Canada-wide water heater information · On-site service in Metro Vancouver, BC
WaterHeating.ca is operated by CANRO Heating & Cooling
Comparison
Verdict in brief
Both are indoor condensing units in Rinnai's SENSEI RU family with the same UEF 0.95, the same 18.5 in x 11.4 in footprint, the same 3/4 in gas and water connections, the same 0.4 GPM minimum activation flow and the same 2 in PVC-family venting. The only real difference is the burner: the RU160iN is rated 15,000–160,000 BTU/h with 8.0 GPM (30 L/min) rated flow, and the RU180iN is 15,000–180,000 BTU/h with 9.0 GPM (34 L/min). Neither rated figure carries a stated temperature rise, so winter sizing uses Rinnai's flow curves, not the headline GPM.
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.
| Specification | Rinnai RU160iNGas tankless | Rinnai RU180iNGas tankless |
|---|---|---|
| Minimum gas input | 15,000 BTU/h | 15,000 BTU/h |
| Maximum gas input | 160,000 BTU/h | 180,000 BTU/h |
| Rated flow range | 0.26–8.0 GPM (1.0–30 L/min) at unspecified rise rise | 0.26–9.0 GPM (1.0–34 L/min) at unspecified rise rise |
| Maximum flow with parameter adjustment | 9 GPM (34 L/min) at unspecified rise rise | 10 GPM (38 L/min) at unspecified rise rise |
| Minimum activation flow | 0.4 GPM (1.5 L/min) | 0.4 GPM (1.5 L/min) |
| Uniform Energy Factor (UEF) | 0.95 | 0.95 |
| Max. equivalent vent length, 2 in twin pipe | 65 ft (20 m) | 65 ft (20 m) |
| Vent material | 2 in PVC/CPVC/polypropylene or 3 in/5 in concentric | 2 in PVC/CPVC/polypropylene or 3 in/5 in concentric |
| Gas connection | 3/4 in MNPT (19 mm) | 3/4 in MNPT (19 mm) |
| Water connections | 3/4 in MNPT cold in and hot out | 3/4 in MNPT cold in and hot out |
| Condensate drain | 1/2 in NPT (13 mm) | 1/2 in NPT (13 mm) |
| Electrical supply | 120 V, 60 Hz; 52 W normal, 1.3 W standby, 148 W with freeze protection; 4 A max, 10 A fuse | 120 V, 60 Hz; 65 W normal, 1.3 W standby, 148 W with freeze protection; 4 A max, 10 A fuse |
| Height | 26.4 in (670 mm) cabinet | 26.4 in (670 mm) cabinet |
| Width | 18.5 in (470 mm) | 18.5 in (470 mm) |
| Depth | 11.4 in (290 mm) | 11.4 in (290 mm) |
| Weight | 62 lb (28 kg) | 64 lb (29 kg) |
| Maximum altitude | 10,200 ft (3,109 m) | 10,200 ft (3,109 m) |
| Certification | ANSI Z21.10.3 / CSA 4.3 | ANSI Z21.10.3 / CSA 4.3 |
“—” 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.
The RU platform is where the two are identical. Both are rated UEF 0.95 on natural gas or propane, both take 2 in PVC, CPVC or polypropylene venting (or 3 in / 5 in concentric), both connect to 3/4 in gas and 3/4 in water, both drain condensate through a 1/2 in NPT connection, and both run on 120 V with Circ-Logic recirculation support through an external pump. Rinnai certifies both to ANSI Z21.10.3 / CSA 4.3.
The difference is the input cap and the flow that follows: 180,000 against 160,000 BTU/h, and 9.0 GPM (34 L/min) against 8.0 GPM (30 L/min) rated, rising to 10 GPM against 9 GPM with the parameter adjustment. Rinnai publishes these flows without a temperature rise and valid only for inlet water at 21 °C or below, so they are warm-inlet figures rather than winter performance. Metro Vancouver's rise to a 49 °C shower approaches 40 °C (72 °F), and the deliverable flow at that rise is read from the flow curves in manual 100000467.
Physically the two share the cabinet exactly (26.4 in high, 18.5 in wide, 11.4 in deep) and the same minimum activation flow of 0.4 GPM (1.5 L/min). The RU180iN is 2 lb heavier (64 lb / 29 kg against 62 lb / 28 kg) and draws 65 W in normal operation against the RU160iN's 52 W; both draw up to 148 W with freeze protection.
The practical question is demand, not preference. A household whose peak is one fixture at a time, or that wants to stay comfortably inside an existing gas supply, is usually served by the RU160iN; a home that occasionally runs two fixtures together, or has a higher winter rise, is assessed against the RU180iN's larger input. Both are sized from measured simultaneous flow, and the gas supply and vent route are confirmed before either is specified. Whether CANRO stocks a given model for a job is confirmed at consultation.
Rinnai · Gas tankless
The Rinnai RU160iN is an indoor condensing natural gas tankless water heater with a 15,000–160,000 BTU/h input, UEF 0.95 and up to 9 GPM (34 L/min) of flow at an unstated temperature rise. It is listed on rinnai.ca and is the mid-size RU model between the RU130i and RU180i.
Rinnai · Gas tankless
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.
Only if the peak demand needs the extra 20,000 BTU/h. Both share UEF 0.95, the same cabinet, venting, connections and minimum activation flow; the RU180iN adds capacity for a second simultaneous fixture, while the RU160iN suits one fixture at a time.
As published, yes: 9.0 GPM against 8.0 GPM rated. But neither figure states a temperature rise, so the honest comparison is flow at the same rise from Rinnai's flow curves.
They share the 2 in PVC-family venting pattern and the 3/4 in gas connection, but the gas line and meter are sized to the input: 160,000 BTU/h on the RU160iN against 180,000 BTU/h on the RU180iN. A supply check is part of the assessment.
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.
Sources and verification
Facts checked September 7, 2026. Last updated September 20, 2026. Technical reviewer: not yet assigned.