Setting the Furnace Back

Even though it’s still August, it is starting to feel like fall. So people’s thoughts are turning to furnaces and heating the house.

I overheard someone denouncing the practice of setting the thermostat to a lower setting during the times when the house is unoccupied for a while. His argument was that sure, the furnace won’t run while the house cools down, but then it works extra to heat the house back up and all that savings is lost.

That is true if the time is short enough such that the house won’t stay at the lower temperature very long. The savings come with time at the lower temperature.

The reason for this is that the rate of heat transfer increases with a higher temperature difference. In other words, the warmer the inside of the house is, the more heat it will lose to the colder outside. Thus, the more heat the furnace will have to add to the inside.

So if you keep your house a little cooler, then not as much heat will escape, so you’ll see slight savings in furnace fuel costs. Think about what would happen if you set your thermostat to match the outside temperature: the furnace wouldn’t run at all. And your fuel costs would be zero. It’s just a linear ramp up from there: the higher the difference between your thermostat and the outside, the more the furnace will run. The times when the house is changing temperature is a wash – they cancel out.

Now the slaves and the officers were standing there, having made a charcoal fire, for it was cold and they were warming themselves; and Peter was also with them, standing and warming himself.

John 18:18

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This little article thingy was written by Some Guy sometime around 12:15 pm and has been carefully placed in the Technical category.

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