Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
Both the Smith GBX-175 and the Smith GBX-195 belong to the Smith Cast Iron Boilers GBX Series (discontinued) line of non-condensing boilers. The Smith GBX-175 is documented at 175 MBH input, 143 MBH gross output and 82% AFUE, while the Smith GBX-195 is documented at 195 MBH input, 139 MBH gross output and 82% AFUE. Smith GBX-195 lists 20 MBH more input than Smith GBX-175 (195 MBH against 175 MBH). Both list the same published AFUE of 82%.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Smith GBX-175 | Smith GBX-195 |
|---|---|---|
| AGA input (as printed) | 175 MBH | 195 MBH |
| DOE heating capacity | 143 MBH | 139 MBH |
| Net I=B=R water rating | 124 MBH | 139 MBH |
| AFUE | 82 % | 82 % |
| Water content | 8.56 gal | 9.84 gal |
| Supply / return tappings | 1-1/2" NPT supply / 1-1/4" NPT return | 1-1/2" NPT supply / 1-1/4" NPT return |
| Fuel | Natural gas or propane | Natural gas or propane |
Published ratings: the Smith GBX-175 is rated 175 MBH input, 143 MBH gross output and 82% AFUE; the Smith GBX-195 is rated 195 MBH input, 139 MBH gross output and 82% AFUE. Smith GBX-195 lists 20 MBH more input than Smith GBX-175 (195 MBH against 175 MBH). Both list the same published AFUE of 82%.
The boiler water content differs: the Smith GBX-175 lists 8.56 gal, while the Smith GBX-195 lists 9.84 gal.
Both records print the same AFUE (82%), water connections (1-1/2" NPT supply / 1-1/4" NPT return) and fuel (Natural gas or propane), per the cited sources.
Smith Cast Iron Boilers
The Smith GBX-175 is a discontinued residential cast-iron water boiler rated 175 MBH AGA input with 143 MBH DOE heating capacity, 124 MBH net I=B=R and 82% AFUE, on 1-1/2" supply and 1-1/4" return tappings.
Smith Cast Iron Boilers
The Smith GBX-195 is a discontinued residential cast-iron water boiler rated 195 MBH AGA input with 139 MBH DOE heating capacity, 139 MBH net I=B=R and 82% AFUE, on 1-1/2" supply and 1-1/4" return tappings.
The Smith GBX-195 lists 195 MBH, against 175 MBH on the Smith GBX-175, per the cited documentation.
Both list the same AFUE of 82%.
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.