Oh, the dreaded OvHt code. OvHt is the Instant Pot’s Overheat code – and is both a blessing and a curse as I develop recipes for the Instant Pot. From the InstantPot.com “Questions after your purchase”:
This mechanism is called “burn-protection”. When a high temperature (140C or 284F) is detected at the bottom of the inner pot, the burn-protection mechanism suspends heating to avoid burning food. On Instant Pot IP-DUO series, a warning message “ovHt” is flashed on the display.
Instant Pot Questions After Purchase – InstantPot.com
The Overheat blessing: it saves dinners. The sensors in the pot notice food sticking to the bottom – it starts to overheat – and turns off the power right when I’m about to burn something. In the old days of stovetop pressure cooking, I wouldn’t get Overheat mode – I’d get a layer of burnt food on the bottom of the pot. I didn’t have a digital brain in my cooker, warning me that a disaster was about to happen.
Unfortunately, burnt food is the nature of pressure cookers. Once the lid is locked, the food can’t be stirred to even out the heat. If there is a thick layer of food on the bottom of the pot, and it heats up faster than the food on top, it can burn. Especially tomatoes, or starchy foods like rice. Lorna Sass’s Cooking Under Pressure taught me to float tomatoes on top of the other ingredients – if they are stirred in, they’ll sink to the bottom and scorch. And, about starch…like my Jambalaya recipe from Tuesday…Instant Pot specifically warns:
This “burn-protection” mechanism works very well, except if the food has very high starch content. For example, if you add flour in your chili recipe, the flour sinks to the bottom, solidifies at low temperatures and can block heat dissipation.
Instant Pot Questions After Purchase – InstantPot.com
The Jambalaya rice (with tomatoes! Extra danger!) was definitely sinking to the bottom and starting to burn before the rest of the pot could heat up enough to start pressure cooking.
A related problem is a big batch of a thick recipe. Like, say, a big batch of chili that fills the pot to the max fill line. The ingredients are too thick, and heat builds up on the bottom of the pot before the top starts to boil and bring the pot up to pressure. Again, the result is overheat mode.
Is the pot about to explode?
Relax, it will be fine. (Everyone’s first worry – the pressure cooker is about to explode.) This is the opposite problem – before it can even come up to pressure, it is overheating, and the digital brain in the Instant Pot turned off the heat. (Now, I’ve never had an overheat code after the pot comes up to pressure, but to be on the safe side, make sure the lid is not locked. If it is locked, the pot is pressurized. Quick release the pressure and wait for the lid to unlock before continuing. But, almost all the time, overheat will happen before the pot can pressurize, and you can open it safely.)
Why do you know so much about overheat mode?
Um…well…because I keep pushing my pot to the edge of overheating. The pressure cooker is a sealed pot that traps steam to build pressure. Sealed pot equals no evaporation in a pressure cooker. Recipes that would normally thicken up over long cooking times in a traditional pot – like chili and stew – tend to come out watery from the pressure cooker. To avoid runny chili, I cut way back on the liquid in my recipes…and sometimes, I don’t get that balance right. The result? OvHt.
What do you do about overheat mode?
When my pot flashes the OvHt signal, it is telling me there is a thick layer of food stuck to the bottom of the pot, and it is very close to burning.
The first thing is to un-stick the food. I remove the lid and scrape the bottom of the pot with a flat edged wooden spoon. Since the pot is full, I can’t see the stuck food. But I can definitely feel stuck to the bottom of the pot – as I scrape the wooden spoon, the bottom feels bumpy and rough. Once I have cleaned the pot, the bottom will feel smooth. (This is why I love flat edged wooden spoons so much – they transfer the rough feel of the stuck food up to my hand.) Scraping the rough, overheating food can take some elbow grease. Sometimes it is really stuck on there.1
I keep working it, scraping, spinning the pan, scraping at different angles. Don’t give up – it might take a while, but eventually the rough feeling will go away, and the bottom of the pot will be clean. If I can scrape the entire bottom of the pot, paying close attention to the edges, and the whole thing feels smooth, then I’m ready to move on to the next step trying to prevent the sticking.
The second thing is to increase the amount of liquid in the pot. We want enough liquid that the whole thing heats up and starts to boil before the bottom layer sticks. I add more water or broth, depending on the recipe – at least two cups – lock the lid, and try to start pressure cooking again. If it overheats again, I repeat the whole process – scrape the bottom clean, add two more cups of liquid, and try to pressure cook again. Eventually, I’ll get the right amount of liquid in the pot for it to come up to pressure before it starts to burn.
Once it comes up to pressure I’m past the danger zone – it’s only in the building pressure zone that I get overheating. When it is actually pressure cooking, funnily enough, there’s a lot less heat on the bottom of the pot. The heating element on the bottom of the pot is on high to bring it up to pressure. Once it is at pressure, it cycles the power on and off to maintain that pressure – and this means a lot more even heat, and less chance of burning on the bottom.
What do you think?
Questions? Other ideas? Worst-sticking recipe you’ve ever had? Talk about it in the comments section below.
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