in the Bay area - economy shipping abroad takes weeks if not months...), which allowed me to reduce pressure to the 1-2 bar point, I was ready for the strange gurgling noises that emanate from the mixer. So to verify - I reduced the temp of the steam boiler to 95C and the gurgling sound indeed stopped.

I agree the it seems harmless, but odd indeed.