We all know that coolers can keep things cold. They can hold ice for days at a time and keep your drinks at a nice refreshing temperature. But can you use a cooler to keep things hot?
Does the insulation also work to keep the warmth in and how long can they keep things hot for?
While coolers are primarily designed to keep things cold you can also use them to keep things hot. The insulation works to trap the heat inside the cooler keeping your food warm. For better results wrap your food in aluminium foil and towels.
Coolers can be a great way to keep your lunch hot at work or to keep food warm on a long road trip.
Your food will slowly decrease in temperature over time, coolers aren't perfect at trapping heat. But it will keep it much much warmer than if you just left your food out in the open or didn't insulate it in any way.
Why Does a Cooler Keep Things Hot?
We think of coolers as a device that is able to keep things cold and while this is true this isn't the full story.
Coolers have insulation which works to stop heat transfer. It stops the heat moving through the walls of a cooler.
When trying to keep ice this means it stops the heat from the warm outside getting into the cooler. But it also work in the opposite direction.
When you have hot items in your cooler the thick insulating walls stop that heat escaping the cooler to the cooler outside air. This means the inside of the heater warms up and keeps your food warm for longer.
For even better results wrap your food or layer the inside of your cooler with aluminium foil. Aluminium foil reflects back infrared (or heat radiation) which is something most coolers aren't designed to do. This will trap more heat than usual keeping your food hotter for longer.
How To Keep Things Hot In a Cooler For Longer
Just placing warm food or a warm item in your cool will keep it warmer than if you didn't use a cooler at all, but depending on the size of your cooler vs the size of your food it might not work as well as you would like.
However, there are some clever ways you can keep your items hotter a lot longer. Use one or multiple of these methods to keep things hot for as long as possible.
PLEASE NOTE: Keeping food warm for extended periods of time comes with increased risk of bacterial growth which can make you sick. Refer to your local health authorities about how long you can reasonably keep food warm for before it becomes unsafe.
Wrap Your Food In Alfoil
Aluminium is one of the best reflectors of infrared heat (or heat radiation). This is a form of heat transfer most coolers aren't designed to stop. Learn more about aluminium as an insulator.
Aluminium foil is also widely available and most people have some in their house.
Before placing your food in the cooler wrap it in alfoil to stop this radiant heat escaping. Wrapping it in multiple layers increases the insulating ability.
Wrapping your food in alfoil also stops evaporation of water which removes a lot of heat from your food, so that also keeps it warm longer.
You can also layer the inside of your cooler with aluminium foil if you are aiming to keep a large amount of food warm.
Wrap It All In a Towel
Empty air space is the enemy of keeping food warm. A towel is an insulator keeping the heat in but it also stops outside air getting to your food.
Coolers also aren't made for extreme heats over about 180°F (82°C). Exposure to higher temperatures than that can cause warping in the plastic or damage to the insulation. Read more about boiling water in a cooler.
A towel both insulates your food AND insulates your cooler from the high-heats of your food, decreasing the chances of damage/warping to your cooler.
Pre-Heat Your Cooler With Warm Water
Imagine putting your warm food in a fridge that was just turned off. It'll make your food colder faster right?
Now imagine putting your warm food inside an oven that was just turned off.
Even though both the fridge and oven are turned off the residual heat either keeps your food warm or makes it go colder faster.
The same is true for your cooler. A cold or room temperature cooler will suck heat from your items cooler them down faster.
However, if you fill up your cooler with warm water (from the tap, not boiling) and leave that to sit for 30 or so minutes before you put your items in your cooler the warm cooler will work to keep your items hot for longer.
For Longer Heat: Use Heated Bricks, Heat Packs or a Hot Water Bottle
If you want to keep something hot for an extremely long period of time, or your food is light and won't maintain heat itself, then you'll want to add an external source of heat in order to keep everything warm.
Cover a brick or large rock in aluminium foil and place in the oven to warm up. Then remove them from the oven and wrap them in towels (to protect your cooler from the extreme heat) before placing them in your cooler.
The bricks will give off a lot of heat over an extended period of time and keep the entire cooler warm.
Alternatively you can use heat packs that you heat in the microwave or, my favorite, hot water bottles filled with boiling water and wrapped in a towel.
Hot water bottles with boiling water are easy to fill up, make no mess and when wrapped in a towel or some other insulating sleeve shouldn't warp your cooler.
Hot water bottles can also stay hot for an extremely long period of time, especially when put inside an insulating cooler.
Plus most people have a hot water bottle lying around they can use.
It's a great method to keep things hot in your cooler all day long.
How Long Can You Keep Food Hot In a Cooler?
How long you can keep food hot in a cooler depends on the size and density of the food, the size and quality of the cooler, outside conditions as well as any external heat sources you add into the cooler.
A lightweight item wrapped in alfoil might only stay hot in a cooler for 1-2 hours but a larger and denser food item (like a soup or a stew) can stay hot from the morning all the way until dinner time.
Especially if you use the methods mentioned above and wrap your food in aluminium foil, towels and then add an external heat source like a hot water bottle you can easily keep food hot all day long.
Again you need to be careful of keeping food hot for extended periods of time due to bacterial growth. Be smart and stay safe.
Will a Styrofoam Cooler Keep Food Hot?
Styrofoam coolers can be a great solution for keeping food hot. The insulation works to stop heat escaping, for best results wrap your food in aluminium foil and fill any air space in the cooler with towels.
Given styrofoam coolers are both cheap, lightweight and come in many different sizes from small to large they can be a great way to keep things hot during transportation or shipping.
Best Coolers For Keeping Things Warm
As it goes, coolers that are better at holding ice also happen to be better at trapping heat and keeping things warm.
So this list of the best coolers for holding ice will also give you a list of the best coolers for keeping things warm.
But that list has a lot of different coolers and most of them are quite expensive. Below is a short list of a couple of good coolers I personally recommend for keeping things warm.
Extreme Performance: Yeti Series V
If you're looking for the absolute best performance without compromise then the Yeti V series is the #1 cooler from the job.
It is extremely sophisticated and features the vacuum sealed insulation that you see in similar tumblers or insulated bottles.
It can keep ice 50% longer than any other Yeti cooler at it can keep food hot longer than any other cooler on the market.
It's got a cool retro look but it's technology is state of the art. It's also the most expensive cooler in existence too. You'll be shocked at the price.
Value-For-Money: Lifetime Coolers
Lifetime coolers have the durability, performance and ice retention of some of the best coolers on the market, but they sell for a fraction of the price.
Where other coolers cost you $300+ a Lifetime cooler will likely cost you less than $100.
These coolers are made in the USA, are bear proof and lockable and can keep food warm much longer than a cheap regular cooler.
When it comes to affordability and value for money there is no other cooler I would personally recommend over the Lifetime cooler.
Best Budget Option: Coleman Xtreme
If you're just looking for the best and most affordable cooler in order to keep things hot then I would recommend the Coleman Xtreme.
It's a budget cooler (generally under $50 for a lot of sizes) but it's a big step up from a cheap and nasty cooler you would buy from your local Walmart or hardware store.
It can keep ice for 5+ days and while not as good as the Yeti or the Lifetime it's still pretty decent.
This means it'll also keep food warm for an extended period of time time.
It uses a lighter weight insulation so it's much easier to carry around too which can be a bonus. I personally own one of these and love it.