Central AC System GuideRheem and Ruud are sibling brands built by Rheem Manufacturing, and each tops its lineup with an inverter-driven variable-speed air conditioner. This comparison lays out what each manufacturer publishes for its flagship so the specs can be read side by side. It does not pick a winner.
How to read this comparison
Efficiency, staging, and refrigerant are the fields shoppers most often line up across brands. Rheem and Ruud share engineering, and in this case both flagship pages state efficiency on the same SEER2 scale, which makes the published figures directly readable next to each other.
Every number below is quoted from the manufacturer's own page. Where any difference appears, it is noted rather than converted.
Rheem's published specs
Rheem's flagship variable-speed unit is the RA19AY, part of the Endeavor Line Prestige Series. The manufacturer publishes its efficiency in SEER2 and EER2, describes an inverter-driven compressor with a defined operating band, and lists the refrigerant it uses.
Rheem states the RA19AY modulates across a wide capacity range with an overdrive capability in extreme conditions.
Ruud's published specs
Ruud's flagship variable-speed unit is the UA19AY, part of the Endeavor Line Ultra Series. The manufacturer publishes its efficiency in SEER2 and EER2, describes the same inverter-driven compressor band, and lists the refrigerant it uses.
Ruud states the UA19AY carries the same operating characteristics its Rheem sibling publishes.
Where they differ on paper
Because Rheem and Ruud build these flagships on a shared platform, the published specs line up almost exactly. Both pages state up to 20 SEER2 and up to 13 EER2, both describe an inverter-driven compressor operating from 40 to 100 percent with a 115 percent overdrive, and both list R-454B refrigerant.
The practical difference on paper is branding and series name rather than the headline numbers, with Rheem using the Prestige Series name and Ruud using the Ultra Series name for the same published figures.