Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The 19HE-9 and 19HE-12 bracket the top of the 19HE line: 1,262 versus 1,750 MBH gross output, 1,559 versus 2,165 MBH gas burner capacity, and 3" supply with a 4" return on the -12 against 3"/3" on the -9. The -12 also needs a 12" vent with the supplied transition collar. Both are 80 psi water / 15 psi steam boilers with the same oil, gas or combination firing choice.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Smith 19HE-9 | Smith 19HE-12 |
|---|---|---|
| Gas burner capacity (as printed) | 1,559 MBH | 2,165 MBH |
| Gross output (as printed) | 1,262 MBH | 1,750 MBH |
| Net I=B=R water rating | 1,097 MBH | 1,522 MBH |
| Thermal efficiency — oil | 83.5 % | 83.4 % |
| Thermal efficiency — gas | 81 % | 80.8 % |
| Flue pipe diameter | 10" | 10" (+12" vent) |
| Recommended supply / return piping | 3" supply / 3" return | 4" supply / 3" return |
Both boilers are part of the ten-size 19HE line that Smith's product page describes as ranging from 308 to 1,750 MBH. The -9 is a nine-section, 37.7 HP boiler at 1,262 MBH gross; the -12 is a twelve-section, 52.3 HP boiler at 1,750 MBH gross — the top of the line. Net I=B=R water ratings are 1,097 and 1,522 MBH respectively.
The installation envelope changes at the top. 19IOM-8R Table 6 moves the -12 to a 3" supply with a 4" return at 171 GPM (the -9 stays 3"/3" at 123 GPM), and the manual's tapping diagram and notes show 11- and 12-section boilers require a 12" vent connection with a transition collar provided by Smith. A 10" flue is printed for both in BSG-10, so the 12" requirement comes from the vent system sizing, not the boiler outlet alone.
Efficiency stays flat at the top: 83.5% oil / 81.0% gas for the -9 and 83.4% / 80.8% for the -12 in BSG-10. The G19HE-5 brochure repeats the oil figure in the gas column for these sizes; the model records use BSG-10's separate gas figure and carry an editorNote about the discrepancy. Choose between them on the calculated load, not on an efficiency difference.
Smith Cast Iron Boilers
The Smith 19HE-9 is a 37.7 HP cast-iron sectional power-burner boiler rated 1262 MBH gross output — 1559 MBH gas or 10.8 GPH No. 2 oil burner capacity — with a 10" flue connection and printed thermal efficiencies of 83.5% (oil) and 81% (gas).
Smith Cast Iron Boilers
The Smith 19HE-12 is a 52.3 HP cast-iron sectional power-burner boiler rated 1750 MBH gross output — 2165 MBH gas or 15 GPH No. 2 oil burner capacity — with a 10" (+12" vent) flue connection and printed thermal efficiencies of 83.4% (oil) and 80.8% (gas).
The 19HE-12 at 1,750 MBH gross output and 52.3 boiler horsepower, per BSG-10 and G19HE-5 — the top of the ten-size line.
Yes. 19IOM-8R states 11- and 12-section boilers require a 12" diameter vent connection with a transition collar provided by Smith.
19IOM-8R Table 6 recommends 3" supply and return piping for the 19HE-9 and a 4" return for the 19HE-12, both at 20 °F system drop.
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.