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Author: La_Maudite (
Date:   05-27-02 16:06

danny ( wrote:
> Assuming a standard boiler setup...Theoretically, any boiler with a
> capacity large enough to dispense a double or two without tripping the
> boiler fill sensor should be stable - the water dispensed throughout the
> shot is the same temperature, unless the boiler fills with fresh water, so
> I'm not sure what difference a 4l boiler would have over a 2l, apart from
> possibly in the sense of pulling shots whilst steaming simultaneously.
> Obviously the larger the boiler the less the temperature difference will
> be when it admits fresh water (as long as it admits little enough to
> replenish it). My Gaggia in the trailer (16litres) will dispense approx
> 8-12 ozs before the autofill trips, enough for several espressos, and of
> course the water replenished won't have much affect on the remaining 15
> litres or so in the boiler.

moosemake ( wrote:
> Note, danny doesn't have a heat exchanger in his lever pull machines.
> Regarding heat exchangers (which for pump machines are the only kind
> that steam and make coffee without adjustment in the boiler temp), a
> lot of the question of thermal stability depends on the kind of usage.
> What works at home for the occasional shot or even several shots in a
> row would be unlikely to require the size of boiler that would be
> essentially necessary for a busy commercial establishment.
> 2L boilers are plenty big in the home and 4L is really overkill
> (though we've been known to indulge in this NG).
> 4L boilers for one-group machines would handle low volume commercial
> needs fine, but would be way too small for a busy cafe, particularly
> one that sold a lot of milk drinks.
> In general, the larger the boiler, the more powerful the steam
> production and the less time needed for recovery with either prolonged
> steaming or lots of shots in a row. Big/small can only be gauged in
> the context with which the machine will be used.
> There are other parameters that fit into thermal stability, such as
> thermosyphon (E61) or other active heating of the group (e.g. La
> Marzocco) and overall group and portafilter weight, as well as the
> speed with which the barista moves to load the PF and lock it into the
> machine.
> My machine has a 2.5 liter boiler. For my own home use as the sole
> coffee drinker in the house it's HUUUUUUUUUUGE. Bye.

JR ( wrote:
> I second sasha's point. The 1.9 l boiler in my Oscar is more than
> sufficient for home usage. Unless you are running a commercial
> operation, 2 litres should be fine. HE machines overheat when sitting
> idle, but a lot of single-boiler home machines also get too hot. You
> are going to have to play with any home machine to get the water temp
> right. Think of it as craft work.

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