Here we are on the 3rd part of our quick AHRI guide! Before reading the following text, we always suggest you to carefully consult the General AHRI OM which you can find in the AHRI website. This is just a quick guide to provide you a general idea on how the process works. The first article is here!
In the previous and second article, we indicated that upon passing the test, the certified performances retain the right to be included in the AHRI Directory and no further action is required from the Applicant/Participant.
What happens if the test fails?
The test is considered failed if, by verifying the certified (calculated) data published in the Directory and comparing them with the laboratory data, they exceed the tolerances provided for in the certification standard referred to in the Product Operating Manual.
In the event of a failed test, the participant has the 3 following options:
- Repeating the test on a second (completely identical) sample of heat exchanger (for a maximum of 2 tests in total);
- Declaring “obsolete” the model (Discontinuing production) and all the models of the same BMG (again Basic Model Group = our geometry);
- Carry out the RERATING (downgrading) of the model and of the relative BMG as described below.
RERATING IS NOT A RE-CALIBRATION, IT’S A DOWNGRADE.
The applicant’s software provides the wrong value, and a rerating must be applied. In this case, the laboratory value calculated by AHRI will be the only one taken as correct. In addition, the notice that a rerating must to be performed on the BMG is written on the AHRI website for a 1 year period.
AHRI will require the software to apply the rerating value to all calculations of that BMG.
The downgrade must be performed in proportion to the rating ratio of the failed test: the ratio between the measured and the certified (calculated) quantity is the downgrade factor to be introduced. The recalibrated software must therefore calculate exactly, for the model that failed the test, the same or lower values (in the case of CAPACITY) or greater (in the case of PRESSURE DROPS) than those measured in the laboratory. The downgrade must be applied equally to all models belonging to the BMG. In order to be able to verify it, AHRI requires:
– Printout of the selection of the model that failed the test;
– Printout of selection of two additional models, belonging to the same BMG, calculated at the standard reference conditions of the BMG, calculated with both software releases “pre-rerating” and “rerated”;
– Rerated software release, with updated name and release number.
The percentage deviation between the calculation of the downgraded release and the original one must comply with the downgrading rate defined in the testing phase: it is therefore a correction factor to be applied uniformly to the entire BMG (= geometry).