Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The Dunkirk PSB-6D and Dunkirk PSB-7D are both non-condensing boilers in the Dunkirk Boilers PSB Plymouth Steam Boiler line. The Dunkirk PSB-6D is documented at 187 MBH input, 153 MBH heating capacity and 82% AFUE, while the Dunkirk PSB-7D is documented at 225 MBH input, 183 MBH heating capacity and 82% AFUE. Dunkirk PSB-7D lists 38 MBH more input than Dunkirk PSB-6D (225 MBH against 187 MBH). Both list the same published AFUE of 82%. Dunkirk PSB-7D lists 72 lb more shipping weight than Dunkirk PSB-6D (584 lb against 512 lb).
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Dunkirk PSB-6D | Dunkirk PSB-7D |
|---|---|---|
| Efficiency (AFUE) | 82 % | 82 % |
| Shipping weight | 512 lb | 584 lb |
| Dimensions (W x H x D) | 21" x 36-3/8 in. x 26-1/2 in. | 24-1/4" x 36-3/8 in. x 26-1/2 in. |
| Electrical | 120 V AC / 60 Hz / 1 phase, less than 12 A (15 A circuit recommended) | 120 V AC / 60 Hz / 1 phase, less than 12 A (15 A circuit recommended) |
| Fuel | Natural gas or propane | Natural gas or propane |
| Input (natural gas) | 187 MBH | 225 MBH |
| Input (propane) | 175 MBH | 210 MBH |
| Heating capacity (natural gas) | 153 MBH | 183 MBH |
| Heating capacity (propane) | 143 MBH | 171 MBH |
| Net AHRI steam rating (natural gas) | 115 MBH | 137 MBH |
| Net AHRI steam rating (propane) | 107 MBH | 128 MBH |
| Flue diameter | 7" | 7" |
| Connections | Return/supply 2-1/2 in. NPT; gas 1/2 in. NPT (75/112/150) or 3/4 in. NPT (187 MBH and larger) | Return/supply 2-1/2 in. NPT; gas 1/2 in. NPT (75/112/150) or 3/4 in. NPT (187 MBH and larger) |
| Control | Electronic low-water cut-off with 3/4 in. probe, pressure limit control, steam pressure gauge and glass water level gauge | Electronic low-water cut-off with 3/4 in. probe, pressure limit control, steam pressure gauge and glass water level gauge |
Published ratings: the Dunkirk PSB-6D is rated 187 MBH input, 153 MBH heating capacity and 82% AFUE; the Dunkirk PSB-7D is rated 225 MBH input, 183 MBH heating capacity and 82% AFUE. Dunkirk PSB-7D lists 38 MBH more input than Dunkirk PSB-6D (225 MBH against 187 MBH). Both list the same published AFUE of 82%.
Dunkirk PSB-7D lists 72 lb more shipping weight than Dunkirk PSB-6D (584 lb against 512 lb). The dimensions differs: the Dunkirk PSB-6D lists 21" x 36-3/8 in. x 26-1/2 in., while the Dunkirk PSB-7D lists 24-1/4" x 36-3/8 in. x 26-1/2 in.
Both records print the same AFUE (82%), electrical requirement (120 V AC / 60 Hz / 1 phase, less than 12 A (15 A circuit recommended)), fuel (Natural gas or propane) and flue diameter (7"), per the cited sources.
Dunkirk Boilers
The Dunkirk PSB-6D is a current cast-iron gas steam boiler: 187 MBH natural-gas input (175 MBH propane) for 153/143 MBH NG/LP heating capacity, a 115/107 MBH net AHRI steam rating (479/446 sq ft) at 82% AFUE, with a 7" flue and 512 lb shipping.
Dunkirk Boilers
The Dunkirk PSB-7D is a current cast-iron gas steam boiler: 225 MBH natural-gas input (210 MBH propane) for 183/171 MBH NG/LP heating capacity, a 137/128 MBH net AHRI steam rating (570/533 sq ft) at 82% AFUE, with a 7" flue and 584 lb shipping.
The Dunkirk PSB-7D lists 225 MBH, against 187 MBH on the Dunkirk PSB-6D, per the cited documentation.
Both list the same AFUE of 82%.
It ships at 584 lb against 512 lb for the Dunkirk PSB-6D, per the cited sources.
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.