Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Dunkirk Boilers · Series
The Dunkirk PSB (Plymouth Steam Boiler) is the current cast-iron gas steam boiler line: seven sizes PSB-3D through PSB-9D with natural-gas inputs of 75 to 299 MBH (propane 70–280 MBH), net AHRI steam ratings of 47 to 184 MBH (195–766 sq ft), up to 82.7% AFUE and a probe-type low-water cut-off with pressure limit and gauge glass.
Series facts
Up to 82.7% AFUE per the product page and sell sheet (PSB-3D at 82.7%; the remaining sizes print 82.0%).
The PSB (Plymouth Steam Boiler) is documented on Dunkirk's current gas-steam-boiler page as an atmospheric cast-iron steam boiler with an AFUE as high as 82.7%. The sell sheet (240009797, 10/16/24) prints seven sizes with dual natural-gas/propane columns: PSB-3D (75/70 MBH input / 62/58 heating capacity / 47/44 net steam / 195/183 sq ft / 82.7% AFUE / 5 in. flue / 297 lb), PSB-4D (112/105 / 91/85 / 68/64 / 283/267 / 82.0% / 6 in. / 368 lb), PSB-5D (150/140 / 122/114 / 92/86 / 383/358 / 82.0% / 6 in. / 440 lb), PSB-6D (187/175 / 153/143 / 115/107 / 479/446 / 82.0% / 7 in. / 512 lb), PSB-7D (225/210 / 183/171 / 137/128 / 570/533 / 82.0% / 7 in. / 584 lb), PSB-8D (262/245 / 214/200 / 161/150 / 670/625 / 82.0% / 7 in. / 659 lb) and PSB-9D (299/280 / 245/229 / 184/172 / 766/717 / 82.0% / 7 in. / 736 lb).
The line connects on 2-1/2 in. NPT return/supply tappings with a 1/2 in. NPT gas inlet on the 75/112/150 sizes and 3/4 in. NPT on 187 MBH and larger, and runs on 120 V AC at less than 12 A. The control module provides an electronic low-water cut-off with a 3/4 in. probe, pressure limit control, steam pressure gauge and glass water level gauge; the combustion train uses titanium composite burners, an intermittent pilot control and an integral draft diverter, with flame roll-out and blocked-vent safety shut-offs.
Boilers.ca records the series and its seven printed sizes; the Dunkirk nav card label 'PSB Series 2' differs from the current documents' Series 6/PSB naming, and the record follows the current sell sheet and manual. No official Canadian-sales statement was found, so canadianStatus stays 'unknown', and gas, combustion and steam work belongs with a licensed contractor against the PSB Steam Boiler Manual Rev. C.
Highlights
Models
One canonical page per model with input, output and efficiency kept separate.
Dunkirk Boilers
The Dunkirk PSB-3D is a current cast-iron gas steam boiler: 75 MBH natural-gas input (70 MBH propane) for 62/58 MBH NG/LP heating capacity, a 47/44 MBH net AHRI steam rating (195/183 sq ft) at 82.7% AFUE, with a 5" flue and 297 lb shipping.
Dunkirk Boilers
The Dunkirk PSB-4D is a current cast-iron gas steam boiler: 112 MBH natural-gas input (105 MBH propane) for 91/85 MBH NG/LP heating capacity, a 68/64 MBH net AHRI steam rating (283/267 sq ft) at 82% AFUE, with a 6" flue and 368 lb shipping.
Dunkirk Boilers
The Dunkirk PSB-5D is a current cast-iron gas steam boiler: 150 MBH natural-gas input (140 MBH propane) for 122/114 MBH NG/LP heating capacity, a 92/86 MBH net AHRI steam rating (383/358 sq ft) at 82% AFUE, with a 6" flue and 440 lb shipping.
Dunkirk Boilers
The Dunkirk PSB-6D is a current cast-iron gas steam boiler: 187 MBH natural-gas input (175 MBH propane) for 153/143 MBH NG/LP heating capacity, a 115/107 MBH net AHRI steam rating (479/446 sq ft) at 82% AFUE, with a 7" flue and 512 lb shipping.
Dunkirk Boilers
The Dunkirk PSB-7D is a current cast-iron gas steam boiler: 225 MBH natural-gas input (210 MBH propane) for 183/171 MBH NG/LP heating capacity, a 137/128 MBH net AHRI steam rating (570/533 sq ft) at 82% AFUE, with a 7" flue and 584 lb shipping.
Dunkirk Boilers
The Dunkirk PSB-8D is a current cast-iron gas steam boiler: 262 MBH natural-gas input (245 MBH propane) for 214/200 MBH NG/LP heating capacity, a 161/150 MBH net AHRI steam rating (670/625 sq ft) at 82% AFUE, with a 7" flue and 659 lb shipping.
Dunkirk Boilers
The Dunkirk PSB-9D is a current cast-iron gas steam boiler: 299 MBH natural-gas input (280 MBH propane) for 245/229 MBH NG/LP heating capacity, a 184/172 MBH net AHRI steam rating (766/717 sq ft) at 82% AFUE, with a 7" flue and 736 lb shipping.
| Specification | Dunkirk PSB-3D | Dunkirk PSB-4D | Dunkirk PSB-5D | Dunkirk PSB-6D | Dunkirk PSB-7D | Dunkirk PSB-8D | Dunkirk PSB-9D |
|---|---|---|---|---|---|---|---|
| input-min | — | — | — | — | — | — | — |
| input-max | — | — | — | — | — | — | — |
| output-max | — | — | — | — | — | — | — |
| Efficiency (AFUE) | 82.7 % | 82 % | 82 % | 82 % | 82 % | 82 % | 82 % |
| turndown | — | — | — | — | — | — | — |
| vent-max-3 | — | — | — | — | — | — | — |
| vent-max-2 | — | — | — | — | — | — | — |
| Shipping weight | 297 lb | 368 lb | 440 lb | 512 lb | 584 lb | 659 lb | 736 lb |
Read the full comparison: Dunkirk PSB-3D vs Dunkirk PSB-4D →
Read the full comparison: Dunkirk PSB-4D vs Dunkirk PSB-5D →
Read the full comparison: Dunkirk PSB-5D vs Dunkirk PSB-6D →
Read the full comparison: Dunkirk PSB-6D vs Dunkirk PSB-7D →
Error codes and alerts
No alerts documented for this series yet.
Manuals
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.
Services for Dunkirk Boilers boilers
Seven: PSB-3D through PSB-9D, with natural-gas inputs of 75 to 299 MBH and propane inputs of 70 to 280 MBH per the official sell sheet.
Up to 82.7% AFUE (PSB-3D) with the remaining sizes at 82.0%, per the sell sheet and product page.
Steam — the PSB (Plymouth Steam Boiler) is a cast-iron gas steam boiler with an electronic low-water cut-off, pressure limit and gauge glass, vented vertically with an integral draft diverter.
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.
Sources and verification
Facts checked September 9, 2026. Last updated September 9, 2026. Technical reviewer: not yet assigned.