You're ready to spend money. Just buy the right thing.
You've plainly stated that you're ready to spend $30+++ on various apparatus to try to solve this. The money you're willing to spend is much more than a proper humidifier actually costs. So just buy one of those. If you can't bear to spend $30, then go to the Salvation Army store and spend $5.
If you don't like misting humidifiers, there are lots of other kinds. Misting has the advantage of a very sensible power draw, because it's not heating the water, it's letting your house's normal furnace do that more efficiently.
This is a firestarter at so many levels
NEC 110.3(B) says you must obey equipment's labeling and instructions. An Instant Pot is a kitchen appliance, specifically a pressure cooker with computer controls. It does many things, but humidifying is not one of them. It is not labeled for that, which means UL didn't test for that, which means it's not a safe appliance for that purpose.
What happens when it runs dry is a case in point. Instant Pots aren't designed to run dry where they would go into thermal runaway. There is no conceivable listed use of an Instant Pot where it would ever run dry, since operations are supposed to be on a timer or monitor. You are defeating those features to make it possible to misuse.
Further, it is a kitchen appliance designed to be used exclusively on kitchen countertops. It is not designed to be in bedrooms, set on furniture or floors where it has a chance of being knocked over. It has no anti-tip features like real humidifiers do. It is not designed to work on carpet or with magazines, papers or dust bunnies underneath.
God help you if you splash a pot of boiling water onto your feet! Seriously, you could find yourself in the hospital getting skin grafts. Scalding is serious business.
It is designed to be used in kitchens where GFCI protection is provided, which is not found in bedrooms generally. Get it? You have a water appliance with no GFCI protection in sight. What's wrong with this picture?
It comes with a 2 foot cord, which is appropriate for kitchen countertops where all points are within 2' of a socket. Anywhere else, it's at high risk for being used with an extension cord, which it is not listed for, and should not be done given its very high power draw. It has much more power draw than an air conditioner. So you'd get one of those burly 12 AWG extension cords for an air conditioner, right? I bet your Instant Pot is plugged into a run-of-the-mill 16/18 AWG cord right now. Whoops!
It's this kind of stuff that gets you in trouble. It can also get your insurance voided or significantly reduce your claim, since you are doing something you should not.
The Instant Pot already has a shutoff feature
Because the latent heat of vaporization is not a surprise.
And the Instant Pot has a timer and a known rate of heating.
- You already know (or reasonably should know) the electric power consumption of your Instant Pot. Yours will say, but my guess is 1500 watts, because that is the maximum allowed for a plug-in kitchen appliance under UL listing rules.
- The latent heat of vaporization of water is 2264.705 joules per gram.
- A joule is 1 watt for 1 second. (wow, that's easy)
- That means that the Instant Pot makes 1500* joules per second
* Your value actually goes here.
Now you can compute: in my example it takes 2264 / 1500* = 1.51 seconds for the Instant Pot to boil 1 gram of water.
- 1000 grams makes 1 kilogram.
- 1 litre of water weighs 1 kilogram (not a coincidence)
- A litre is basically a quart (good enough for this).
So 1 litre = 1 quart = 1kg = 1000 grams = 1000 times as long as a gram, so that makes (in my example) 1510 sec. = 25 minutes. Per litre.
So if you have a 10 litre pot, that's 250 minutes or 4:10.
Now you know how to set the timer on the Instant Pot.
This will finish with some water left over, because we're ignoring inefficiency and the specific heat required to raise the water from tap temperature (15C?) to boiling temperature. That is small potatoes compared to latent heat of vaporization, and you need a little safety margin anyway.
Also, you should be dumping out the last 20% of the water, because it has 5 times the mineral concentration of normal water, and if you boil it dry, it will leave mineral deposits on your Instant Pot. That mineral action can actually etch stainless. That's one problem that misting dehumidifiers solve (they throw the minerals into the air).
Honestly, since the Instant Pot is so computerized, I'm amazed they allow any mode where enough joules could be added to evaporate all the water.