In my Instant Pot FAQ, I have the following question:
Q: What about natural pressure release? When the Instant Pot finishes cooking, it switches to Warming mode - is that OK with a natural pressure release? Or should I cancel it?
A: Cancel warming mode to speed up natural pressure release.
I was reading the Instant Pot Community Facebook group, and saw a heated debate: Keep Warm and Natural Pressure Release. One side was strongly in the "warming mode doesn't matter" camp, the other was in the "turn warming mode off" group - and used my FAQ post as evidence.
After reading the debate, I started to wonder - am I wrong about warming mode? I assumed that turning off the heat would speed up the natural release - that the pot would lose heat quicker without any heat being added by warming mode.1 The argument against cancelling Keep Warm mode is the pot's thermostat. Warming mode keeps the temperature between 145°F and 172°F, so it won't turn the heat on until the temperature drops to 145°F. That's well below the temperature where pressure will release.
I ran a quick test - I set my IP-Duo and IP-Smart next to each other on the counter, added a quart of water to each, set them for 3 minutes of high pressure cooking, and waited for it to finish. They both came up to pressure and counted down the three minutes at about the same time. I cancelled the Keep Warm mode on the IP-Smart, and waited for the pressure indicators to drop. Much to my surprise, the IP-Duo finished manual pressure release about five minutes before the IP-Smart!
But…is that a valid test? Maybe there is something about the IP-Smart that slows down cooling. To reduce the variables, I ran the test over and over again with my IP-Duo, a quart of water at high pressure for 3 minutes, and alternated leaving Keep Warm mode on and off.
Sitting and watching natural pressure release is only slightly less interesting than watching grass grow. So, instead of babysitting each run, I set my Phone on a tripod and filmed it using time-lapse video mode. Here are the time-lapse videos from the third run, side by side:
You can see them finish within a minute of each other - this is consistent across all the tests. Sometimes Keep Warm mode finishes first, sometimes cancelling it does - but the difference between them was always less than a minute, and it kept moving around as to which was faster. 2
In summary...
Keep Warm mode doesn't affect natural pressure release. It finishes at about the same time either way, so don't bother canceling it. I was wrong in my Instant Pot FAQ; I'm sorry I gave you bad information. (And, of course, I updated the FAQ to match this new info.)
Kaly says
Thank you so much! And really for posting the result right away so I didn't have to read everything (although I ended up skimming anyway).
Terri White says
I thought you’d like to know, 7 years later, this answer is still relevant. I’m brand new to Instant Pot. I have the Duo Crisp and the product guide does not show this detail, nor do any of the recipes address this question. Thank you for the information!
Mike Vrobel says
You’re welcome!
Jdub says
Love this post and video! Answered exactly what I wanted to know, AND with a rousing soundtrack
Butch Dale says
thanks for posting this. We have had our IP for about two years and I finally started really using it. (found a place for it in the kitchen; more convenient to use now) I have been turning off the 'keep warm' for natural pressure release thinking I should(?) but now I realize that the guy who made the IP probably had a reason for it, so now it will stay on.
Mike Vrobel says
You're welcome!
Paula says
This is awesome. The scientist in me totally loves your methods. The busy mom in me appreciates the lengths you went to give us all a definite answer. Thanks!
Crystal says
This is the best possible answer I ever could have asked for for this question. Thank you.
Susan Guerra says
Mike, you simply made my life a bit easier. Thank you.
Mike Vrobel says
You’re welcome!
Aja Gubler says
Thank you for taking the time to figure this out for me! It is frustrating that the instruction manual is not more specific.
Amy Bean says
Wow-this was a super-helpful post and I really appreciate your approach and sharing the results with everyone. I agree with previous poster that the IP instruction manuals are woefully lacking in specificity. Thanks a bunch.
Ckost says
Every time my recipe calls for natural release, after the pressure cooker is done it just turns off. The pressure release countdown never turns on at all. Doesn’t turn to warm mode, just shuts off entirely. I even watched it for 10 min and nothing happened. Am I missing something? Is the pressure release happening, just not the count down? Help? 😂
Mike Vrobel says
What kind of pressure cooker? Make and model?