Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
Dunkirk WPSB-5D and Dunkirk WPSB-6D are two non-condensing boilers from the Dunkirk Boilers WPSB Series 4 line. The Dunkirk WPSB-5D is documented at 150 MBH input, 126 MBH heating capacity and 84.1% AFUE, while the Dunkirk WPSB-6D is documented at 187.5 MBH input, 157 MBH heating capacity and 84.1% AFUE. Dunkirk WPSB-6D lists 37.5 MBH more input than Dunkirk WPSB-5D (187.5 MBH against 150 MBH). Both list the same published AFUE of 84.1%. Dunkirk WPSB-6D lists 81 lb more shipping weight than Dunkirk WPSB-5D (534 lb against 453 lb).
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Dunkirk WPSB-5D | Dunkirk WPSB-6D |
|---|---|---|
| Input | 150 MBH | 187.5 MBH |
| Heating capacity | 126 MBH | 157 MBH |
| Net AHRI water rating | 110 MBH | 137 MBH |
| Efficiency (AFUE) | 84.1 % | 84.1 % |
| Domestic hot water | Heating-only boiler — domestic hot water comes from a separate indirect tank or water heater | Heating-only boiler — domestic hot water comes from a separate indirect tank or water heater |
| Boiler water content | 9.9 gal | 11.7 gal |
| Shipping weight | 453 lb | 534 lb |
| Dimensions | 17-3/4" wide x 36-3/8 in. high x 26-1/2 in. deep | 21" wide x 36-3/8 in. high x 26-1/2 in. deep |
| Gas connection | 1/2 in. NPT gas inlet; 1-1/4 in. water return/supply (all models). | 1/2 in. NPT gas inlet; 1-1/4 in. water return/supply (all models). |
| 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 |
Published ratings: the Dunkirk WPSB-5D is rated 150 MBH input, 126 MBH heating capacity and 84.1% AFUE; the Dunkirk WPSB-6D is rated 187.5 MBH input, 157 MBH heating capacity and 84.1% AFUE. Dunkirk WPSB-6D lists 37.5 MBH more input than Dunkirk WPSB-5D (187.5 MBH against 150 MBH). Both list the same published AFUE of 84.1%.
Dunkirk WPSB-6D lists 81 lb more shipping weight than Dunkirk WPSB-5D (534 lb against 453 lb). The boiler water content differs: the Dunkirk WPSB-5D lists 9.9 gal, while the Dunkirk WPSB-6D lists 11.7 gal. The dimensions differs: the Dunkirk WPSB-5D lists 17-3/4" wide x 36-3/8 in. high x 26-1/2 in. deep, while the Dunkirk WPSB-6D lists 21" wide x 36-3/8 in. high x 26-1/2 in. deep.
Both records print the same AFUE (84.1%), domestic-hot-water arrangement (Heating-only boiler — domestic hot water comes from a separate indirect tank or water heater), gas connection (1/2 in. NPT gas inlet; 1-1/4 in. water return/supply (all models).) and electrical requirement (120 V AC / 60 Hz / 1 phase, less than 12 A (15 A circuit recommended)), per the cited sources.
Dunkirk Boilers
The Dunkirk WPSB-5D is a current atmospheric cast-iron gas water boiler: 150 MBH natural-gas input (propane 140 MBH) for 126 MBH heating capacity and a 110 MBH net AHRI water rating at 84.1% AFUE, with 9.9 gallons of water content and a Fuel Smart Hydrostat control.
Dunkirk Boilers
The Dunkirk WPSB-6D is a current atmospheric cast-iron gas water boiler: 187.5 MBH natural-gas input (propane 175 MBH) for 157 MBH heating capacity and a 137 MBH net AHRI water rating at 84.1% AFUE, with 11.7 gallons of water content and a Fuel Smart Hydrostat control.
The Dunkirk WPSB-6D lists 187.5 MBH, against 150 MBH on the Dunkirk WPSB-5D, per the cited documentation.
Both list the same AFUE of 84.1%.
It ships at 534 lb against 453 lb for the Dunkirk WPSB-5D, 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.