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We recently found this old vacuum pot at my grandparents`. It seems to have all the parts needed for brewing, but no separate heater. We didn't dare to put it on a ceramic stove without further knowledge. All we know is it was last used some 40 to 50 years ago. It says "Original Santos" on the side and seems to have capacity for 8 cups. The bottom is flat, and has no burn marks (in case a heater would leave some). We have access to ceramic stove, but is this safe to use on it? Are there any other options, possibly in Do-it-yourself spirit?

Edit: I'm starting a bounty for any precautions I should take if I am to place this old treasure on a ceramic stovetop. Any tricks to make sure it will not explode?

the vacuum pot

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I use this heat diffuser:

http://www.amazon.co.uk/Truka-Large-Stovetop-Double-Diffuser/dp/B000LCNLJY/

to heat my flat-bottomed glass Cona vac pot, on a halogen heat glass hob, which I think is similar enough to a ceramic hob to be relevant.

The diffuser also works to retain the heat, which helps with the process:

  1. Turn on heating element to mid-heat (I use 4/6), with diffuser in place
  2. Heat water to boiling point in kettle (to save time). It's OK to boil, since it won't be at boiling temp when it eventually touches the coffee grounds.
  3. When boiled, pour water into (cold) bottom pot, and place on diffuser
  4. Fit top pot (with coffee grounds)
  5. When water has all gone up into top pot, and bubbling starts, turn off heat, but leave entire pot on diffuser, on heating element
  6. Wait 3 minutes (heat still turned off; diffuser will remain hot enough to keep water in top half
  7. Remove (carefully) whole pot (both parts together) from diffuser - I slide it to a cold area of the hob
  8. It will immediately start to cool, and coffee will return to bottom half
  9. Wait for pressure to equalise (hissing), separate pots, and serve
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+50

Great find! How fun. You do indeed have a vacuum coffee maker -- a.k.a. vac-pot, syphon, or siphon.

This style of vac-pot is intended to be used on a stove-top (specifically: having a flat bottom, and with a handle on the neck of the bottom part -- the "bulb") -- looks a lot like this current model from Bodum - c/o Amazon. There's a good primer on the history and types of vac-pot at WeCraveCoffee with some good pictures.

However, in general, glass pots are generally not recommended on flat glass-ceramic cooktops for a couple of reasons: they can scratch or otherwise damage each other, and the poor conductivity of glass makes glass-on-glass heating less efficient. More info on this from a question on Seasoned Advice, and recommendations from GE Appliances for their own stovetops. I did see some products such as this one that depicted glass vac-pots on glass-ceramic cooktops. If all of the glass is high quality, as should be expected for cookware intended to be used on a stove, it should be able to withstand the temperature changes induced by a cooktop. I (personally) would be comfortable using this vac-pot on a gas flame, but cautious/wary of using it on glass-ceramic cooktop. Glass cookware works well over gas flame, but I have less experience with glass cooktops... your "mileage" may vary.

For a more "DIY" adventure as you suggest, consider a mechanism to suspend the vac-pot over a flame heat source. Other styles of vac-pot (such as this Hario model - c/o Amazon) have a scaffolding that holds the bulb (bottom) and the hopper (top) so the whole apparatus can be suspended over a separate heat source, like an alcohol or butane stove. Check some vac-pot brewing guides that show this type of integrated round-bottom bulb and holder (e.g., from Blue Bottle, Stumptown, CoffeeGeek, and many others). Warning: this may remind you of Chemistry lab from School. ;-) And of course be careful with fire.


Separately, just for completeness...

It also looks like you're missing the filter piece. These are inexpensive (relative to the whole apparatus) and you'll want to purchase a new, compatible one anyway (see also another question on siphon filter replacement).

Another thing you'll want to check is that the rubber seal between the bottom and top parts is still in good shape, especially if this pot hasn't been used in a few decades. This is for reasons both practical (you need a tight seal for the vacuum to work well) and safety (you don't want the seal to come lose and spray boiling-hot water everywhere)!

  • Great info, wish I could upvote more. Thanks for mentioning the filters, I examined the vac-pot and thought the black piece in the center was the filter, since it has a saw-like structure that would allow waterflow while keeping coarse coffee in, but now I know to look for some cloth filters. However, I am still not sure if this answer is a "yes" or "no" for stove top use? :p – milez Jul 26 '15 at 6:29
  • @milez - You can only upvote once, but can accept once also ;-) Now you've got a bounty - you're serious! :) Like I said, personally I wouldn't use glass pots on a glass-ceramic cooktop; it's probably okay if the pot is good quality glass. I asked a follow-up at the cited Seasoned Advice question, but you may wish to ask there also if I don't first :). The concerns are with 1- type of glass (related to thermal expansion -- e.g., borosilicate versus soda-lime), 2- burner size should match the pot (your bulb has a very small base), and 3- mechanical shock (e.g., dropping it; least concern). – hoc_age Jul 28 '15 at 13:55
  • @milez - Also, Bodum (current manufacturer of Santos) has this manual that says that "electric" stove is okay. It seems like a new manual, and it does NOT have any warning against glass-top stoves, so I think this suggests that the manufacturer thinks it's fine to use on glass-top. I can't tell (and see no information) whether the current product is borosilicate or soda-lime. – hoc_age Jul 28 '15 at 14:20
  • I started the bounty because I wanted to see if anyone had any tricks for knowing if it is the right type of glass or heating it safely. But don't worry, the bounty might still be coming your way :p I guess I held back with the answer because it still left me wondering to be or not to be. That said, the manual link is pretty good evidence for electric stove being okay. It is a shame my pot has lost its manual. – milez Jul 28 '15 at 14:28
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This video seems to show the exact same model of vacuum pot being used on a ceramic hob without incident.

https://www.youtube.com/watch?v=dsY3Mj9BEn0

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