Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
The AHRI rating conditions for DX cooling coils is indoor wet-bulb temperature = 19.44 C (67 F) and outdoor dry-bulb temperature = 35 C (95 F). If you use these temperatures in your performance curve equation you should see where the 0.786 is coming from. At this condition the program expects a value of 1.0 +- 10%. Performance curves will typically be normalized to 1 at this rating point.
The next warning Heating Seasonal Performance Factor calculated is not at the AHRI test condition is telling you that the performance curves entered do not offer the performance at the conditions used to evaluate HSPF. This is due to the performance curve's min/max X and Y not including the indoor wet-bulb and outdoor dry-bulb temperatures used during this rating procedure calculation. See the Engineering Reference section Single-Speed DX Heating Coil Standard Ratings for more information.
