“Design is not just what it looks like and feels like. Design is how it works.” –Steve Jobs


ASTM-E84, 25/50,
solarwall, inspirewall, pressure drop test,

The charts to the right and below show the pressure drop test results of both the metal SVPs and Sunreps Geotextile 307 collector. The size of the holes in the respective collector surfaces determine how fast air can pass through. The smaller the hole the lower the flow but the higher the temperature.



10 cfm per sq ft of air-flow through a collector is scientifically noted as the optimum. The best test results Sunreps has seen for a metal collector is 7.6 cfm per sq ft. Sunreps' 307 collector has a flow rate of 8.5. Overall this difference is rather small but in the field of bragging rights, Sunreps 307 is the current winner.

Below is the test result for the Sunreps 307 collector fabric. To be used in the commercial building sector all surfaces of a duct need to be fire resistant to a specified level. The test results shown below meet those requirements.

pressure drop, solar air flow, cfm, solar ventilation pre-heater, fabric solar collectors

There is basically one test required to understand the capabilities of a Solar Ventilation Pre-Heater and that is how fast air will pass through the collector surface at a specific static pressure level. The collector's color, profile and texture are also relevant. In the results below all tests were conducted on black collectors. 


.10 inch H2O of pressure is the baseline for solar ventilation pre-heaters. The .10 inch level of pressure or above guarantees that the wind will not pull the majority of solar heat off the collector surface.

Test Results for Sunreps 307 SVP collector