Multiple HVAC supply houses, including Warners’ Stellian, Binghamton Hardware, and HVAC Trust, all list identical dimensions for the Rinnai RU199iN, a level of consistency across independent retailers that confirms these numbers as accurate manufacturer specifications, useful now that the unit itself is no longer sold new and Rinnai’s own product page is your best remaining primary source.
The Rinnai RU199iN was a 199,000 BTU condensing natural gas tankless water heater measuring 31.3 inches tall by 18.5 inches wide by 11.45 inches deep, weighing 64 pounds, with a 0.96 Energy Factor and Energy Star certification. It delivered a flow rate ranging from 0.26 GPM at minimum activation up to approximately 11 GPM at maximum, depending on the specific temperature rise required.
Full Spec Sheet
Based on consistent data across Rinnai’s own product listing and multiple independent HVAC retailers:
| Spec | Detail |
|---|---|
| Heating capacity | 199,000 BTU |
| Flow rate | 0.26 to 11 GPM (varies by source, likely reflecting different temperature rise assumptions) |
| Dimensions | 31.3”H x 18.5”W x 11.45”D |
| Weight | 64 lbs |
| Energy Factor | 0.96 |
| Thermal efficiency | 96% (condensing technology) |
| Energy Star compliant | Yes |
| Ignition | Direct electronic |
| Installation | Indoor, residential and commercial |
| Fuel type | Natural gas (RU199iN) |
What “Condensing” Means for This Unit
The RU199iN’s condensing design is the core reason it achieved its high 96% thermal efficiency rating. Condensing tankless units extract additional heat from the exhaust gases before venting them, rather than allowing that heat to escape as waste, which non-condensing units do. This is why the RU199iN’s Energy Factor (0.96) sits meaningfully higher than typical non-condensing units in the same BTU class, which commonly rate in the 0.80s.
Flow Rate: Understanding the Range
You’ll find slightly different maximum GPM figures across different retailers and sources, some listing up to 9.8 GPM, others up to 11 GPM. This isn’t a contradiction, it reflects the same physics that affects every tankless water heater: maximum flow rate depends on the required temperature rise, which in turn depends on your incoming groundwater temperature. Warmer climate installations can achieve the higher end of this range, while colder climates or larger required temperature rises will see lower usable flow, a detail worth understanding regardless of which specific tankless unit you’re evaluating.
Physical Installation Footprint
At 31.3 inches tall and weighing 64 pounds, the RU199iN required a genuine wall-mounted installation with adequate support, considerably heavier than the compact electric tankless units in a different product category. This weight and size reflect the more substantial internal components (heat exchanger, condensing mechanism, gas valve assembly) needed to achieve its high BTU output and condensing efficiency.
Energy Star Certification
Unlike many electric tankless water heaters, which generally don’t carry Energy Star certification, the RU199iN’s Energy Star compliance reflects real third-party verified efficiency standards for gas tankless water heaters specifically. This certification was a meaningful selling point during the unit’s active production, and it’s a useful data point if you’re comparing the RU199iN’s historical specs against currently available condensing gas units.
What This Means If You Already Own One
If you own an RU199iN, these specifications remain directly relevant for maintenance and troubleshooting purposes, confirming your unit’s rated capacity and physical requirements even though it’s no longer sold new. Referencing your specific unit’s technical data sheet (located inside the front cover of the water heater, according to Rinnai’s own installation manual) is the most authoritative source for any spec verification specific to your individual unit.
For a full comparison of how these specs stack up against Rinnai’s current-generation replacement, see our RU199iN vs RXP199iN comparison.
Rinnai RXP199iN Condensing Tankless Water Heater - View Current Specs on Amazon
The Bottom Line
The Rinnai RU199iN’s specs, 199,000 BTU, up to 11 GPM, 96% thermal efficiency, and Energy Star certification, reflect a genuinely high-performing condensing tankless unit for its category. These figures remain useful reference points for existing owners and for comparing against Rinnai’s current lineup if you’re shopping new.
Frequently Asked Questions
What is the BTU rating of the Rinnai RU199iN? 199,000 BTU, placing it among the higher-capacity residential condensing tankless units Rinnai offered.
What is the maximum flow rate of the Rinnai RU199iN? Sources vary between 9.8 and 11 GPM maximum, reflecting different assumed temperature rise conditions, actual usable flow depends on your specific groundwater temperature.
How much does the Rinnai RU199iN weigh? 64 pounds, according to consistent data across Rinnai’s own listing and multiple independent HVAC retailers.
What are the dimensions of the Rinnai RU199iN? 31.3 inches tall by 18.5 inches wide by 11.45 inches deep.
Is the Rinnai RU199iN Energy Star certified? Yes, it carries Energy Star certification, reflecting verified efficiency standards for condensing gas tankless water heaters.
What is the Energy Factor of the Rinnai RU199iN? 0.96, a figure reflecting its condensing technology’s high thermal efficiency compared to standard non-condensing units, which typically rate in the 0.80s.
Does the Rinnai RU199iN run on natural gas or propane? The RU199iN specifically runs on natural gas. Rinnai offered separate propane-compatible models under different model designations in the same series.
What does “condensing” mean for a tankless water heater? Condensing units extract additional heat from exhaust gases before venting, rather than letting that heat escape as waste, resulting in higher overall efficiency compared to non-condensing designs.
Can I still find the official spec sheet for my RU199iN? Rinnai’s own product page and multiple independent HVAC retailers maintain spec listings for the discontinued model, and your unit’s specific technical data sheet is located inside the front cover of the water heater itself.
How does the RU199iN’s efficiency compare to its current replacement? Rinnai’s current Smart Sense condensing models, including the RX199iN and RXP199iN, maintain similarly high efficiency ratings in the same BTU class, reflecting the continuation of the same core condensing technology.
References
- Rinnai official product specifications for the RU199iN, accessed July 2026: https://www.rinnai.us/residential/product-detail/ru199in
- Warners’ Stellian, Binghamton Hardware & HVAC Supply, and HVAC Trust product listings confirming consistent RU199iN specifications, accessed July 2026