Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The Q175SN and Q205SN are the two largest heating-only Q-Series boilers and share the same 141 lb, 26 in wide, 31.4 in tall cabinet. The Q205SN prints a 205,000 BTU central-heating capacity and a 41,000 BTU minimum bullet against the Q175SN's 175,000 BTU capacity and 35,000 BTU minimum.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Rinnai Q175SN | Rinnai Q205SN |
|---|---|---|
| Minimum input (hero bullet) | 35 MBH | 41 MBH |
| Central heating capacity | 175 MBH | 205 MBH |
| Product weight | 141 lb | 141 lb |
| Product width | 26 in | 26 in |
The Q175SN and Q205SN top the Q-Series in the heating-only sizes. Their pages print minimum-input bullets of 35,000 and 41,000 BTU and central-heating capacities of 175,000 and 205,000 BTU — a 30,000 BTU step at the ceiling and a 6,000 BTU step at the floor.
The physical cabinet is identical: 141 lb, 26 in wide by 31.4 in high by 15.2 in deep, with a 3/4" MNPT gas connection. Both are heating-only, so neither has DHW connections or a flow row, and both carry the Q-Series page-print bug of a truncated "N (maximum)" maximum-input bullet.
Because the minimum fires differ by only 6,000 BTU, the practical difference between the two in mild weather is small; the 205SN's extra ceiling is what a larger heat-loss calculation buys. Both pages print Residential ENERGY STAR and SCAQMD Ultra Low NOx rows and no AFUE or venting figures.
Rinnai
The Rinnai Q175SN is a heating-only model in the Q-Series: a condensing boiler with a 175,000 BTU central-heating capacity and no domestic hot water production, at 141 lb.
Rinnai
The Rinnai Q205SN is a heating-only model in the Q-Series: a condensing boiler with a 205,000 BTU central-heating capacity and no domestic hot water production, at 141 lb.
The central-heating capacity (175,000 against 205,000 BTU) and minimum input (35,000 against 41,000 BTU). Cabinet, weight, connections and the printed ENERGY STAR and SCAQMD rows are identical.
The Q-Series pages are live on rinnai.ca but unlinked from the current condensing-boilers navigation, which lists only the I-SERIES+ line. Boilers.ca records the line as a legacy generation; confirm current availability with Rinnai.
The Q205SN, when the room-by-room heat-loss calculation approaches or exceeds the Q175SN's 175,000 BTU capacity. The two share the same cabinet, so there is no footprint penalty.
A consultation includes a heat-loss review so the size is right the first time.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Sources and verification
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.