Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The fan-assisted CBN0747 and Copper-Fin II CHN0752 are the closest cross-line pair in the family: 350 to 745 MBH versus 250 to 750 MBH, both on 2" NPT water connections and an 8" vent, but the CBN0747 is 84% with two-stage firing and the CHN0752 is 85% with proportional firing up to 4:1 and the SMART SYSTEM control.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Lochinvar Copper-Fin Fan Assisted CBN0747 | Lochinvar Copper-Fin II CHN0752 |
|---|---|---|
| Heating input, minimum | 350 MBH | 250 MBH |
| Heating input, maximum | 745 MBH | 750 MBH |
| Gross output | 626 MBH | 638 MBH |
| Net AHRI water rating | 544 MBH | 555 MBH |
| Efficiency (thermal) | 84 % | 85 % |
| Water content | 2.4 gal | 2.4 gal |
| Space-heating water connections | 2" | 2" |
| Gas connection | 1-1/4" | 1-1/4" |
| Air inlet size | — | 8" |
| Vent size | 8" | 8" |
| Firing | Two-stage (high/low fire) | Proportional, up to 4:1 turndown |
| Shipping weight | 550 lb | 543 lb |
The two models nearly touch at the top: the CBN0747 covers 350 to 745 MBH input with 626 MBH gross output and a 544 MBH AHRI net rating at 84%; the CHN0752 covers 250 to 750 MBH input with 638 MBH gross output and a 555 MBH AHRI net rating at 85%. The Copper-Fin II also fires 100 MBH lower at minimum.
Connections and venting are nearly identical: both use 2" NPT water on 6-1/2" centers, a 1-1/4" gas connection and an 8" vent, and both are fan-assisted Category I designs. The CHN0752's submittal adds Category IV AL29-4C stainless and DirectAire/powered sidewall options.
The decision usually comes down to control and cabinet: the CHN0752 carries the SMART SYSTEM cascade control and proportional firing, and weighs 543 lb against the CBN0747's 550 lb; the CBN0747 keeps the simpler two-stage control with diagnostic lights. Both submittals print 10-year heat-exchanger warranties.
The Copper-Fin Fan Assisted CBN0747 reaches 350 to 745 MBH input with 626 MBH gross output and a 544 MBH AHRI net rating at 84% thermal efficiency, closing the 2" water-connection group.
Lochinvar
The Copper-Fin II CHN0752 reaches 250 to 750 MBH input with 638 MBH gross output and a 555 MBH AHRI net rating at 85% thermal efficiency, closing the 2" water-connection group.
Very close: 745 versus 750 MBH maximum input and 626 versus 638 MBH gross output, with the same 8" vent, 2" water connections and 1-1/4" gas connections.
The Copper-Fin II CHN0752, whose I&O minimum input is 250 MBH against the fan-assisted CBN0747's 350 MBH.
The CHN0752 with the SMART SYSTEM control, 8-boiler cascade and proportional firing up to 4:1; the CBN0747 uses 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.