Hi,
I have a La Scala Butterfly from 2004. A nice machine, but it needs a gigantic cooling flush of around 400cc. So recently I put a flow restrictor in, in the believe that this would cure this problem. It does make a difference: now I have a cooling flush of around 300cc!

To me that does not make sense, and I find it disappointing. Has anybody something to say about this? Is it possible to put the flow restrictor in wrongly?
For the record: my pressurestat is at 0,9-1,1 , and I put the flow restrictor in the upper tube of the siphon and the fit seemed okay.

Thanks in advance.

The original Faemas E61s and the Faema Classic have needle valves on the lower pipe (there is already a jet and true preinfusion in the head, so an extra restrictor in the path of the shot is not good. Use the valve to restrict the thermosyphon flow more and more until the group head reaches an idle temperature just below the shot temperature you want (the initial HX flow will be hot)

I am not sure what a "needle valve" is, but I'll open up my machine again, and look for it. Are you sure that I have one in my machine?(not being an original Faemas E61s or the Faema Classic).
I asked the Dutch importer about "my problem", and he was the one sending me the flow-restrictor. Seems weird that he would do that, considering it seems wrong. So you say that flow restrictors in a E61 are no good, what so ever?

I'll be back when I know more... thanks so far!

To me that does not make sense, and I find it disappointing. Has anybody something to say about this?

It mostly makes sense. You did reduce the cooling flush, as opposed to increasing it.
Thermosiphons in an HX machine are not a very intuitive, nor linear, phenomenon. One very important facet of their behavior is that we care more about their impact when they're not siphoning, which is when we're pulling a shot. How fast the siphon was moving prior to the shot doesn't just affect the temperature of the group, but also the HX itself.
For a very fast siphon, the bottom (entry) of the HX would be at the same temp as the returning water, and the exit temperature would be below the boiler temperature, and the middle of the HX at some temperature in between. For a slow-moving siphon, the water at the middle and top (exit) of the HX would be near the boiler temperature.
So when you add a restrictor and do a cooling flush with a slow-moving (relatively) siphon, you're initially drawing more hot water than for the case without the restrictor. So you don't necessarily get a cooling flush that's proportionally shorter to the reduction in flow rate.
Thermosiphon Utopia is when the group at idle (while siphoning) is at the target temperature, and the flow rate of pulling a shot is identical to the thermosiphon flow rate.
-Ed

Here is a pic of the adjustable thermosyphon valve installed in some Faema machines, e.g. the E-61 Legend and possibly others.

Some(?) current production Faemas have this valve built in to the grouphead - see several pics here:
http://www.home-barista.com/espre...-enova-t10222.html
A fixed size (~2.8 mm) thermosyphon restrictor is installed on Vibiemme Domobar Super machines sold in the US. This restrictor is located in the upper hx thermosyphon line at the hx end. The size of all fixed size restrictors that I have seen or heard of range in size from 2.0 to 3.0 mm. A 2.5 mm teflon disk restrictor is fitted to some Expobar machines sold in Australia and is installed in the group where the upper thermosyphon line attaches. Here is a discussion of a restrictor installed in a Maver Marte - see pic on Page 5, about 2/3 of the way down: http://www.coffeegeek.com/forums/...ines/265055#265055. It is installed where the upper thermosyphon line connects at the hx end.

Your best bet might be to install a variable restrictor - a la Faema - as you would not be happy with the restrictor installed when you invite the "gang" over for a few shots.

And for those (like me) unfamilar with the LaScala Butterfly, here is a nice depiction:
http://www.coffeeco.com.au/articles/butterfly.html

Uhuh, and as we can see in the bottom picture: no adjustable thermosyphon valve!

This is the big difference between domestic E61 boxes and the real ones: the real ones are tuned to produce a group at the desired temperature. The fixed restrictors on the Domobar may help, but they don't do this. It makes more sense (to me) for the variable restrictor to be on the return side, so I may be misremembering.

It does seem to make more sense to put the restrictor in the lower tube. That way, at least it doesn't hinder the waterflow when pulling a shot, right? It's just that the importer said I should put it in the upper tube.

Perhaps I'll switch it tomorrow, when I have the time. See what happens.

Flow goes via the upper and lower tube to the group.

No valves to stop water from going via the lower tube.
But i think the location does make a difference since the water at the bottom of the HX is cooler.