Dunkirk Boilers · Royal (CO/CH)
Dunkirk Royal CO-90
The Royal CO-90 is Dunkirk's 90 MBH-class wall-hung residential combi: 9 to 80 MBH central-heating input with DHW input from 9 to 90 MBH (2.5 GPM at a 70 °F rise), 95.2% AFUE, 74 MBH heating capacity and up to 10:1 turndown.
Key figures
- Max input
- 80 MBH
- Max CSA output
- —
- AFUE
- 95.2 %
- Min input
- 9 MBH
Input is gas energy consumed; output is heat delivered. Never size from input alone.
Dunkirk Royal CO-90 in practice
The Royal CO-90 is the 90 MBH-class combi of Dunkirk's current Royal CO residential line — the official page describes the CO (Combi) models as three sizes from 80,000 to 200,000 BTU/hr input producing domestic hot water along with central heating in one appliance, removing the need for a separate water heater. The brochure table prints 9 to 80 MBH central-heating input with DHW input of 9 to 90 MBH and 2.5 GPM of DHW flow at a 70 °F rise, at 95.2% AFUE with 74 MBH heating capacity and a 64 MBH net AHRI water rating.
It is a wall-hung condensing design on the next-generation enhanced stainless steel water-tube heat exchanger with up to 10:1 turndown, twin-pipe direct venting (the included 3-in-1 adjustable connector accepts PVC, CPVC, polypropylene or stainless steel; flue 3" with a 2" reducer; direct venting up to 150 ft per the page copy) and 3/4" NPT CH connections with 1/2" NPT DHW connections and 3/4" NPT gas. All residential Royal sizes share the 28.23" x 17.4" x 16.93" wall-hung cabinet at under 101 lb per the page copy.
Dunkirk prices the residential Royal line for homes rather than plant rooms: ENERGY STAR certified at 95.2% AFUE with cascade control to 16 boilers, a control display settable to 18 languages, and a 10-year heat exchanger / 5-year parts limited warranty (residential). Ratings on this record are the US-market figures Dunkirk prints; Boilers.ca found no official Canadian rating listings, so canadianStatus stays 'unknown'. Gas work belongs with a licensed contractor against the residential IOM (E93.1907.035.915.C).
Best suited to
- Homes whose heat-loss calculation and hot-water draws fit the 90 MBH-class combi
- Households replacing a boiler plus separate hot-water tank with one wall-hung appliance
- Wall-hung installations on the shared 28.23 x 17.4 x 16.93 in Royal cabinet
Applicability and support
- Model number
- CO-90
- Canadian availability
- unknown
- Production status
- current
- ROMA supplies
- Confirmed at consultation
- ROMA services
- Confirmed at consultation
- Warranty
- Series terms
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 | ||
| Central-heating input, minimum | 9 MBH | CH input minimum in MBH as printed in the official Royal residential brochure table. |
| Central-heating input, maximum | 80 MBH | CH input maximum in MBH as printed in the official Royal residential brochure table. |
| Output | ||
| Heating capacity | 74 MBH | Heating capacity in MBH as printed in the official Royal residential brochure table. |
| Net AHRI water rating | 64 MBH | Net AHRI water rating in MBH as printed in the official Royal residential brochure table. |
| Efficiency | ||
| AFUE | 95.2 % | 95.2% AFUE as printed for every residential Royal model in the official brochure table and on the product pages. |
| Domestic hot water | ||
| DHW input, minimum | 9 MBH | DHW input minimum in MBH as printed in the official Royal residential brochure table. |
| DHW input, maximum | 90 MBH | DHW input maximum in MBH as printed in the official Royal residential brochure table. |
| DHW flow rate at 70 °F rise | 2.5 gpm | Domestic hot water flow at a 70 °F temperature rise as printed in the official Royal residential brochure table. |
| Venting and air | ||
| Venting | Twin-pipe direct vent with the included 3-in-1 adjustable boiler vent connector | Venting approved in PVC, CPVC, polypropylene and stainless steel; flue 3" (2" with reducer) per the residential brochure; direct venting up to 150 ft per the page copy. Gas work belongs with a licensed contractor. |
| Physical and connections | ||
| Dimensions (H x W x D) | 28.23" x 17.4" x 16.93" | Brochure callouts for the wall-hung cabinet; the combi models add a plate on the front, per the research notes. |
| Heat exchanger | Next-generation enhanced stainless steel water-tube heat exchanger | As printed on the official pages; the commercial sizes use the DUO Power water-tube heat exchanger. |
| Burner | Stainless steel pre-mix burner (BlueJet) | BlueJet burner improves flame stability and reduces NOx, per the brochure. |
| Electrical | ||
| Power supply | 120 V ac, 60 Hz, 1 phase; 12 A minimum size circuit (15 A recommended) | As printed in the official Royal residential brochure. |
| Operating limits and other | ||
| Connections | CH supply/return 3/4" NPT; DHW supply/return 1/2" NPT; gas 3/4" NPT; condensate flexible hose 1.06" OD | Connection sizes per the connection table in the official Royal residential brochure. |
| Fuel | Natural gas or propane | Natural gas is the factory configuration; the official pages state the boiler is easily converted to propane (LP). |
| Turndown | Up to 10:1 | Up to 10:1 turndown as printed on the official product pages. |
| Control | Intuitive control with cascade to 16 boilers, 0-10 V and Modbus | Built-in cascade control for up to 16 boilers; display settable to 1 of 18 languages; 0-10 Volts equipped and BMS Modbus standard, per the brochure. |
| Warranty | 10-year heat exchanger and 5-year parts limited warranty (residential) | As printed on the official Royal CO and CH residential product pages. |
Manuals
- Royal Series Residential Boiler Manual Rev. C EN (E93.1907.035.915.C)E93.1907.035.915.C (Rev. C) · 2026-03
- Royal Series Residential Boiler Brochure (240013861 Rev. 08/12/26)240013861 Rev. 08/12/26
Alerts documented for this model
Frequently asked questions
Is the Royal CO-90 a combi boiler?
Yes — the CO models combine central heating with on-demand domestic hot water (DHW input 9 to 90 MBH, up to 2.5 GPM at a 70 °F rise), removing the separate water heater.
What is the Royal CO-90's efficiency rating?
95.2% AFUE, as printed for every residential Royal model in the official brochure table and on the product pages.
Where does the CO-90 sit in the Royal CO range?
It is the 90 MBH-class size: central heating runs 9 to 80 MBH input and DHW 9 to 90 MBH, above the smaller CO sizes and below the CO-200.
Questions about the Dunkirk Royal CO-90?
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
- Dunkirk Royal CO-90 vs CO-150Comparison
- Dunkirk Royal CO-90 vs CH-80Comparison
- Dunkirk Royal CO-150Same series
- Dunkirk Royal CO-200Same series
- Dunkirk Royal CH-80Same series
- Dunkirk Royal CH-100Same series
- Dunkirk Royal CH-120Same series
- Dunkirk Royal CH-150Same series
- Dunkirk Royal CH-180Same series
- Royal (CO/CH) series hub
- Buying guide
Sources and verification
- Dunkirk — Royal CO combi product page · accessed September 9, 2026
- Royal Series Residential Boiler Brochure (240013861 Rev. 08/12/26) · accessed September 9, 2026
- Royal Series Residential Boiler Manual Rev. C EN (E93.1907.035.915.C) · accessed September 9, 2026
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.