A Reddit thread in r/askaplumber asked directly: “Replace Rinnai RU199in with RXP199in?” and drew more than 10 responses from plumbers and homeowners working through exactly this decision. If your RU199iN needs replacing, or you’re comparing specs before a new purchase, this is the single most relevant comparison you can make right now.
The Rinnai RXP199iN is the direct current-generation successor to the discontinued RU199iN, sharing the same 199,000 BTU rating and nearly identical flow rate (up to 11.1 GPM versus the RU199iN’s up to 11 GPM), while adding a built-in recirculation pump the original RU199iN lacked. For anyone whose RU199iN needs replacement, or who’s shopping new and wants the closest match to what made the RU199iN a well-regarded unit, the RXP199iN is the clearest direct upgrade path.
Side-by-Side Comparison
| Spec | RU199iN (discontinued) | RXP199iN (current) |
|---|---|---|
| BTU rating | 199,000 | 199,000 |
| Max flow rate | Up to 11 GPM | Up to 11.1 GPM |
| Recirculation pump | Not built in | Built in |
| Installation | Indoor | Indoor/Outdoor |
| Platform | Original Sensei condensing | Smart Sense condensing |
| Price (2026 reference) | Historical ~$1,750-$2,199 | ~$1,735.53 (Amazon) |
| Amazon rating | N/A (discontinued) | 4.6 stars (119 reviews) |
The Built-In Recirculation Pump Is the Real Upgrade
This is the single most significant functional difference between the two units. RU199iN owners who wanted faster hot water delivery to distant fixtures typically needed to add a separate recirculation pump system, an additional cost and installation complexity that the RXP199iN eliminates by building the pump directly into the unit.
A recirculation pump keeps hot water actively circulating through your plumbing system (on a schedule or on-demand, depending on configuration), dramatically reducing the wait time for hot water to reach fixtures far from the water heater. This was a documented gap in the RU199iN’s design that Rinnai directly addressed with the RXP199iN.
Nearly Identical Core Capacity
Beyond the recirculation pump difference, the RXP199iN maintains essentially the same core performance envelope as the RU199iN, same 199,000 BTU rating, nearly identical maximum flow rate (11.1 GPM versus 11 GPM). This means if you were happy with your RU199iN’s capacity and hot water delivery, the RXP199iN should perform comparably from a raw heating and flow perspective, while adding the recirculation convenience.
Indoor/Outdoor Flexibility
The RXP199iN’s listing specifically notes indoor/outdoor installation flexibility, whereas the RU199iN was generally an indoor-only installation. This gives more placement flexibility for new installations, though if you’re simply replacing an existing RU199iN in its current location, this distinction may not significantly affect your decision.
Should You Upgrade or Look for a Direct RU199iN Replacement?
Based on the real plumber and homeowner discussion in the referenced Reddit thread, the general consensus favors upgrading to the RXP199iN rather than hunting for a remaining RU199iN unit, given the RXP199iN’s near-identical core specs plus the added recirculation pump value, at a comparable price point to what the RU199iN historically cost. The main scenario where sticking with an RU199iN-specific search makes sense is if you have a very specific reason to match existing equipment exactly, rather than simply replacing a failed unit.
Price Consideration
At approximately $1,735.53, the RXP199iN sits close to historical RU199iN street pricing (reported around $1,750 in a 2021 Reddit discussion), meaning you’re generally not paying a significant premium for the upgrade to built-in recirculation, a meaningful value proposition for anyone replacing an aging or failed RU199iN.
For the full picture of what a recirculation pump actually does and whether it’s worth prioritizing, see our recirculation pumps guide.
Rinnai RXP199iN Condensing Tankless Water Heater with Built-In Recirculation Pump - View on Amazon
The Bottom Line
The Rinnai RXP199iN is the clear direct successor to the discontinued RU199iN, matching its core BTU and flow rate performance while adding a built-in recirculation pump at a comparable price point. For most buyers replacing an RU199iN or shopping new in this capacity class, the RXP199iN is the straightforward upgrade choice.
Frequently Asked Questions
Is the RXP199iN a direct replacement for the RU199iN? Yes, it shares the same 199,000 BTU rating and nearly identical maximum flow rate, while adding a built-in recirculation pump the original RU199iN didn’t have.
What’s the main difference between the RU199iN and RXP199iN? The RXP199iN includes a built-in recirculation pump, which RU199iN owners typically had to add as a separate component if they wanted faster hot water delivery to distant fixtures.
Should I replace my RU199iN with an RXP199iN? Based on plumber and homeowner discussions, most reasonable comparisons favor the RXP199iN given its near-identical core specs plus the added recirculation pump value at a comparable price.
Is the RXP199iN more expensive than the RU199iN was? Pricing is comparable, the RXP199iN runs around $1,735.53 versus historical RU199iN pricing reported around $1,750, meaning the recirculation pump upgrade doesn’t come with a significant price premium.
Can the RXP199iN be installed outdoors? Yes, its listing specifically supports indoor/outdoor installation, offering more placement flexibility than the RU199iN, which was generally an indoor-only unit.
What does a built-in recirculation pump actually do? It keeps hot water actively circulating through your plumbing system, significantly reducing the wait time for hot water to reach fixtures located far from the water heater.
Is the RXP199iN’s flow rate really the same as the RU199iN’s? Very close, the RXP199iN is rated up to 11.1 GPM compared to the RU199iN’s up to 11 GPM, a negligible difference in practical terms.
Do I need a recirculation pump if my RU199iN never had one? Not necessarily, if you were satisfied with your hot water delivery time without one, you may not need this feature, though it’s a genuine convenience upgrade for many households.
Is the RXP199iN well reviewed? Yes, it holds a 4.6-star rating across 119 reviews on Amazon as of 2026, reflecting positive real-world reception.
What if I want to match my existing RU199iN exactly instead of upgrading? This generally requires searching secondary markets for remaining new-old-stock or used units, since the RU199iN is no longer sold new by Rinnai or major retailers.
References
- Reddit r/askaplumber community discussion specifically addressing RU199iN to RXP199iN replacement decisions, accessed July 2026
- Amazon.com live product listing and specifications for the Rinnai RXP199iN, accessed July 2026: https://www.amazon.com/s?k=Rinnai+RXP199iN
- Rinnai official product specifications for the discontinued RU199iN, accessed July 2026