Replacing a Rheem/Ruud Rooftop Unit: Curb Compatibility Guide

By Taylor Metals — SMARTCurb Engineering  ·  Updated August 24, 2026  ·  4 min read

34 verified Rheem/Ruud RTU curb footprints — the current Renaissance, Resolute, and Endeavor lines, and the older lettered-prefix packaged units most contractors still find in the field.

What SMARTCurb has on file for Rheem/Ruud

SMARTCurb has verified curb geometry for 34 Rheem/Ruud rooftop-unit models. Every record in the atlas carries both brand names together — Rheem and Ruud are documented as sharing identical curb platforms model for model, so a curb built for a Rheem-badged unit fits the equivalent Ruud-badged nameplate and vice versa. Browse the full list on the Rheem/Ruud hub.

Rheem/Ruud's current commercial lines

Eight of the 34 verified models are current-generation, cabinet-typed commercial equipment, organized into three named lines. Renaissance Line covers small-to-medium commercial cabinets: Cabinet Type C carries the Commercial Prestige (RGECZT/RHPCZT, 6 ton) and Commercial Classic (RGECZR/RHPCZR, 3–5 ton) series on a shared chassis — a real example is on the Rheem/Ruud RGECZR036 page — while Cabinet Type D carries the larger Commercial Prestige Series (RACDZT/RGEDZT/RHPDZT), shown on the RACDZT090 page. Resolute Line is the large-tonnage platform, 15–30 ton, documented with one curb spanning both the 15–25 ton and 30 ton tiers. Endeavor Line covers smaller residential/light-commercial cabinets — Cabinet A (RGEAYB/RACAYB/RHP(A/X)YB, 2–5 ton) and the newer Achiever Plus series (RGEAYC 'A' cabinet + RGEXYC 'X' cabinet) — with the RGEAYB024AJT model on file using R-454B refrigerant, among the newest equipment in this atlas. See a real Endeavor example on the RGEAYB024AJT page.

The legacy lettered-prefix reality

The remaining 26 verified models are older packaged equipment, documented from secondary sources rather than current Rheem/Ruud literature — exactly what you'd expect from equipment old enough that it no longer carries a marketed line name. These carry a range of prefix codes: RRC, RRE, RRG, RSC, RSN, RPND, RJKAA, RQNLB, and GPF/GPG among them, generally followed by a size code that steps up with tonnage within each prefix family. A real example is on the Rheem/Ruud GPF21T300 page. If a Rheem or Ruud nameplate on the roof doesn't match Renaissance, Resolute, or Endeavor, this older lettered-prefix category is almost certainly where it belongs — SMARTCurb still has the curb geometry on file.

These older records make up the majority of what's in the atlas for this brand — 26 of 34 verified models, roughly three out of every four. That's a useful expectation to carry onto the roof: for Rheem and Ruud specifically, the equipment you're most likely to actually find on an existing building skews toward this legacy lettered-prefix category rather than the three current-generation lines, simply because there's been more time for it to accumulate in the field. None of that changes how you approach the replacement — the curb geometry is verified either way — but it does mean checking the model page against the specific prefix and size code is usually the more direct path than trying to match against Renaissance, Resolute, or Endeavor first.

Matching the prefix, not just "Rheem" or "Ruud"

Because both brand names cover the same underlying equipment, the prefix code on the nameplate is what actually narrows a unit down to one verified curb — not which of the two brand names happens to be printed on it. Two units with the same prefix and size code, one badged Rheem and one badged Ruud, are the same physical curb in this atlas. That single-nameplate structure is also part of why this guide treats them as one manufacturer throughout rather than writing two nearly-identical guides — the underlying curb data doesn't distinguish between the two brands at all, only the badge printed on the cabinet does.

Every Rheem/Ruud page carries its original pattern drawing

Every Rheem/Ruud model page in the atlas includes the original curb pattern drawing alongside the verified footprint, viewable directly on the page — particularly useful on the legacy lettered-prefix units, where documentation quality varies more than it does across the three current lines.

Before you order

Confirm the exact model prefix and size code on the nameplate, then pull the real curb dimensions using the outside-corner datum convention, and cross-check both against the matching model page's footprint and pattern drawing before assuming a same-family swap is a clean fit. This sequence matters more than usual here: with a legacy lettered-prefix unit specifically, don't assume the brand name on the cabinet narrows things down at all — it's the prefix and size code doing that work, and only the model page and a real tape measure can confirm the fit.

When the replacement isn't Rheem/Ruud-to-Rheem/Ruud

The adapter SMARTCurb compiles isn't restricted to same-brand pairings. Each model page lists nearest-footprint compatible pairings across manufacturers as a starting point, ranked by how closely each candidate's overall curb footprint matches the one you started from. Open the SMARTCurb workspace, pick your existing Rheem or Ruud unit and its replacement, and see the real compiled result.