I notice that there are a few versions / sizes of the boiler that installed in President/Urania 1 group head lever machine.
One seems to be shorten and wide, other seems to be longer (the same width) like they are about the size of the frame / chassis.
What sizes and what versions there are?
Why one has type A and other has type B?
What is the original size/versions?

Here are two pictures to demonstrate the two boiler sizes I saw.

Here are the original boiler capacity dimensions in liters for the President, by number of groups, under the column "capacità caldaia":

Thank you very much.

Good question - difficult to answer

Faeama-Style: Whatever was lying around was built into their machines

The photo of Doug Garrot shows a 5l boiler with an inserted HX with a hole - open HX... this was used in the Lambro, but I've also seen it in some late Uranias and Presidents .

The other picture with the larger boiler has no HX, but 2 open tubes ending in the boiler volume.

Both constructions have a circulating waterstream: the thermosyphon.

Then they had the Velox groups, those machines had an extra steam boiler.
Predecessor of Velox was an "Urania senza caldaia" - the boilerless Urania :
https://www.kaffee-netz.de/threads/faem ... nte.86527/

Heck, there were even double boiler constructions of the Urania and the President (boiler config from the Tartaruga model with lever groups).

The single group Urania had two different sizes, the early models were smaller / narrower, you could find the specs in a document in Maltonis "Faema"-book (I don't have a link or pic of it).

Sansibar99 wrote: The single group Urania had two different sizes, the early models were smaller / narrower, you could find the specs in a document in Maltonis "Faema"-book (I don't have a link or pic of it).

Are you referring to this?

The * means that the labeled machine has two independent boilers
The o means that the labeled machine has a 5% price increase

Sansibar and dominico, thank you both very much.
Now I understand clearly why I see two types of boiler in pictures.

Here are 2 machines I am working on now. Same machine but with the 2 different sizes. These are EMI (faema) levers.



It is common for manuf. to offer different sized boilers for the 1 group machines, and also some 2 group machines. To this day you can order CMA Astoria machines with larger boilers and higher wattage elements. Even in the 90's when you ordered from the Marzocco factory you had to specify large steam boiler otherwise you got the small sized one.

Small boiler for home or moderate use, large boiler for a cafe or a bar. For example....

1500w works very well in the small boiler, but you would need 1800W and over on the larger boiler.