Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
Peerless Series GM GM-07 and Peerless Series GM GM-08 are two non-condensing boilers from the Peerless Boilers Series GM line. Published ratings: Peerless Series GM GM-07 at 342 MBH input, 275 MBH heating capacity and 80.3% thermal efficiency; Peerless Series GM GM-08 at 399 MBH input, 320 MBH heating capacity and 80.3% thermal efficiency. Peerless Series GM GM-08 lists 57 MBH more input than Peerless Series GM GM-07 (399 MBH against 342 MBH). Both list the same published thermal efficiency of 80.3%.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Peerless Series GM GM-07 | Peerless Series GM GM-08 |
|---|---|---|
| Input | 342 MBH | 399 MBH |
| Gross output | 275 MBH | 320 MBH |
| Net water rating | 239 MBH | 278 MBH |
| Thermal efficiency | 80.3 % | 80.3 % |
| 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 |
| Dimensions (A × B × C) | 25-3/4" × 26-1/4" × 35-1/4" | 25-3/4" × 29-3/4" × 35-1/4" |
| Fuel | Natural gas or LP gas | Natural gas or LP gas |
| Vent connector | 10" | 10" |
| Control | Spark pilot ignition | Spark pilot ignition |
Published ratings: the Peerless Series GM GM-07 is rated 342 MBH input, 275 MBH heating capacity and 80.3% thermal efficiency; the Peerless Series GM GM-08 is rated 399 MBH input, 320 MBH heating capacity and 80.3% thermal efficiency. Peerless Series GM GM-08 lists 57 MBH more input than Peerless Series GM GM-07 (399 MBH against 342 MBH). Both list the same published thermal efficiency of 80.3%.
The dimensions differs: the Peerless Series GM GM-07 lists 25-3/4" × 26-1/4" × 35-1/4", while the Peerless Series GM GM-08 lists 25-3/4" × 29-3/4" × 35-1/4".
Both records print the same thermal efficiency (80.3%), domestic-hot-water arrangement (Heating-only boiler — domestic hot water comes from a separate indirect tank or water heater), fuel (Natural gas or LP gas) and vent connector (10"), per the cited sources.
Peerless Boilers
The Peerless Series GM GM-07 is a current semi-commercial cast-iron gas boiler firing 342 MBH for 275 MBH gross output and a 239 MBH net water rating at 80.3% thermal efficiency, in a natural-draft chimney package sized for single, multiple or modular installations.
Peerless Boilers
The Peerless Series GM GM-08 is a current semi-commercial cast-iron gas boiler firing 399 MBH for 320 MBH gross output and a 278 MBH net water rating at 80.3% thermal efficiency, in a natural-draft chimney package sized for single, multiple or modular installations.
The Peerless Series GM GM-08 lists 399 MBH, against 342 MBH on the Peerless Series GM GM-07, per the cited documentation.
Both list the same thermal efficiency of 80.3%.
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.