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
Dunkirk WPSB-4D and Dunkirk WPSB-5D are two non-condensing boilers from the Dunkirk Boilers WPSB Series 4 line. The Dunkirk WPSB-4D is documented at 112.5 MBH input, 94 MBH heating capacity and 84% AFUE, while the Dunkirk WPSB-5D is documented at 150 MBH input, 126 MBH heating capacity and 84.1% AFUE. Dunkirk WPSB-5D lists 37.5 MBH more input than Dunkirk WPSB-4D (150 MBH against 112.5 MBH). Dunkirk WPSB-5D carries the higher published AFUE at 84.1%, against 84%. Dunkirk WPSB-5D lists 76 lb more shipping weight than Dunkirk WPSB-4D (453 lb against 377 lb).
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Dunkirk WPSB-4D | Dunkirk WPSB-5D |
|---|---|---|
| Input | 112.5 MBH | 150 MBH |
| Heating capacity | 94 MBH | 126 MBH |
| Net AHRI water rating | 82 MBH | 110 MBH |
| Efficiency (AFUE) | 84 % | 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 | 8.1 gal | 9.9 gal |
| Shipping weight | 377 lb | 453 lb |
| Dimensions | 14-1/2" wide x 36-3/8 in. high x 26-1/2 in. deep | 17-3/4" 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-4D is rated 112.5 MBH input, 94 MBH heating capacity and 84% AFUE; the Dunkirk WPSB-5D is rated 150 MBH input, 126 MBH heating capacity and 84.1% AFUE. Dunkirk WPSB-5D lists 37.5 MBH more input than Dunkirk WPSB-4D (150 MBH against 112.5 MBH). Dunkirk WPSB-5D carries the higher published AFUE at 84.1%, against 84%.
Dunkirk WPSB-5D lists 76 lb more shipping weight than Dunkirk WPSB-4D (453 lb against 377 lb). The boiler water content differs: the Dunkirk WPSB-4D lists 8.1 gal, while the Dunkirk WPSB-5D lists 9.9 gal. The dimensions differs: the Dunkirk WPSB-4D lists 14-1/2" wide x 36-3/8 in. high x 26-1/2 in. deep, while the Dunkirk WPSB-5D lists 17-3/4" wide x 36-3/8 in. high x 26-1/2 in. deep.
Both records print the same 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).), electrical requirement (120 V AC / 60 Hz / 1 phase, less than 12 A (15 A circuit recommended)) and fuel (Natural gas or propane), per the cited sources.
Dunkirk Boilers
The Dunkirk WPSB-4D is a current atmospheric cast-iron gas water boiler: 112.5 MBH natural-gas input (propane 105 MBH) for 94 MBH heating capacity and a 82 MBH net AHRI water rating at 84% AFUE, with 8.1 gallons of water content and a Fuel Smart Hydrostat control.
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.
The Dunkirk WPSB-5D lists 150 MBH, against 112.5 MBH on the Dunkirk WPSB-4D, per the cited documentation.
The Dunkirk WPSB-5D carries the higher published AFUE at 84.1%, against 84%.
It ships at 453 lb against 377 lb for the Dunkirk WPSB-4D, 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.