I have a Linea single group. I have taken great pains to get the brew temp to 92c. When I make multiple shots, after about the third shot, I start getting great consistent shots. My problem is that during the week, I only make two shots and then go to work. I'd rather not waste coffee so my question is, how do I stabilize the machine to its working temps without pulling three shots? Is there a technique I should be using to bring an idling machine up to speed (assuming a dual boiler like the Linea)?

Thanks for any tips, I could use all the help I can get!

I would have to say just like my large machine that to be stable you have to pull shots. That is the way they were designed. You may be able to heat it up quicker if you put some type of resistance in the PF as you do your warming shots. But nothing will beat using hot water to get the group up to temp. It is a trade off you have with a commercial group in a idle setting.

I guess you could add some type of heater to the group like a few of the newer cross over models are trying, but you would be doing the engineering on your own there.

-Cecil

You could try three back flushes.

In my machine, if I want to speed the warm up time, I place a towel around the head. But don't know about the Linea.

Eric's Adapter is very useful for quick group warm ups, since I can run the pump till I hit the right temp. In your case, you may have to rig something like a Scace adapter. In my case, there is 6.5F gap from the adapter to the coffee. Maybe you could tap in close proximity inside the machine with a fitting or washer type thermocouple and bring out the thermocouple with a reader like this one:

http://www.thermoworks.com/products/handheld/mtc.html

Once the temp is close, there is almost no delay. That would give you an offset temp to read and run the pump

Cheers

I've used flush... wait... flush... wait schemes to simulate a couple initial extractions, though it's an inexact method. You could improve on an unimpeded flush by plugging all the holes of a single basket until it's close to normal flow rates.

mitch236 wrote:I have a Linea single group. I have taken great pains to get the brew temp to 92c. When I make multiple shots, after about the third shot, I start getting great consistent shots.

That machine should have excellent temp stability after a 1-2 ounce flush.

Have you measured the temp of the first 3 shots to confirm a difference?
Let me ask this - what is your cleaning regimen like? Do you use detergent daily?


I'd suggest maybe pulling the screen and looking at the dispersion block to see if it needs cleaning.
You also might check other components in the brew path to ensure that the issue isn't caused by stale coffee oils that get washed away by the first two shots (into your cup).

And how long a warm-up period have you allowed? There is a lot of metal in there to get up to temp.

ähem...stupid question? why is there need to flush a linea? it has a saturated group head and should be temperature stable no matter how long its ideling? or do i miss something here?

else: if u are not happy with your single group linea u can sell it to me

13thfloorelevators wrote:ähem...stupid question? why is there need to flush a linea? it has a saturated group head and should be temperature stable no matter how long its ideling? or do i miss something here?

Nothing is perfect....from my understanding the group screen/block area apparently lowers a few degrees when idle for a period, but just a quick flush of 1-2 ounces warms it up nicely. Same thing for GS3

The old Lineas were much tougher than the GS3 or GB5, since the brew boiler is fed with cold water. Flushing large volumes drops its temperature very fast. Find a restricted basket, or make one by putting a pinhole through a back flush basket, and flush once through it. The slower flush will warm up the group just as efficiently, but without screwing up the brew boiler.

This advice courtesy of alt.coffee, circa 2002.

The Marzocco manual says you have to run the group after a 30 minute rest to bring it back up to temperature. Saturated groups rely upon circulating water and thermal conductivity of the group material to move heat from one place to another, like from where the temperature is measured to where it is dispensed.

Stainless steel is awful for transferring heat energy, which is why the older non welded Marzoccos were more stable than the new ones.

HX machines tend to rise in temp from non use as the thermosyphon doesn't stall. It is all about balancing temperature profile capabilities of HX designs to match usage. Home use of commercial machines requires an accommodation outside the expected duty cycle of the machine.