While doing a lot of testing, we noticed a problem: all of the induction hobs were slower than we’d expected and even slower than gas cooking. So, what was going on? Turns out it was the pans that we were using. If you’ve got an induction hob that’s taking more than five minutes to boil a pan of water, the cookware you’re using could be at fault.
Induction compatibility doesn’t mean the best performance
For a pan to work on an induction hob, it needs to be magnetic. This is because induction hobs use coils of copper wire to create a magnetic field. When a magnetic pan makes contact with the hub, this magnetic field causes the pan itself to heat up. That’s great news for efficiency, as little heat is lost externally, and it also means that cookware responds fast to power changes made on the hob. Of course, the downside is that for an induction hob, you need to have compatible pans: ceramic, aluminium and copper pans will not work. Many premium pan manufacturers get around the problem by casting the pan in a non-magnetic material, but using a magnetic base. This base may be easy to spot, or it can be integrated into the pan and not on show. Using a base like this makes a pan compatible with an induction hob, but it doesn’t mean you’ll get the best performance.
Power usage is important
All induction hobs will have a specs document that tells you the maximum power each coil can produce, such as 3000W. This maximum figure depends on the size of the pan that’s used (this is why you should match the pan size to the burner size), but it also depends on the construction of the pan, as we found out. Using anodized aluminium cookware with an induction-compatible base, we noticed that water took a long time to boil, regardless of the hob we used. We checked the cabling we used to wire in the hobs, and had an electrician upgrade the cable from the consumer unit, checking the voltage of the connection, and everything checked out. Investigating further, we wired our test induction hob into a standard 13A plug, and connected this to a power meter to see what was going on. Don’t do this at home: we deliberately only used a single burner and one where the maximum power would not exceed 3kW (the maximum power through a 13A mains plug). Using the anodised pan, we saw a power draw of 728.8W, which is massively under what a general hob can consume and a far way off even a slow kettle. We switched and used a bog-standard stainless steel pan, which is fully magnetic. On the same hob using the same burner, power consumption jumped to 2363W, which is three times the power draw. This made a huge difference to pan heat-up and boiling speeds, delivering the kind of performance that we’d expect from an induction hob. Clearly, having a fully magnetic pan means that the induction hob can use its full power; with a magnetic base only, an induction hob’s power is limited. We repeated the tests using several brands of anodised pans and got the same slow results each time.
You can still cook with all induction pans
The main difference that pans make is in how quickly they can heat up. Using the anodised pans, we found that we could still fry foods and could still boil water, just everything was much slower than when using stainless steel instead. As a guide for testing at home, a medium-sized pan filled with 1-litre of water should take around four minutes to get to 90°C, so less than five minutes for a full boil. If your hob is taking significantly longer than this, it could well be the cookware. Try repeating the test with a stainless steel pan (borrow one if you don’t have one). If the boiling test rapidly improves, you know your cookware is hampering your hob’s performance.
