I thought Id start a separate thread on this as I think that there is a widespread lack of appreciation of just how differently hx machines can be designed and the effect that this has on usability, flushing and extraction temperatures.
I have a lot to learn too but have started to think seriously about what makes these machines tick after getting my Bezzera BZ-40P up and running on Thursday.
This machine has an hx which is a 2cm x 24.5cm copper tube mounted horizontally in the boiler (fully submerged)with an end cap where the inlet and outlet are. *The inlet consists of a 13cm PTFE tube (to avoid too much mixing of incoming cold and outgoing hot water). *The outlet simply comess off the endcap.
The interesting thing about this design if that the hx NEVER gets too hot. *The downside is probably it overdrawing it could cool it too much although I dont think that this is a problem in normal operation.
It seems to need a 50ml blank flush to warm up the group/portafilter and flush the 15mls of water in *the pipe from the hx and then it is ready to go.
Anyway, if anyone is interested in posting their findings with their machines, any pictures, schematics etc, I would be interested.