If you have ever thought about a coffee syphon, you may think they cost thousands of dollars if they are worth anything at all. Here at Northwest Glass, we pride ourselves on providing economical solutions for these amazing items... check out what coffee geek has to say about syphons:
"Once the siphon coffee maker is assembled, heat is applied to the lower container. As it heats up, some of the water is converted to a gas - water vapour. A gas occupies a lot more space than its liquid or solid variant, and it can expand as more heat is applied. Gas can be compressed, but only to a point, whereas liquids do not compress. The water vapour continues to expand and it seeks some relief from all the compression it's starting to have. The only escape route out of the bottom vessel is the siphon tube traveling up to the top, but the problem is, there's a lot of liquid blocking its way. So what does the gas vapour do? It pushes the water up the siphon tube!
This is how the brewing water "defies gravity" and gets up top past the installed filter and starts saturating the coffee grounds. Heated (though not boiling) water will continue to force itself up the siphon tube until the vapour gas in the bottom vessel can have direct access to the siphon. By design, all vacuum coffee makers do not have siphons that sit flush with the bottom vessel: there's always a couple of millimetres of clearance (or more). This leaves some water in the bottom vessel which serves two purposes - protects the glass (if it boiled dry, glass would superheat and could crack), and has a continuing source of water to turn into - you guessed it - more steam, vapour, gas!"
