Wednesday 15 October 2014

Saving Eskom electricity tarrif cost by using a thermos flask?

Saving you money, saving you time, after a week of trying the air pot method I am sold on the idea just on the time it saves, never mind the money.

This was on my mind a few days back, we save gas on the boat with a thermos pump pot so why not do the same here at home? I have just checked a few web sites, some use a rate of R1.00 per kwh and another uses R1.50, so who is correct? Check Justins take on the subject below.

One issue thats not mentioned is the saving of time, time is money kind of thing and waiting for a kettle to boil cost both the electricty and your time!

Eskom is the South African power utility.

Thanks for those numbers Justin.


Roy it's a good idea - the Thermos is WAY more efficient than a kettle - mostly because one boils approx 2x too much water every time kettle is used.

So I would estimate the saving at about half of the current usage.

Electricity costs about R1.60 per kwh in Cape Town (one unit = 1 kwh). A kettle uses about 1.5 kw. So estimate how long it runs for every day - example if used say 8x per day, 2minutes each, that's 16 minutes. In a month that's 480 minutes, or 8 hours. At 1.5 kw you have 12 kwh. Total cost is 12 x R1.60 = R19.20. Thermos halves the cost approx, the saving is in the order of about R10 per month? I would have expected more..... see if these assumptions fit your case.....

Our kettle and half full, which is about what we boil each time took three mins, two secs, to boil! So the saving will be fifty percent larger?

There is one catch of course, we have the pump pot so the cost right now will be nothing, Jean says we paid R350 for it years back, so what do they cost today? you then need to build the cost of buying one into your sums.


The idea is proving to be a winner, excepting the reaching out for the kettle still continues when we want another cuppa! its far faster using the airpot and even some hours after filling with boiling water we still get a hot drink.

Just in today:

Hi Roy and Justin,

Well, I suppose any saving on mains electricity charges is a worthwhile venture but you would need quite a large and well insulated flask to store the amount of tea we get through every day as we brew a teapot each every time and get two cups each from these.

My largest flask is just one litre unless I count the Air Pot that is quite big but is not completely sealed so would lose heat and as you know the water must be at boiling point to get that proper cup of tea?
For instance in Joburg you never get the kettle to boil at 100 degrees C due to the altitude so you never get a decent cup of tea. Some people have been known to hold the lid on and block the spout to add a little pressure just to get the water to as close to 100 C as possible.

That saving would equate to about 60 Pence. It would be greater here as our power rates are higher at around 15 Pence a unit. They have just dropped our electricity bill from £85.00 to £65.00 a month as the price of oil falls and even fuel has come down a little, I'm buying diesel for £1.30 a litre now on special at the supermarkets, not too long ago it was £1.45 a litre.

Notty, UK

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