I can get this engine to run for just over an hour with boiling water in an insulated coffee mug. In a regular mug, boiling water will power it for about 30 minutes. I haven't had much luck with trying to get it to run with ice, yet. It's fun experimenting with it and kids are mystified by it.
Best desk toy ever. My Daughter and Son in law got me this for Fathers Day. Wow! So much fun! The perfect instructional science desk toy!
I am a 71 year old scientist with multiple graduate degrees in chemistry, biochemistry and pharmaceutical chemistry and this is the best toy I have ever received since my first chemistry set and Erector sets when I was 5 yeas old. The engine is beautifully made - it is as much a piece of art as it is a working demonstration of entropy.