PowerSaving

Saving Power at Home & Work

Induction Hob

We decided to conduct a quick test to see how efficient an induction hob was in comparison to a conventional electric stove/hob.

water_measureThe test was very simple.  We measured out and boiled exactly one litre of water, using the same pot on each type of stove.  We measured the power consumption of each, as well as the time taken for the water to boil.  We then multiplied the average power consumption by the time taken to boil, to get the energy consumed and then compared the values to determine the efficiency (or not) of the induction hob.

In both cases the water was taken directly from the cold water tap, within a few minutes of each other,  and the pot, water and stove started at the same normal room temperature each time.

Conventional Electric Stove

pot_on_stoveWe measured out exactly 1 litre and poured that into the pot on the stove.  The stove plate was switched on to full power, and the stop watch was simultaneously started.

In the meanwhile a clamp meter, that could measure power, was attached onto the stove wire in the DB board, to monitor the power consumed .  The initial power reading was 1.43kW.

stove_reading1We waited for the water to boil.

As the water got close to boiling we re-checked the power and noticed that the reading had dropped down to a lower value of 1.358kW.

stove_reading2We judged the water to be boiling when the surface just started to become violently agitated.

stove_timeThe time taken to boil was  7 minutes 23.46 seconds.  In decimal format that is 7.391 minutes, which in turn is 0.1232 hours.

So using the average of the two power readings, which is 1.394kW, we get an energy consumption of 0.1717kWh, for the conventional stove to boil one litre of water  (by multiplying the average power consumption by the time).

Induction Hob

The pot was cooled down by emptying it, and then allowing cold tap water to flow over it until it was completely cold to the touch.  It was then dried and allowed to stand for a few minutes, to ensure that it was definitely back to room temperature.

inductionpot
We then measured out exactly 1 litre of cold tap water, poured that into the pot and put that onto the induction hob.   The hob was switched on and the stop watch was simultaneously started.  The hob was dialed rapidly up to full power.

Its always amazing to see the bubbles form in the water almost immediately!

In the meanwhile we had reattached our power meter to a cable supplying power to the hob.  The initial reading was 1.419kW.

induction_reading1

 We waited for the water to boil and took another power reading when we could see the water was close to boiling, as before.

induction_reading2

 The second reading wasn’t that different in this case.

When the surface of the water just started to become violently agitated (we actually waited a second or two to be sure), we stopped the stop watch.

induction_timeThe time taken was 4 minutes and 52.82 seconds which is 4.8803 minutes, which is 0.0813 hours.

The average of the two power readings was 1.423kW, which yields an energy consumption by the induction hob of 0.1157kWh to boil one litre of water.

Results

So according to this test, the conventional stove used 0.1717kWh to boil one litre of water while the induction hob used 0.1157kWh to boil the same amount of water in the same pot.  That represents a saving in energy of 33%!

26 thoughts on “Induction Hob

  1. Verry interesting – great website. Where can one purchase these induction hobs and waht about installation cos?

    Any other info on cost savings and ways to reduce my carbon foot print will be appreciated. I hope to be building a house within the next 6 months

    1. Hi Ian

      You can get small, cheap single plate induction hobs from Makro, Outdoor Warehouse, Builders Warehouse etc.

      You can get multi-plate counter-top induction hobs from most kitchen appliance stores.

      Installation of the counter top hob is easy you can either do it yourself or get an electrician if necessary.

      Hope that helps.

      1. A small thing to remember is conventional pots and pans do not function on the induction hob.
        If like my home, you may need to replace cooking ware at a considerable cost namely AMC.
        An error on our part when we did the change over.

  2. Hi

    You didn’t perhaps also do the test based on gas and ceramic? Would be interesting to see how close gas and ceramic is to induction.

    Regards

    1. Hi Marie

      Unfortunately we haven’t done that test yet.

      My guess would be that gas would be a lot less efficient. Simply because you can feel heat in the air when cook with gas, which you don’t feel with induction or even a conventional electric stove.

      Any heat you feel is wasted energy, because that is heat that is not going into the pot.

    2. Great. Was wondering wheter you guys can test whether gaa stoves are really cheaper than induction hons. The cost of electricity vs cost of gas used.

  3. any chance you could compare this to a kettle? Also, come on guys – maybe a thermometer in pan not just ‘it looks agitated’ 😀

    We’ll have to get you a homebug to monitor both the consumption and the temperature!

  4. There is a great misconception about the pots and pans needed for an induction hob. Our standard cheap Pick n Pay pots work very well.

  5. Hi,
    I am using gas hob now, I am just bought the new house and will move in next few months and I thinking to use the ceramic or induction cooker;
    could i know which one is better, less power consumption and no radiation.
    what is the power consumption between ceramic and induction cooker?
    Thank you.

    KONG

    1. It comes down to how much of the energy coming in though the electricity wires reaches the food you are trying to heat. In other words you are trying to minimise heat (which is exactly the same thing as energy), being lost to other parts of the system.

      Induction hobs heat the surface of the pot directly, by inducing eddy currents in the metal. So I would expect the least amount of heat to be lost in useless forms in that process. For example, when you switch the induction hob off after cooking, the surface of the hob is quite cool, while the surface of the ceramic hob will burn you for quite a long time afterwards – that’s an example of wasted heat.

      1. that is not so residual heat is stored in the glass cooking surface of an induction hob and can burn you. I have had good results from our induction cooker and power savings over conventional ovens are remarkable but they will still burn you!

  6. I am glad to find your website.

    I experienced these stoves whilst on holiday in Switzerland and they are absolutely wonderful. The instant heat caught me off guard and supper was burnt a couple of times! Will I have one here in SA, YES.YES YES.

    No waiting for a burner to heat up saves time and is much less frustrating besides the saving of energy. I wish I had one when my children were in school.

    Now since I found a store I am definitely going to have a look at my finances and in my husband’s wallet!

    I am glad to see that induction geysers are alo available.

  7. Good day.
    I am also very interested in what the results would be from a standard kettle vs kettle boiled on the induction cooker. Also thank you for the magnet test, because I am struggling to find “cost-effective” pots and pans.

  8. Hi
    I suggest a longer test , boiling potatoes or making pasta to get a result over a longer period.
    This will give a more accurate power saving result. I am toying with the idea of an induction hob instead of my old plate hob.

  9. Hi
    I did a test on my kettle and looking at my prepaid meter it used 180 watts to boil .
    This is the same as the electric hob used in the test above. In the short term the induction hob is faster. A new house yes , retrofit because of savings , no.
    I want to see a test done over a longer period to get a more accurate result when cooking.
    Safety wise the induction wins hands down. I have been looking at solar panels (PV), but until they design cheaper and longer lasting batteries you will not save money as a private
    home owner . Forget what the people selling the products tell you.
    For a business it is different ad it is tax deductable and when downtime is involved it makes
    sense. I have a small inverter with 3 batteries that gives me security when needed.
    I also have a generator on standby.

    1. Hi Leon
      Thanks for the info. I assume you mean 180 Watt-hours (Wh)? Which is 0.18kWh which compares with the numbers we got in our test. I also assume you boiled 1 liter of water?

      The only unknowns then preventing a direct comparison is the starting room temperature and the altitude (our test was done in Johannesburg at 1600m above sea level which reduces the boiling temp of water). If you have an induction hob, try comparing the energy consumed boiling one litre of water in a kettle vs a pot on the hob, both starting from the same room temperature (ie. just pour cold water into the kettle and the pot from the same source at the same time). That should give you a good estimate of any savings.

      Lastly regarding longer term tests, I don’t think they are necessary because it takes the same amount of energy to boil water starting from the same temperature. So the above test very effectively isolates the wasted energy using any given cooking method, because any differences in energy used to boil the same amount of water starting from the same temperature must be wasted energy.

      1. Hi
        Yes .18 kwh is correct , cold water and around 18C and sea level. I live in Wilderness outside George, and have seen induction hobs demonstrated .
        but I do not own one . I still use the old solid plates on my old stove . What I was
        referring to was looking at your meters and power used in the short term for water it
        saves money but once the temperature is at the required temperature it will most
        probally be a different figure when cooking food . I have never done other tests and
        would like to see real conditions used to get an accurate figure . It will be interesting to see what the tests reveal.

        1. The efficiency test above should be accurate because it identifies wasted energy that does not reach whatever is in the pot, using a normal stove. This will apply regardless what is in the pot, and how long you cook for.

  10. We have an induction hob and apart from being much more efficient, it is so easy to keep clean, almost like new. The only drawback is that most of your own pots and pans won’t work as theyou need to be a metal that a magnet will stick to. But having said that is proberly is about time you bought new ones.

  11. I have had my induction cooker for just under 10 years and would never, ever go back to the traditional electric or gas. It is fast, efficient and economical and exact. When I go on holiday my cooker is the thing I miss most. I highly recommend induction.

  12. KEEP IN MIND: The above mentioned exercise proves energy efficient when boiling water, as the water took less time to boil due to high energy conversion rate. When cooking eg a stew however will decrease the difference in energy consumption between the resistive plate and the induction plate, which might make the purchase not worth your while…..unless you will only be boiling water & eggs

  13. Hi Guys iv compared two Siemens products one being ceramic glass base (iq500) and (iq700) induction.
    The simple tech spec has the ceramic hob at 2.3 KW and the induction 3.7KW. other than the speed at which it heats how can this be efficient specially if you are planning solar and battery storage.

  14. Hi.. I find your site very interesting. Can you please assist or advise if it’s possible to use a hob and oven of different brands or hob and oven of different series?

  15. Cnappy Chef sells a little plate that allows you to use all pots on the induction stove. I found that a week after replacing a set of pots! Check first, before you go pot-shopping!

  16. It is possible if the oven and hob have their own switches. In my case the hob has no switches and all the switches are on the oven, and they are of the same brand for ease of connectivity.

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