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Old 06-07-16, 08:29 PM   #5
Apprentice EcoRenovator
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I use 0.018 BTU/ft^3/deg F, the same as bmxeroh. It's almost certainly more accurate than typical temperature and airflow measurements. A one degree error on inlet and outlet temperatures could cause 10% error on temperature rise, plus another 10% air flow error, results in an easily believable 20% error. Accurate BTU measurements in HVAC systems can be a real challenge.

The largest assumption is that you are not adding or removing moisture. Then you would need a psychrometric chart.
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