Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The Royal CO-90 and CO-150 are the two smaller Royal combis in the same wall-hung cabinet at 95.2% AFUE. The CO-150 roughly doubles the combi's hot-water side — DHW input up from 90 to 150 MBH and flow from 2.5 to 3.7 GPM at a 70 °F rise — while central heating rises from 80 to 120 MBH input and heating capacity from 74 to 110 MBH.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Dunkirk Royal CO-90 | Dunkirk Royal CO-150 |
|---|---|---|
| Central-heating input, minimum | 9 MBH | 15 MBH |
| Central-heating input, maximum | 80 MBH | 120 MBH |
| DHW input, minimum | 9 MBH | 15 MBH |
| DHW input, maximum | 90 MBH | 150 MBH |
| DHW flow rate at 70 °F rise | 2.5 gpm | 3.7 gpm |
| AFUE | 95.2 % | 95.2 % |
| Heating capacity | 74 MBH | 110 MBH |
| Net AHRI water rating | 64 MBH | 96 MBH |
| Turndown | Up to 10:1 | Up to 10:1 |
| Dimensions (H x W x D) | 28.23" x 17.4" x 16.93" | 28.23" x 17.4" x 16.93" |
Both are wall-hung residential combis of Dunkirk's current Royal CO line on the same stainless steel water-tube heat exchanger platform: 95.2% AFUE, up to 10:1 turndown, the shared 28.23 x 17.4 x 16.93 in cabinet, and identical 3/4" NPT CH / 1/2" NPT DHW connections.
The official brochure table prints central-heating input of 9-80 MBH on the CO-90 and 15-120 MBH on the CO-150, with heating capacity rising from 74 to 110 MBH and the net AHRI water rating from 64 to 96 MBH. The DHW side is where the sizes separate: the CO-150's DHW input reaches 150 MBH against the CO-90's 90 MBH, lifting DHW flow at a 70 °F rise from 2.5 to 3.7 GPM.
The CO-90's lower minimum fire (9 MBH against 15 MBH on the CH side) tracks mild weather more closely in a low-load home, so the CO-150 earns its place through the heat-loss calculation and the household's simultaneous hot-water draws rather than through size alone.
Dunkirk Boilers
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.
Dunkirk Boilers
The Royal CO-150 is Dunkirk's 150 MBH-class wall-hung residential combi: 15 to 120 MBH central-heating input with DHW input from 15 to 150 MBH (3.7 GPM at a 70 °F rise), 95.2% AFUE, 110 MBH heating capacity and up to 10:1 turndown.
The official brochure prints 3.7 GPM against 2.5 GPM at a 70 °F rise, with DHW input of 150 MBH against 90 MBH.
Yes — all residential Royal sizes share the 28.23 x 17.4 x 16.93 in wall-hung cabinet.
Size from a licensed heat-loss calculation and the hot-water draw pattern: the CO-90 fires down to 9 MBH and covers modest loads, while the CO-150 adds DHW and heating headroom.
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.