An HB member mentioned that he had pulled 30 shots with minimal breaks while testing a BDB, pausing only to add water (actually there'd be no need to pause, as you could do it while a shot is pulling, easily filling from the top-front). My thinking is that the steam boiler would be the limiting factor; at some point water would have to be drawn in and heated. In my case, it would be to 185°, as I have it set for max steam power. I'm envisioning a scenario where I'd be entertaining a bunch of people lining up for milk drinks. At some point I'd run out of steam, right? But when?

I just conducted a very unscientific test where I simulated steaming 12 oz of milk, which would be enough for four 6 oz caps or two 10 to 12 oz latte's. Here's what I did: I used cold tap water (56°), and heated it to 140°. Of course I understand that milk would generally be around 40° from the fridge, but I can't imagine taking more than a few seconds to make up the difference. It took 60 seconds to get the water up to 140°, a temp slightly higher than the 137° I usually always nail when doing by feel (a few seconds past too-hot-to-touch). I immediately dumped the water, refilled up to the 12 oz line, and did it again. After each round I heard the dedicated steam boiler pump* running for a few seconds to add water. I did this 12 times back to back (!) before I decided that continuing would be too OCD even for me. FWIW, the water res level only went down approx. 1/4".

In the real world, no matter how fast you worked, you'd obviously have signifcantly longer breaks between steaming rounds when making non-stop back to back drinks. My down time was approx. 12 seconds per round; I was racing to get the next one started in order to minimize recovery time. That translates to forty eight 6 oz caps. Even if you discounted a bunch of them due to the temp difference between tap water and fridge milk, that's still quite a lot! I'd love to hear detailed, real-world stories of running out of steam power using this machine in a home setting. I'm frankly having a hard time believing it based on my experiment.


*This killer feature means you'll never have a shot in-progress affected by water being diverted to the boiler.

DaveB wrote:! I'd love to hear detailed, real-world stories of running out of steam power using this machine in a home setting.

When I'm serving a crowd, the main gating factor is brewing recovery time under load, not the steam boiler for anything but "Big Gulp" lattes. Most espresso machines deal with 3-4 drinks in succession fairly well. More than that and tricks like preheating the incoming water lead to brew temperature overshoots. Of course, my observation is equipment specific.

Realistically, recovery time is a non-issue for the majority of home baristas as one drink every 90 seconds is more than fast enough.

I do this every year for thanksgiving with mostly milk drinks. I'll take notes next week and let you know...