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Comparison

Rinnai RU199iN vs RU180iN

Verdict in brief

Both are indoor condensing RU-series units sharing UEF 0.95, the same cabinet and the same 2 in PVC-family venting, 3/4 in connections and 120 V supply. The real difference is input: the RU199iN is rated 15,000–199,000 BTU/h with a 9.8 GPM rated flow and an 11 GPM maximum, and the RU180iN is 15,000–180,000 BTU/h with 9.0 GPM rated and 10 GPM maximum. Neither maximum carries a stated temperature rise, so the winter flow-at-rise figure decides whether the smaller unit is enough.

Side by side

Published manufacturer figures with units. Storage and flow figures are different measures and are shown on their own rows; blanks mean not applicable or not published.

Comparison of Rinnai RU199iN and Rinnai RU180iN
SpecificationRinnai RU199iNGas tanklessRinnai RU180iNGas tankless
Minimum gas input15,000 BTU/h15,000 BTU/h
Maximum gas input199,000 BTU/h180,000 BTU/h
Rated flow range0.26–9.8 GPM (1.0–37 L/min) at unspecified rise rise0.26–9.0 GPM (1.0–34 L/min) at unspecified rise rise
Maximum flow with parameter adjustment11 GPM (42 L/min) at unspecified rise rise10 GPM (38 L/min) at unspecified rise rise
Minimum activation flow0.4 GPM (1.5 L/min)0.4 GPM (1.5 L/min)
Uniform Energy Factor (UEF)0.950.95
Electrical supply120 V, 60 Hz; 84 W normal, 1.3 W standby, 148 W with freeze protection; 4 A max, 10 A fuse120 V, 60 Hz; 65 W normal, 1.3 W standby, 148 W with freeze protection; 4 A max, 10 A fuse
Weight64 lb (29 kg)64 lb (29 kg)
Gas connection3/4 in MNPT (19 mm)3/4 in MNPT (19 mm)
Water connections3/4 in MNPT cold in and hot out3/4 in MNPT cold in and hot out
Condensate drain1/2 in NPT (13 mm)1/2 in NPT (13 mm)

“—” means not applicable to that system type or not published by the manufacturer. Flow figures are only comparable at the same temperature rise; UEF values are only comparable within the same draw pattern.

What actually separates them

The difference is the burner: 199,000 BTU/h against 180,000, with the RU180iN drawing 65 W normally and the RU199iN 84 W, and both 1.3 W standby and 148 W with freeze protection. Everything else on Rinnai's published data is shared: UEF 0.95, a 0.4 GPM minimum activation flow, 3/4 in gas and water connections, a 1/2 in condensate drain and a 64 lb (29 kg) cabinet.

Flow is published two ways and neither states a rise: a rated range of 0.26–9.8 GPM on the RU199iN against 0.26–9.0 GPM on the RU180iN, and a parameter-adjusted maximum of 11 GPM against 10 GPM. Rinnai's flow curves apply only to inlet water at 21 °C or below, so in a Metro Vancouver winter the rise to 49 °C is what the tables are read at, and two simultaneous showers are assessed against that figure rather than the maximum.

Rinnai Canada lists both models as ENERGY STAR and Wi-Fi capable. Both need 2 in PVC-family venting to an exterior termination, a condensate drain and a 120 V outlet, and both support recirculation through Circ-Logic with an external pump. The RU line is the outgoing platform behind the RX/RXP series, so availability is re-checked before ordering.

Rinnai · Gas tankless

Rinnai RU199iN

CurrentSold in Canada
Max input
199,000 BTU/h
Flow at unspecified rise rise
11 GPM (42 L/min)
Uniform Energy Factor (UEF)
0.95

The Rinnai RU199iN is an indoor condensing natural gas tankless water heater with a 15,000–199,000 BTU/h input, UEF 0.95, 2" PVC venting and up to 11 GPM (42 L/min) of flow at an unstated temperature rise. It is listed on rinnai.ca and is the largest residential RU model, with a propane version, the RU199iP.

Natural gasPropaneCondensing, PVC/CPVC/PP
Specifications, manuals and service

Rinnai · Gas tankless

Rinnai RU180iN

CurrentSold in Canada
Max input
180,000 BTU/h
Flow at unspecified rise rise
10 GPM (38 L/min)
Uniform Energy Factor (UEF)
0.95

The Rinnai RU180iN is an indoor condensing natural gas tankless water heater with a 15,000–180,000 BTU/h input, UEF 0.95 and up to 10 GPM (38 L/min) of flow at an unstated temperature rise. It is listed on rinnai.ca and sits one step below the flagship RU199iN.

Natural gasPropaneCondensing, PVC/CPVC/PP
Specifications, manuals and service

Frequently asked questions

Is the RU199iN worth it over the RU180iN?

Only if the peak demand needs the extra 19,000 BTU/h. Both share UEF 0.95 and the same cabinet; the RU180iN covers two sequential fixtures, while the larger unit adds capacity for a higher winter rise or a heavier simultaneous load.

Can I compare their GPM directly?

The rated ranges are comparable as published, but neither maximum states a temperature rise. Read both against the winter rise before deciding.

Do they use the same venting and power?

Yes. Both are condensing units taking 2 in PVC/CPVC/polypropylene or concentric venting to an exterior termination, with a condensate drain, and both run on 120 V.

Not sure which one fits your home?

A consultation includes a hot-water demand review so capacity is right for your winter, not the brochure's.

On-site service in Metro Vancouver, BC. Call to check availability.

Call 604-359-1081Request a consultation

Related

Sources and verification

Facts checked September 19, 2026. Last updated September 19, 2026. Technical reviewer: not yet assigned.

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