I did a Duct Blaster® test with the wrong ring setting on my DG-700. Is there a way to calculate the correct reading?

Yes, there is. 

Channel B of the DG-700 is actually measuring a pressure at the flow sensor of the fan and converting the pressure to flow based on the Devise and Configuration settings on the gauge. Appendix B of the Duct Blaster manual has Flow Conversion Charts that allow you to determine what fan pressure the gauge was reading during the test. Here is an example that will demonstrate the process. Let’s say you recorded a reading of 260 CFM and had the DG-700 configuration set to Ring 1. On your way home you are thinking that the home should have been much tighter and you realize that you actually had Ring 2 installed on the Duct Blaster fan.

Here is the process to find the correct reading: 

  • Follow down the Ring 1 column until you reach 260 CFM
  • Follow across to the Fan Pressure column and you will see that you were measuring a fan pressure of 40 Pascals during the test
  • Follow across to the Ring 2 column and see that 99 CFM is the correct reading


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