Probably more than you realise
Per Reiss's latest recommendation, I have shortened my preinfusions from 6 to 10 sec down to 3 or 4 sec. I often do three or four shots a few minutes apart. If I do a short (1 sec) flush after each shot, the group surface temp seems to stay steady at about 188F (86C). If I don't do the flush after each shot, the group surface temp often drops to 181F (83C) or below. So, of course, I've gotten in the habit of doing the short flushes.
How or why people like fransg and kfir experience superior temperature stability with their machines is a mystery to me. I will say, though, that despite the temperature management inconvenience, I like two things about the L1:
1. quality of the massive group
2. taste of the espresso
And those things are why I am still using it on a daily basis.
Anyone here have a physics degree? anyone...?
I know you're modding an Achille soon for Chris and it will be interesting to see if the same issues arise - please keep us posted on the progress.
In the saturated environment of the boiler gram for gram the steam contains significantly more energy than the water does. You could see significant differences in the temp profile of the shot depending on how the machine is set up and how much of the HX is exposed to the steam and water. What the exact difference will be will vary one machine/setup to another. Only testing a specific machine/model will tell you how it responds.
Java "Physics is fun!" phile
Toys! I must have new toys!!!
I suspect you would reach equilibrium temperature either way.
Something else I've just thought of; if the element is off for an extended period, perhaps a temperature gradient develops in the boiler due to reduced mixing, which would slow the thermosyphon flow? It could be that a bunch of these factors all combine (that swiss cheese effect again) due to small fabrication differences (and a sensitive design) to cause stalling in some machines, but not others.
Quite an interesting discussion, but could really use some schematics/details photos of the boiler/HX
Last edited by MrJack; 6th August 2013 at 08:21 PM.
...but i acknowledge that your practical test suggested otherwise. !
These convection loops need a vertical difference between the heat source and the heat sink in order for gravity to work its magic, and they work better with increasing height distances. Most HX/TS systems i have seen run the cooled return line down low to the bottom of the machine in order to improve the convection effect. ( not so the L1 !)
Am i correct in thinking that when a shot (or a flush) is pulled, the feed to the group comes mainly from the RETURN side of the TS ....to prevent the brew water coming straight in a boiler temperature ? ..( i think there is a flow restrictor in the HOT feed line )
BUT, if this is so, since the HX refills from the boiler, the cool "return" line will actually be refilled with HOT boiler temperature water !
This would create an even temp' in both feed and return lines. cancelling out the convection effect, and effectively "Stalling" the TS loop.
Worse,.. the actual flow "inertia" of water up that "return" line to the group may well impart a reverse flow impetus in the TS loop.
Your cold water feed to the HX(TS) loop would have eliminated this tendency to increase the temperature in the return line, and encouraged the convection effect to continue. ??
I think you might be on the money Blend52...
The return line isn't at the bottom of the boiler? (that's just silly)
Isnt it unusual for a "tuned" TS loop not to have a restrictor of some sort ?
But even without a flow restrictor, the "brew" water feed to the group will still be drawn from BOTH of the TS lines , evening out the temperatures.
The amount of air dissolved will be very low, and will mostly come out of solution in the boiler (as gas solubility decreases with increasing temperature). Its not implausible that air could enter the loop, issue is whether the small fluctuation in boiler pressure resulting from pulling a shot will increase the volume of gas in the system, and whether this change will have a noticable effect on the thermosyphon. I doubt it.
I imagine a tee with a small diameter line branching off at the highest point in the loop (or close to it) would work if the flow is slow enough. A bleed valve or threaded end connection could be used to periodically bleed the system.
There doesnt appear to be much "tuning" of TS pipe lengths on the L1..just some simple direct pipe runs.
Air in the TS...
Is it not likely that there could be air trapped between the brew water and the piston in the group when the piston is raised.. and when the piston is released, some of that air is forced ( at 10+bar) back into the TS loop before the piston covers the ports. ??
Fine setting of piston height relative to port position ( gasket thickness, machining tolerances, etc) could make a significant difference between machines for this.
A post-shot flush would also likely purge any residual air in the group. And, as Andy said, at higher pressures this air, if present, would have less chance of playing havoc with the TS flow.
Whilst the piston is lifting, there is nothing but air in the group chamber..until the ports are uncovered near the top of the travel.
To be honest, i dont see how the brew water can expel all the air from above the puck, ! since the air will naturally rise above the water .
Is there some feature to allow any trapped air out up past the seals ?
Any air left under the piston stands a fair chance of being forced back through the ports and up into the group. Once there, gravity/buoyancy will effectively move it up into the thermowell and TS loop.
Your "mains feed" mod would also reduce this tendency due to the higher pressure in the TS.
If that channel from the thermosyphon to the chamber is small enough, the flow of water might prevent the air from travelling back up. Even with no flow, surface tension could do the job (think a finger over then end of a drinking straw).
Well it certainly is not happening often, and this is all speculation, but if for some odd reason there is enough air under the piston, for a brief period when the piston is released, there is 10+ bar of pressure to help that air back up into the group.
And why else would a flush be recommended, other than to purge any air out of the group ?
It probably wont be at 10 barg initially though.
Going from atmospheric pressure to 10 barg, the volume of the air would reduce to around 1/11 its original volume - the piston design might therefore accommodate this, preventing the air interfacing with the port (thoughts?).
If air entering the thermosyphon is a problem, I wonder if a sealed vertical tube in place of that hex bolt in the diagram, would help, by acting as a strainer?
MrJ' ...true, but it depends how much air is trapped in there !
.... and remember this .....
Can anyone explain how the air under the piston is displaced when the brew water fills the chamber ??
It would seem like a good idea, even just as a precaution.
Rick, the air will be above the water..how can it be pushed through the puck ?
I don't understand the thermodynamics at work, but trust me, that's what happens. Take a lever machine, a spouted group handle and put a cold glass under the spout as water enters the chamber, you'll see the condensation form as the air is pushed out.
Water flashing to steam perhaps? It will happen as the water reduces in pressure.
Had the opportunity to have a session on the 'Australium' yesterday at CM's workshop.
What a difference Rick has made to the performance of the machine.
The quality of the group has never been in question and with what Rick has achieved, I was able to vary the dose and tamp and still
pull really great shots. Smooth, sweet, rich and full bodied and very forgiving.
Still looks ordinary tho'.
All it needed was some intuitive, intelligent tweaking (as Rick outlines above).
I would love to see an Aussie designed and engineered machine, using this group, something that would
be a shoe-in at the very top of the lever market.
Interesting developments from the L1 blog:
The Luxe is also now discontinued, the machine Andy received is looking more and more like a prototype. Improvements based on user feedback, sure, and good on Reiss for pushing Fracino to use better / more complex construction methods for the panels, but that has to hurt for the early adopters.If you place an order for a LONDINIUM I now it not only comes with solid wenge handles, but in the interests of burnishing its compact commercial credentials, it now comes with pop-off panels which attach to a subframe just as you find on a commercial machine, which gives the machine all rolled edges (i.e. no raw/cut edges) for a more refined look
As previously posted LONDINIUM I now comes with three LED signal lights, white (power), blue (water inlet solenoid open), and red (immersion element on). These lights have all been moved closer to the centre of the machine for ease of visibility, as has the manometer
The drip tray is also slightly different, with the 45 degree up stand on the back removed as a result of customer feedback, and a slightly different grate
Thanks for the update Rick.
It also puts egg on the faces of all those people around the globe who tried to give Andy grief over the review I wrote.
Although I didn't get into the technical details, that's for experts such as Rick, all I did was state the bleeding obvious.
Now look what's happened………… and I'm sure it wasn't the only L1 that was questioned over (aspects of) design, build quality and temp stability.
Hurrah, for customer feedback! ;-D but I agree with your sentiment, Rick, re early adopters. :-(
I knew it I knew it I knew it…:-D
Ever try tell a Mutha she's carrying an ugly baby? : huh
Ever bought a ver. of windoze 'before' the first 'Service Pack'... : tear hair
Or perhaps the first year of a brand new model car... AU... (Ford not country) : puke...
Or perhaps you just sobered up after the honeymoon... : eek
Life's like that.... : pan
Extremely happy with my L1. Even happier that it was only 3K which is about half of the other lever which is was considering.
I like the Volkswagon Amorok- 4wd double cab ute. I am a long term member of AusAmorok forum and have the same avatar. Anyway, This car was sold around the world for over 3 years before it was sold in Australia- apparently to 'prove' the vehicle.
It was marketed here as 'Proven tough in Dakar', etc by VW Aus.
The Marketing was amazing, and in hindsight appears to be a croc of s$@t.
Now some years later it is absolutely clear those 'first adopters' got quite a 'buggy' version of the vehicle... The current resale on those 'first adopter' vehicles is horrendous. This is a $40-$50k vehicle and people are losing many tens of thousands at re-sale. There have been more than a few catastrophic failures of engines because of a stupid design fault on the timing belt cover. A small stone gets in and bang- engine kaput. Numerous gearboxes because of stupid design/placement of a slave cylinder inside the bellhousing, etc, etc this is a multi-multi- million dollar design/production team and they have made some amazingly stupid and in hindsight glaringly obvious mistakes... It happens....
Yet, Others have invested tens of thousands pimping or modding their vehicle and they love them, warts and all. They mod their vehicles grudgingly or cheerfully, either way.... It happens... And individual vehicles can have enormous performance improvements because of it....
For some people they have had no issues and don't understand what all the fuss is about?
My point is like it or hate it, this is how things are.
This is how the world works- whether it's a new 'high-end' consumer coffee machine or even a high-end vehicle from one of the worlds largest car manufacturers...
Over time, the manufacturers are making small and sometimes large changes and improvements in the product... And so they should...
I don't see any VW Aus. Executives putting their own name up for direct contact.....
I don't like many things Reiss has done and I definitely have a love/hate thing going with his machine (I don't own one),
But man, the guy has some big Kahunas and I admire and respect that...
I'd give him a little more slack than some others are want to do....
The only Londinium I have seen is Andy's. I did get to see Rick's before and after data we also have this thread to see what Rick did to the machine to get it to work well.
For mine, out of the box, there is no comparison to the build, performance nor finish of the Alex Leva. It's not even significantly cheaper.
I'd be surprised if you'd require fingers and toes to count Londinium stock in Australia.
'LONDINIUM I will always be the machine that people refer to as 'the one CoffeeSnobs forum tried to kill at birth
That's some grudge Reiss bears. I say if his machine is a success then good luck to him. Ther are plenty of happy users out there. The L1 was a machine I was quite interested in until...wll, you know .
Here's another perspective.
Australium - Yeah mate, it's much better than a Londinium Luxe
As to the ego aspect, it is prevalent everywhere. Some mistakenly think it works to their advantage, but there are many customers who can easily see through this and simply decide not to buy from people or companies with such an attitude. It also applies to this forum.
Given this thread was quiet for so long, posting about the blog post is certain to rekindle interest in his product.
Personally, I gave up reading his blog long ago, as the undertone irritates me. There are a couple of companies in the coffee business who regularly issue a newsletter. These are interesting and informative; and I enjoy reading what people like Alan Frew have to say.
Just wondering Rick and Andy, if you have seen this blog
Not till now. Wow, what a tosser he is. This was never personal, the expensive machine was a dud and it took a pile more expense to make it work like it should have when it arrived.
I do find it interesting that many of the (obvious and stupid) problems that we found in the first model were fixed in the following builds... but I don't remember hearing thanks for the development work
Here's hoping that machines he ships today are working far better and if our input helped deliver a better machine than that's great news for the consumer.
Oh well, as Andy says - What a tosser....
As someone who watched the development of Londinium I (and the blog)from the ground up, and waited patiently to order one, Reiss bitter post doesn't surprise me. Although I was very keen to order a Londinium, I did find the constant condescending tone irritating. Early adopters complaints of siphon stall were ignored until they could be ignored no longer and changes to the design were eventually begrudgingly made. The whole fiasco (and Andy's saga) made me lose confidence, and so when the Alex Leva hit the market it was a no brainer. Very little difference in landed price, and with local servicing if required. I'm sure there are now many happy Londinium I owners out there, but contrary to Reiss constant assertions, it ain't the only current Lever capable of producing top espresso (and with early production models clearly failed too often).