OK, I finally caved in and bought the £20 vacuum pot from ebay, and I need some advice from the syphon-meisters in here!
Used it twice, once last night and once today. Last night I was terrified of cracking it by heating too suddenly, or blowing the whole thing sky-high (blame
this dude whose brewing guide I followed, he says that if the water in the bottom bulb gets too hot it might explode). Miraculously none of that happened, everything went well and the coffee tasted ok. (For what it was - I had used cheap Sainsburys coffee to practice with cause I didn't want to ruin the good stuff!
)
Used it again about an hour ago, and even though I did everything the same way or at least thought I did it couldn't have gone more wrong!
Firstly, as soon as half the water from the bottom bulb rose to the top, it would fall again. Took a couple of efforts for me to realize that it was because the bubbling was forcing the rubber seal between the two open and the pressure was being let out. So I pressed the top bulb down tighter (against the Intelligentsia guy's advice in the video), and third time I managed to get the water to stay up. Added the grounds, stirred, waited 45" or so, stirred again, removed the heat, and it started dropping, except for one thing: the pressure of the rising water had dislodged the filter, and the grounds were falling through along with the coffee! Ended up with half a litre of mud essentially.
Now, I don't know what went wrong. My first thought was maybe I had overheated the water before sealing the top bulb into place, and hence the pressure of it rising too forcefully dislodged the filter. So you know, in the interests of science I had to test it out!
Since I hadn't used a thermometer during the brewing I couldn't know it for sure (got a digital probe somewhere, but I can't find part of it!), so I decided to taste the coffee instead! I know the taste of overbrewed/boiled coffee VERY well, so I decided my mouth is a more reliable sensor than any thermometer!
So I filter the muddy gunk through my Aeropress and have a sip, and nope, surprisingly enough it kinda tastes allright! Don't know if it's as good as it was meant to be (I was using different beans than I used yesterday, the last of a bag of Zamorana I bought from Hasbean last week, so I don't know what it's supposed to taste like with this particular brew method done perfectly), but it didn't taste as if it had been boiled.
So now I don't know, it doesn't seem like the water was too hot, so I have no idea what I did wrong anymore! Can anyone make any suggestions?