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## Friday, October 10th, 2008

### Morning Temperature at 8 AM

Categories: [ Science ]

I've been thinking how to automatise the process of setting the car engine's heating time in the morning depending on the outside temperature. Since heating is not overly expensive, I've decided that a cheap timer switch should do the trick. As to how long the engine should be heated… Well, statistics may help here. The graphs on the left represents the average temperature in the morning at 6 and at 8 over the past 6 years (2002 – 2008). From the graph, it's easy to see that there are clear periods where the temperature is between this and that limit.

In a nutshell and in month-day format:

• 01-01 – 03-01: 2 hours
• 03-01 – 03-25: 1 hour
• 03-25 – 05-01: 30 minutes
• 05-01 – 10-01: no heating
• 10-01 – 12-15: 30 minutes
• 12-15 – 12-31: 1 hour

This represents 214 hours of heating in the year, amounting to 6.90 EUR (with a 400 W heater, and a rate of 0.08 EUR/kWh). With the additional inside heater (add 950 W), it costs 23.30 EUR. This is almost 40% more expensive than the optimised calculation in the previous article, but a device combining termperature sensor with a clock is hard to find and will cost 50 to 100 EUR, when a mechanical clock switch can be found for 5 EUR.

[ Posted on October 10th, 2008 at 23:55 | 1 comment | ]

##### Warm up times for Defa's timer

Comment #1, Henrik (Jyväskylä, Finland), October 13th, 2008 at 12:20

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