Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The ES25 is one size up from the ES24 in the fixed-input ES2 cast-iron line: input grows from 105 to 140 MBH, DOE heating capacity from 89 to 119 MBH and the net AHRI rating from 77 to 103 MBH — all still at 85% AFUE, with the draft hood stepping from 5" to 6" and shipping weight from 304 to 357 lb.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Burnham ES2 ES24 | Burnham ES2 ES25 |
|---|---|---|
| Input | 105 MBH | 140 MBH |
| DOE heating capacity | 89 MBH | 119 MBH |
| Net AHRI water rating | 77 MBH | 103 MBH |
| Efficiency (AFUE) | 85 % | 85 % |
| Venting | Category I natural draft — draft hood into an existing lined chimney (Type B/L gas vent); 5" draft hood | Category I natural draft — draft hood into an existing lined chimney (Type B/L gas vent); 6" draft hood |
| Shipping weight | 304 lb | 357 lb |
| Gas connection | 1/2" NPT | 1/2" NPT |
| Supply/return connections | 1-1/4" NPT | 1-1/4" NPT |
| Maximum allowable working pressure (MAWP) | 50 psi | 50 psi |
| Electrical | 120 VAC, 60 Hz, 1-phase, 15 A | 120 VAC, 60 Hz, 1-phase, 15 A |
Both are non-condensing cast-iron ES2 boilers at 85% AFUE with fixed inputs, Category I draft-hood venting and the IQ Boiler Control System on natural or LP gas.
The ES25 fires a fixed 140 MBH (against 105 MBH on the ES24) for 119 MBH DOE heating capacity and a 103 MBH net AHRI water rating versus 89 and 77 MBH.
Physically the ES25 joins the 6" draft-hood group (shared with the ES26) — the ES24 uses 5" — and ships at 357 lb (284 lb empty) versus 304 lb (231 lb empty). Water connections (1-1/4" NPT) and gas (1/2" NPT) are unchanged, and both are rated 50 psi MAWP with a 30 psi shipped relief valve.
Burnham
The Burnham ES2 ES24 steps the cast-iron ES2 line to a fixed 105 MBH input: 89 MBH DOE heating capacity and a 77 MBH net AHRI rating at 85% AFUE, with a 5" draft hood for Category I chimney venting.
Burnham
The Burnham ES2 ES25 fires a fixed 140 MBH input for 119 MBH DOE heating capacity and a 103 MBH net AHRI rating at 85% AFUE — the first 6" draft-hood size of the non-condensing, Category I ES2 cast-iron line.
The ES25 and ES26 share the 6" draft hood; the ES24 uses 5" and the ES27/ES28 move to 7".
Fixed input rises from 105 to 140 MBH, DOE heating capacity from 89 to 119 MBH, net AHRI from 77 to 103 MBH, and shipping weight from 304 to 357 lb.
Yes — every ES2 model is rated 85% AFUE; the line is non-condensing.
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 8, 2026. Last updated September 8, 2026. Technical reviewer: not yet assigned.