A contractor explains to a customer why a new unit's SEER2 rating is numerically lower than a comparable older unit's SEER rating, even though cooling performance is similar. What is the primary reason for this difference?
- ASEER2 ratings are calculated using the Celsius temperature scale instead of Fahrenheit
- BSEER2 measures heating performance instead of cooling performance
- CSEER2 no longer accounts for part-load efficiency in its calculation
- DSEER2 testing uses a higher, more realistic external static pressure that better represents actual ductwork resistance
Show answer & explanationAnswer & explanation
Correct answer: D. SEER2 testing uses a higher, more realistic external static pressure that better represents actual ductwork resistance
The updated DOE M1 test procedure used for SEER2 applies a higher external static pressure (0.5 in. w.c. for most split systems, versus the older 0.1 in. w.c. used for SEER) to better represent real-world ductwork resistance. This more demanding test condition results in numerically lower SEER2 values for equipment of similar actual performance.
Why the other options are wrong
- A. Temperature scale is unrelated to the rating methodology change.
- B. SEER2 still measures cooling seasonal efficiency, just under revised test conditions.
- C. SEER2 still incorporates part-load performance in its weighted calculation.
SEER2 Test Procedure Change
SEER2 uses the updated DOE M1 test procedure with higher, more realistic external static pressure than the older SEER test, resulting in lower numerical ratings for similar equipment.
- SEER2 test uses about 0.5 in. w.c. static pressure vs. 0.1 in. w.c. for SEER
- Reflects real-world duct restriction more accurately
- SEER2 and SEER numbers are not directly comparable
Memory trick: SEER2 turns up the duct resistance dial, so the number takes a dial-down.