Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
Boilers.ca is a brand of ROMA Heating & Cooling · Licensed gas contractor LGA0202903
Comparison
Verdict in brief
The atmospheric CBN500 and fan-assisted CBN0497 are the adjacent sizes where Lochinvar's Copper-Fin lines hand off: both land near 500 MBH of input (500 vs 495), but the CBN500 is 82.0% thermal efficiency with a built-in draft diverter and two-stage firing, while the CBN0497 is 84% with fan-assisted sealed combustion and a 6" vent instead of 10".
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Lochinvar Copper-Fin Atmospheric CBN500 | Lochinvar Copper-Fin Fan Assisted CBN0497 |
|---|---|---|
| Heating input, minimum | 250 MBH | 250 MBH |
| Heating input, maximum | 500 MBH | 495 MBH |
| Gross output | 410 MBH | 416 MBH |
| Net AHRI water rating | 357 MBH | 362 MBH |
| Efficiency (thermal) | 82 % | 84 % |
| Water content | 1.4 gal | 1.9 gal |
| Space-heating water connections | 2" | 2" |
| Gas connection | 1" | 1-1/4" |
| air-inlet-size | — | — |
| Vent size | 10" | 6" |
| Firing | Two-stage (high/low fire) | Two-stage (high/low fire) |
| Shipping weight | 345 lb | 440 lb |
The two boilers cover almost the same load: 250 to 500 MBH input on the CBN500 against 250 to 495 MBH on the CBN0497, with gross outputs of 410 and 416 MBH and AHRI net ratings of 357 and 362 MBH. A heat-loss calculation decides between them, not the ceiling.
The engineering difference is combustion and venting. The CBN500 is a conventional negative-draft Category I boiler with a built-in draft diverter and a 10" Type B vent; the CBN0497 is a fan-assisted Category I unit with a sealed combustion chamber and a 6" vent, so it can use outdoor installation venting and fits through a standard 36" doorway.
Efficiency and connections also split: 82.0% thermal on the CBN500 versus 84% on the CBN0497, with both on 2" NPT water connections and a 1" versus 1-1/4" gas connection. Firing stays two-stage high/low on both, and the submittals print 10-year heat-exchanger warranties.
The Copper-Fin Atmospheric CBN500 tops the atmospheric line at 250 to 500 MBH input with 410 MBH gross output and a 357 MBH AHRI net rating at 82.0% thermal efficiency.
The Copper-Fin Fan Assisted CBN0497 opens the eight-size line at 250 to 495 MBH input with 416 MBH gross output and a 362 MBH AHRI net rating at 84% thermal efficiency, on a 6" vent.
The fan-assisted CBN0497 at 84% thermal efficiency, against 82.0% for the atmospheric CBN500.
It is fan-assisted with a sealed combustion chamber, so it vents through 6" pipe, while the atmospheric CBN500 is a natural-draft Category I appliance that needs a 10" Type B vent.
Yes. Both use two-stage high/low firing; the atmospheric line uses a two-stage solid state temperature control and the fan-assisted line a two-stage electronic temperature control.
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.