Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The Dunkirk Q90-75 and Dunkirk Q90-100 are both condensing boilers in the Dunkirk Boilers Q90 (Series 4 and Q90-200 Series II) line. The Dunkirk Q90-75 is rated 75 MBH input, 68 MBH heating capacity and 90% AFUE, and the Dunkirk Q90-100 is rated 100 MBH input, 90 MBH heating capacity and 90% AFUE. Dunkirk Q90-100 lists 25 MBH more input than Dunkirk Q90-75 (100 MBH against 75 MBH). Both list the same published AFUE of 90%. Both list the same published shipping weight of 220 lb.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Dunkirk Q90-75 | Dunkirk Q90-100 |
|---|---|---|
| Input | 75 MBH | 100 MBH |
| Heating capacity | 68 MBH | 90 MBH |
| Efficiency (AFUE) | 90 % | 90 % |
| 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 |
| Package shipping weight | 220 lb | 220 lb |
| Net I=B=R rating | 59 MBH | 78 MBH |
| Flue | 2" | 2" |
| Connections | Gas 1/2 in. IPS; supply & return 1-1/4 in. NPT; drain 3/4 in. NPT | Gas 1/2 in. IPS; supply & return 1-1/4 in. NPT; drain 3/4 in. NPT |
| Heat exchanger | Cast aluminium sections and push nipples | Cast aluminium sections and push nipples |
| Warranty | 15-year limited heat exchanger warranty | 15-year limited heat exchanger warranty |
Published ratings: the Dunkirk Q90-75 is rated 75 MBH input, 68 MBH heating capacity and 90% AFUE; the Dunkirk Q90-100 is rated 100 MBH input, 90 MBH heating capacity and 90% AFUE. Dunkirk Q90-100 lists 25 MBH more input than Dunkirk Q90-75 (100 MBH against 75 MBH). Both list the same published AFUE of 90%.
Both records print the same AFUE (90%), domestic-hot-water arrangement (Heating-only boiler — domestic hot water comes from a separate indirect tank or water heater), shipping weight (220 lb) and flue (2"), per the cited sources.
Dunkirk Boilers
The Dunkirk Q90-75 is a legacy condensing cast-aluminium gas boiler: 75 MBH input for 68 MBH heating capacity and a 59 MBH net I=B=R rating at 90% AFUE, with a 2" flue arrangement and 220 lb shipping.
Dunkirk Boilers
The Dunkirk Q90-100 is a legacy condensing cast-aluminium gas boiler: 100 MBH input for 90 MBH heating capacity and a 78 MBH net I=B=R rating at 90% AFUE, with a 2" flue arrangement and 220 lb shipping.
The Dunkirk Q90-100 lists 100 MBH, against 75 MBH on the Dunkirk Q90-75, per the cited documentation.
Both list the same AFUE of 90%.
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.