Understanding a Thermoblock - Voodoo Free Version

[EricBNC]

This wealth of information was mired in a unrelated off topic post so I brought it over here in the proper section - hardware and equipment.

There is a "traveling road show" type of user review in the works for the Crossland CC1 over on CoffeeGeek.  I will be trying out this machine along with some other, more experienced espresso equipment enthusiasts.  There is no drawing for the machine at the end but I am OK with that.  It has a thermoblock for steam like my QuickMill Silvano but does not have a separate steam bank pump so it can not steam and pull a shot simultaneously.  Many home barista's can't either. Here is some food for thought on the use of a thermoblock for steaming.

Is the single boiler double use, HX or double boiler system better than a thermoblock only machine like a Krups or a cheap DeLonghi (some DeLonghi models are SBDU's)? Sure it is. The steam thermoblock in the Silvano has it's basic operations in common with a Krups thermoblock since both heat water  - I have seen both up close (and if everything works out, I will see the CC1 up close too) - the Krups (XP4000, XP4030, 964, 969) system is different in appearance than the one found in the Silvano  - in the photo below on the left courtesy of  Chris Coffee you will find a large circle of gray metal below the red word "bracket" - this is the steam thermoblock - it is found behind the brass boiler inside the machine. On the right is the group assembly of the Krups. The Krups thermoblock is the part sitting above the polished metal group.



Most home use machines with a thermoblock will look similar but the Krups is nicer in build than some cheaper models I have dissected.  These are required to hold a larger volume of water than the steam only thermoblock because this part functions as the entire boiler for the machine. Since the pump must still deliver 9 bar of water pressure, the cooler water from the tank will negatively affect water temperature stability while pulling the shot - hence the bad rap thermoblocks earn for brewing espresso.  Make this block larger and the stability improves - ask it to flash boil only a small amount of water at a time for steaming and the design works very well.

Be wary (and weary) of dogma passed as learned knowledge - a Ford family car and a race car can both have a gas engine, but comparison between the two is more fruitful after lifting the hood to see what is going on inside.

Here is a cool video from Chris Coffee that speaks better than I can to thermoblock steam bank machine's capability:

Silvano by Quick Mill: Making a Cappuccino

titled Silvano by Quick Mill: Making a Cappuccino

And here is a longer overview of the Silvano - Steaming starts at 6:21 and is finished by 6:50 so less than 30 seconds to steam the milk - nice performance by this thermoblock steam heat bank.

Silvano by Quick Mill Overview

titled Silvano by Quick Mill Overview

[Tex]

Ha, more voodoo!

[grinderz]

Don't make me you two! 

[Tex]

IF a thermoblock has enough thermal mass & large enough tubes it can make a decent brew boiler.

I simply have a problem with using a TB as a steam boiler. There are many instances where it's been tried and it just doesn't work well. Picture a boiler used to develop steam at temperature of 250° for a HX, to 300° for a SBDU. That steam is highly pressurized and released through a tiny hole(s) in the wand tip. This highly pressurized steam is what helps the barista develop the creamy microfoam we all want in our frou-frou. The lower pressure steam created by a TB is water-laden and adds water to micrfoam, which is detrimental to quality microfoam.

There are no steam boiler TBs now in use that can develop pressure that equals a boiler. The closest was the Quickmill steamer, but it was in no way equal to a real boiler. If you're still in doubt, just check the wattage in a steam TB dual boiler machine. Even the 1500 watt TBs used in Gaggia/Saeco super autos can't make steam enough to properly foam a cup of milk.

The best TB steamer I  ever saw was in the Lavazza Espresso Point machines, but unfortunately the steam was far better than the coffee.

[peter]

Even the 1500 watt TBs used in Gaggia/Saeco super autos can't make steam enough to properly foam a cup of milk.

That video shows properly foamed milk, at least according to the pour.

[Ascholten]

2+2 = 4

1+3 = 4

4  1's = 4

but some people only see their way to make 4.

Aaron

[blzrfn]

2+2 = 4

1+3 = 4

4  1's = 4

but some people only see their way to make 4.

Aaron

Like 5-1

 

[Tex]

I'll admit the milk looks good, but I was told the TB is the same one used in the Quick Mill standalone steamer, and it produced wet steam. Maybe they put different tstats in the Silvano?

[EricBNC]

I have no illusions that this is the most powerful steamer on the market, but I do feel it is adequate for the average espresso fan. This cut-away is lifted from the QuickMill home page - looks like brass or copper lines inside the thermoblock.



Here is a photo lifted from a Seattle Coffee Gear video showing what the steaming thermoblock looks like inside a Crossland CC1 along with some other parts. Since this design takes heated boiler water and converts it to steam it can be smaller but still be effective.