Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
Both the Dunkirk Q90-100 and the Dunkirk Q90-125 belong to the Dunkirk Boilers Q90 (Series 4 and Q90-200 Series II) line of condensing boilers. The Dunkirk Q90-100 is documented at 100 MBH input, 90 MBH heating capacity and 90% AFUE, while the Dunkirk Q90-125 is documented at 125 MBH input, 112.5 MBH heating capacity and 90% AFUE. Dunkirk Q90-125 lists 25 MBH more input than Dunkirk Q90-100 (125 MBH against 100 MBH). Both list the same published AFUE of 90%. Dunkirk Q90-125 lists 64 lb more shipping weight than Dunkirk Q90-100 (284 lb against 220 lb).
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Dunkirk Q90-100 | Dunkirk Q90-125 |
|---|---|---|
| Input | 100 MBH | 125 MBH |
| Heating capacity | 90 MBH | 112.5 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 | 284 lb |
| Net I=B=R rating | 78 MBH | 98 MBH |
| Flue | 2" | 2" CPVC & 3" PVC |
| 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 |
| Heat exchanger | Cast aluminium sections and push nipples | Cast aluminium monoblock |
| Warranty | 15-year limited heat exchanger warranty | 15-year limited heat exchanger warranty |
Published ratings: the Dunkirk Q90-100 is rated 100 MBH input, 90 MBH heating capacity and 90% AFUE; the Dunkirk Q90-125 is rated 125 MBH input, 112.5 MBH heating capacity and 90% AFUE. Dunkirk Q90-125 lists 25 MBH more input than Dunkirk Q90-100 (125 MBH against 100 MBH). Both list the same published AFUE of 90%.
Dunkirk Q90-125 lists 64 lb more shipping weight than Dunkirk Q90-100 (284 lb against 220 lb). The flue differs: the Dunkirk Q90-100 lists 2", while the Dunkirk Q90-125 lists 2" CPVC & 3" PVC. The connections differs: the Dunkirk Q90-100 lists Gas 1/2 in. IPS; supply & return 1-1/4 in. NPT; drain 3/4 in. NPT, while the Dunkirk Q90-125 lists Gas 1/2 in. IPS; supply & return 1-1/4 in. NPT. The heat exchanger differs: the Dunkirk Q90-100 lists Cast aluminium sections and push nipples, while the Dunkirk Q90-125 lists Cast aluminium monoblock.
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) and warranty (15-year limited heat exchanger warranty), per the cited sources.
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.
Dunkirk Boilers
The Dunkirk Q90-125 is a legacy condensing cast-aluminium gas boiler: 125 MBH input for 112.5 MBH heating capacity and a 98 MBH net I=B=R rating at 90% AFUE, with a 2" CPVC & 3" PVC flue arrangement and 284 lb shipping.
The Dunkirk Q90-125 lists 125 MBH, against 100 MBH on the Dunkirk Q90-100, per the cited documentation.
Both list the same AFUE of 90%.
It ships at 284 lb against 220 lb for the Dunkirk Q90-100, 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.