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Old 02-28-20, 03:07 PM   #9
MN Renovator
Less usage=Cheaper bills
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Join Date: Nov 2010
Location: Minneapolis, MN
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I originally wanted to do this to balance the HVAC airflow in my house, to monitor the temp rise of the furnace to replace the filter when airflow begins to drop, and to compare energy usage to the outdoor temperature. I've abandoned the project because the airflow balance isn't that critical or even that adjustable unfortunately. I can always pull nearby airport data to compare energy usage.

I already have a temperature sensor in the nearest vent to the furnace and it gives a rough idea of the temp rise after 20 minutes of furnace run time compared to the temperature on the thermostat. I replace the filter as soon as the temp rise is 5 degrees higher than it originally reads with a fresh one. It's interesting to see how the temp rise is almost always 75 degrees for three months or so and over the course of the final month it will creep up a couple of degrees and in the course of a week it will go from 80 degrees temp rise to 85 degrees suddenly. They free flow well and once they start to clog the remaining 'tiny holes' flow the rest of the air that the clogged holes can't and the filter flow rapidly diminishes.
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