The greater the differential in temperature between the inside and the
outside, the faster the garage will lose heat. Therefore, on a 25 degree
day outside, your furnace will run more when the thermostat is set at 65
degrees than it will if the thermostat is set at 45 degrees, because you
will lose more heast and the furnace must replace the heat you lose. That's
why you set your thermostat back to a lower temperature - it's cheaper to
maintain a lower temperature..
Since heat is escaping at a greater rate when it's warmer inside, it will
indeed take a little more energy to raise the temperature from 60 to 65
degrees than it will to raise it from 45 to 50 degrees. But the point is
the cost of maintaining the temperature, not just the cost of the first rise
in temperature.
Karl
>
> This is a question for the engineers on the list. I am not an
> engineer. I live in NW Ohio (cold). I have a separate garage/shop
> heated with a natural gas furnace. I normally set the temperature
> around 50 when I leave and 65 when I am working. It is currently about
> 25 outside. My question. Assume my thermostat starts my furnace when
> the temperature drops 5 degrees from the current setting. Does it take
> more energy to raise the temp from 60 to 65 than from 45 to 50? If no
> then why am I turning it down and if yes, why?
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