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 Power-fin PBN0502-M9 and PBN0752-M9 are the two smallest M9 sizes: the 0502 fires 100-500 MBH with 425 MBH gross output, and the 0752 fires 150-750 MBH with 638 MBH gross output. Both are 85% thermal efficiency with 2-1/2" water connections; the 0752 adds 213 MBH of gross output and a larger 1-1/4" gas connection.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Lochinvar Power-fin PBN0502-M9 | Lochinvar Power-fin PBN0752-M9 |
|---|---|---|
| Heating input, minimum | 100 MBH | 150 MBH |
| Heating input, maximum | 500 MBH | 750 MBH |
| Gross output | 425 MBH | 638 MBH |
| Net AHRI water rating | 370 MBH | 554 MBH |
| Efficiency (thermal) | 85 % | 85 % |
| Water content | 3.6 gal | 4 gal |
| Water connections | 2-1/2" | 2-1/2" |
| Gas connection | 1" | 1-1/4" |
| Air inlet size | 5" | 5" |
| Vent size | 4" | 5" |
| Turndown | 5:1 | 5:1 |
The PBN0502-M9's printed ratings table lists 100 MBH minimum and 500 MBH maximum input, 425 MBH gross output and a 370 MBH net AHRI water rating; the PBN0752-M9 lists 150-750 MBH input, 638 MBH gross output and a 554 MBH net AHRI rating.
Both models print 85% thermal efficiency on their product pages, 5:1 turndown, 2-1/2" water connections and Category II/IV special gas venting; the gas connection steps from 1" on the 0502 to 1-1/4" on the 0752, and the air/vent sizes are 5"/4" versus 5"/5".
A sizing decision between the two rests on the load: the 0752 carries roughly 50% more gross output, so it suits larger commercial loads while the 0502 fits mid-sized buildings.
Lochinvar
The Lochinvar Power-fin PBN0502-M9 is a non-condensing copper-tube vertical commercial boiler rated 100-500 MBH input, 425 MBH gross output and a 370 MBH net AHRI water rating at 85% thermal efficiency.
Lochinvar
The Lochinvar Power-fin PBN0752-M9 is a non-condensing copper-tube vertical commercial boiler rated 150-750 MBH input, 638 MBH gross output and a 554 MBH net AHRI water rating at 85% thermal efficiency.
The PBN0752-M9 is larger: 750 MBH maximum input and 638 MBH gross output versus 500 MBH and 425 MBH on the PBN0502-M9.
Both require special gas venting (Category II or IV, AL29-4C stainless steel); the air connection is 5" on both, while the vent steps from 4" on the 0502 to 5" on the 0752.
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.