Dunkirk Boilers · Q90 (Series 4 and Q90-200 Series II)
Dunkirk Q90-75
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.
Key figures
- Max input
- —
- Max CSA output
- —
- AFUE
- 90 %
- Min input
- —
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Dunkirk Q90-75 in practice
The Q90-75 is one of the three Q90 Series 4 sizes (50, 75 and 100 MBH) in Dunkirk's legacy condensing line. Its spec sheet ratings row prints 75 MBH input, 68 MBH heating capacity and a 59 MBH net I=B=R rating (1.15 allowance) at 90% AFUE, with a 2" flue arrangement and 220 lb package shipping weight.
The Series 4 uses a cast aluminium sectional heat exchanger with push nipples, hot surface ignition (HSI) and a Hydrolevel combination high-limit/low-water cut-off control with boiler water temperature reset, sealed-combustion direct venting with printed PVC vent-length limits, and a stainless steel premix burner. Both spec sheets print a 15-year limited heat exchanger warranty, and the boilers run on natural or propane gas.
Neither Q90 page appears in Dunkirk's current category navigation and both show zero current documents (62 and 38 archived respectively), so Boilers.ca records the models as discontinued for identification and service planning. No official Canadian-sales statement was found, so canadianStatus stays 'unknown'; gas and combustion work belongs with a licensed contractor against the archived IOM for the specific series.
Best suited to
- Owners documenting an installed Q90-75 against the official spec sheet
- Service planning for the Series 4 HSI/Hydrolevel control platform
- Legacy replacement research in the 90% AFUE condensing class
Applicability and support
- Model number
- Q90-75
- Canadian availability
- unknown
- Production status
- discontinued
- ROMA supplies
- Confirmed at consultation
- ROMA services
- Confirmed at consultation
- Warranty
- Not verified
Where ROMA provides on-site service
On-site service is currently offered in Greater Vancouver, BC, including Vancouver, Burnaby, Richmond, Surrey, Coquitlam, North Vancouver, West Vancouver, New Westminster, Port Coquitlam, Port Moody, Delta, Langley, Maple Ridge, Abbotsford, Chilliwack, White Rock, Pitt Meadows, Tsawwassen, Anmore, Lions Bay, Belcarra, Bowen Island, Mission. Everything else on this site is reference information you can use anywhere in Canada.
Specifications
Published specifications
Values as published by Dunkirk Boilers. Units are shown with every value; notes flag conflicting sources or missing figures.
| Specification | Value | Note |
|---|---|---|
| Input | ||
| Input | 75 MBH | Input per the official spec sheet ratings table (sea level through 2,000 ft). |
| Output | ||
| Heating capacity | 68 MBH | Heating capacity per the official spec sheet (DOE test procedures). |
| Net I=B=R rating | 59 MBH | Net I=B=R rating based on an allowance of 1.15 per the spec sheet. |
| Efficiency | ||
| Efficiency (AFUE) | 90 % | 90% AFUE per the spec sheet and both Q90 product pages; the lines are ENERGY STAR rated. |
| Domestic hot water | ||
| Domestic hot water | Heating-only boiler — domestic hot water comes from a separate indirect tank or water heater | |
| Venting and air | ||
| Flue | 2" | Flue outlet diameter per the Q90 Series 4 spec sheet; sealed-combustion direct vent with 2 in. or 3 in. PVC venting limits printed in the sheet. |
| Physical and connections | ||
| Package shipping weight | 220 lb | Shipping weight per the spec sheet. |
| Connections | Gas 1/2 in. IPS; supply & return 1-1/4 in. NPT; drain 3/4 in. NPT | Per the Q90 Series 4 spec sheet connections block. |
| Heat exchanger | Cast aluminium sections and push nipples | Per the official spec sheets; the lines are the Dunkirk twins of the Utica UB90 family. |
| Operating limits and other | ||
| Warranty | 15-year limited heat exchanger warranty | As printed on both spec sheets. |
Manuals
- Q90-100 Series IV Spec Sheet Rev. 1.0 (PN 240005687, 10/05)240005687 Rev. 1.0 · 2005-10
- Q90 Series 4 IOM Rev. D (240010121)240010121 Rev. D
Alerts documented for this model
None documented yet.
Frequently asked questions
What are the Q90-75's ratings?
75 MBH input, 68 MBH heating capacity and a 59 MBH net I=B=R rating at 90% AFUE per the official spec sheet.
Is the Q90-75 still sold?
No — neither Q90 page shows current documents (all literature is archived), so Boilers.ca records the line as discontinued.
What heat exchanger does the Q90-75 use?
Cast aluminium sections and push nipples per the Q90 Series 4 spec sheet.
Questions about the Dunkirk Q90-75?
Describe what the boiler is doing and get a straight answer about the next step.
On-site service in Greater Vancouver, BC. ROMA lists “Open 7 days” on its site; call to confirm same-day availability.
Compare and explore
Sources and verification
- Dunkirk — Q90 Series 4 product page (0 current documents) · accessed September 9, 2026
- Dunkirk — Q90-100 Series IV Spec Sheet Rev. 1.0 (archived) · accessed September 9, 2026
- Dunkirk — Q90 Series 4 IOM Rev. D (archived) · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.