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I am trying to calculate the running cost of my clothes dryer and have bought myself an energy meter to check its usage.

I plugged the meter in, reset it, and then turned it over to the aggregate kWh mode and did a single drying session with wet clothes from the washing machine.

After the load had finished the meter read 1.828 kWh and the total time was 1h 13m.

So as I understand it, a single load used 1.828 kWh, and as we are doing about 7 loads per week that would be a total of 665 kWh / year. At the current rate of 33c per kWh the annual running cost is therefore about $219.

Now this to me is a bit strange as just about every website I have seen says that dryers should be costing upwards of $400 per annum for this kind of usage. In addition, my dryer is only a 2 out of 5 stars for energy efficiency.

Can anyone see a problem with my math or logic?

Grant
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  • are those websites using the same cost / unit for electricity? Are you using a low rate cost - nightime or somesuch? – Solar Mike Jun 18 '18 at 11:02
  • yes i believe so. and no, not using any low rate cost or anything like that. – Grant Jun 18 '18 at 11:56
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    Collect more than one data point! “Typical” Loads will vary. Your home’s voltage may vary(brown out). One point does not qualify as the population. You want certainty with your estimation. – GisMofx Jun 18 '18 at 13:51

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You measured one load to take 1.8 kWh. That implies that 7 loads would take 12.6 kWh. If these 7 loads are repeated 52 times per year, then a whole year of operating takes 655 kWh.

As a sanity check, 1.828 kWh over 1 hour and 13 minutes comes out to 1.5 kW, which is plausible for some type of clothes dryer.

\$0.33 per kWh sounds very high, but going with that, 655 kWh would cost $216.

It seems your calculations are correct.

Web sites that claim some appliance costs some amount per year to operate are a very rough guide at best, complete fabrication at worst. These sites usually have some agenda, so push the number towards whatever makes their argument look better. They also rarely state assumptions. Even then, usage patterns for something like a clothes dryer vary so widely, as do electricity prices, that they can pick from a wide range of values and then claim a case that justifies what they picked.

Keep monitoring the electricity usage of your dryer. It probably varies quite a bit from load to load. There will be inevitable variations in amount of clothes that are being dried, the ambient humidity, the wetness of the clothes, and other factors that are hard to predict. Over a whole year, you'll get a much better idea of the expected power usage of the dryer.

Are you really sure that you pay $0.33 incrementally per kWh? That's probably correct for some part of the world at least some of the time, but sounds rather high. If your area has time of day metering, it might be worth your trouble to arrange to run the dryer over night when the rates are lower.

If you want to save money, try using a plain old clothes line, at least during the warm parts of the year.

Olin Lathrop
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  • Thanks Olin yes in Australia at the moment we are all paying around 30c per kWh. Very high indeed. Thank you for your suggestions, I will continue to monitor and see if there is any variance. – Grant Jun 18 '18 at 11:40