Water Kettle Efficiency Test

Hi everyone, I made this Instructable in order to find out which amount of water is perfect for this kettle. I bought this kettle from Philips and normally I heat 250-500ml of water in it. Recently I also acquired a power meter for the 220V power outlet, so I combined these two devices into one experiment. Whole experiment was very fun and interesting to do, although it took me much time to make it right.

For this particular experiment, I´ve used:

1x kettle (water heater) from Philips HD4646 rated at 2000-2400W, 220-240V, 50-60Hz

1x Power consumption meter rated at 220-240V, 16A

1x 1 liter measurement cup

1x Digital multimeter, used as Thermometer

Kettle from Philips is really good, it warms the water very fast, and it is easy to operate with. Also it is produced in Poland, which I think is very good, comes with 2 year warranty, and overall quality is pretty good.

Power consumption meter is really good device, because it can measure realtime energy consumption, power, voltage, current, cos fi factor, frequency, lowest and highest power, and it can also calculate energy cost.

I connected the kettle to the power meter and then to the power outlet. I reset my power meter every time I made test, so that I get always true values. I set it up to show energy consumption kWh and time elapsed. I´ve used normal drinking water, which was around 20°C warm, just as the room temperature, perfect for making tests.

I´ve decided that I would make tests with 0.1, 0.2, 0.3, 0.4, 0.5, 0.75, 1.0 and 1.5 liter of water. I measured the exact amount of water with my measurement cup, spill it into the kettle, pushed ON button and that was it. I waited for the kettle to be done. I recorded all the process with my camera, so that I can later check how the values were changed through the time. With 1 liter test I also decided to measure the temperature of the water with my digital multi meter, to see how temperature increased through the heating process.

After every measurement I had to wait approx. 30 minutes for the kettle to cool down to the room temperature and then start another test.

After I finished all the tests I took my recorded video, and from there took all the values and write them in Excel table. It was much easier then to make some points, and I saw immediately that kettle is not good for small amounts of water, but rather for more water in it.

I made some more columns with time/volume and power consumption/volume values, so that I can see the relation between time and increasing volume and between power consumption and increasing volume.

Energy consumption graph showed me that my values rose pretty linear (R2 = 0.9991), but with a narrow angle, meaning that the kettles efficiency rise with the volume.

The second graph showing the temperature increase was surprisingly also pretty linear (R2 = 0.9968), only deviating at bottom and top of the curve.

It was very inspiring for me to make this test, I didn´t really know what to expect as the results from it. Good preparation was here the key. The kettle is the most efficient at its biggest volume. This is due to the fact that heating element consume a decent amount of energy to heat itself up too, and of course the bottom and barrel of the kettle. Now I will know that I should cook more tea at once, and not only one cup at the time. I also noticed that at smaller volumes, I got a lot of watercress. It was very important to record the whole process, so that I could took values later from it.