attofarad - thank you for your helpful response. I tried searching and couldn't find anything authoritative. One website said "around 50 lbs" but that's pretty vague.

So far Thermador hasn't given us any kind of guidance. An unofficial comment was they wouldn't put a 20 qt stockpot on it. 20qts of water weigh around 44 lbs, so with the weight of a pot, it would put it right at 50 lbs. When they finally get a real number back to us, my guess is that they will be conservative to protect themselves.

Cheryl

I don't advise standing on it. Nor banging with a hammer or cast iron pan.

Wow, jadeite - I never thought about this! I was hoping to find something like a 16 qt pot to boil lobsters in, but maybe I better just run two smaller pots - a 12 and an 8, which would not be full anyway. I would think that if the weight were spread out it would be less likely to crack. Thanks for the heads up, though! I'll keep watching for more info.

Ginny - my thoughts exactly! I was all set to use a 20 qt pot on my cooktop when I heard about ceramic cooktops breaking. I think shock is worse than sheer mass, but there has to be a load limit. So far Thermador hasn't been very helpful. If I get a definitive answer, I'll post it. So far it seems that 50 lbs is the limit.

Cheryl

A gallon of water weighs 8.3 lbs so a 5 gallon pot full of water will be 41.5 lbs plus maybe 3 to 5 lbs for the weight of the pot. Remember Archimedes displacement principle when adding anything to the pot.

A 5 gallon (20 quart) pot is pretty huge. Can't really imagine needing one bigger for a lobster boil.

You might be able to find some user experience on the Harvest forum here at GW.
All the cracks I've read about were from impacts.

After many calls, we finally got an unofficial response from Thermador. We were told the cooktop can bear loads up to 200 lbs. I was astonished, but they told us that they can stand on it without breakage. They would not put this in writing because (they said) there is no official number.

I told them that I was going to put a 21 qt pot on it, loaded with canning jars and if it broke, I was going to claim against the warranty. I made sure my husband was part of the conversation. They said to go ahead.

So I did. Very carefully, and with much trepidation. I canned 28 jars in 4 lots over about 4-5 hours. In addition to the canner I also had a 10 qt pot on the cooktop, heating the contents of my canning jars. My guess is the total weight on the cooktop was around 60 lbs. The cooktop is still intact.

I am NOT recommending that everyone with induction can load up their cooktop with impunity. Call the manufacturer if a limit isn't stated anywhere. But I feel a bit better about my unit.

BTW induction does a great job of canning - perfectly uniform heating for hours. And the kitchen wasn't unbearably hot.

Cheryl

Cool!

Thanks for updating!

Thanks, Cheryl! Watch out, lobsters!

Jadeite, are you canning with a pressure canner or a hot water bath? If a pressure canner, what brand? Is it aluminum?

Alex - it's a hot water bath, steel, made by Ball. There is no recommended pressure canner (Presto, All American) that will work on induction. Presto and Fagor make steel pressure cookers which could be used for canning, but neither has been tested or approved by USDA. I think you already knew this!

Cheryl

I did know that but I thought that there might have been a new development on this front. I have read that it MIGHT be possible to use aluminum vessels on an induction top so long as one didn't expect top performance. That was theory rather than someone writing of their own experience. I thought that there might have been a slim chance that you actually put the issue to test. Just checking.

You can use aluminium on induction with an induction plate. I tested this for my own satisfaction, using a carbon steel plate under an aluminium pot. It will work, but the efficiency is drastically reduced. IMO it's not worth it.

I plan to do pressure canning on a propane burner outside. It's a bit of a nuisance, but it will work. May keep me warm in fall and winter too.

Cheryl