Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The Weil-McLain EG-35 and Weil-McLain EG-40 are both non-condensing boilers in the Weil-McLain EG / EG Steam line. The Weil-McLain EG-35 is rated 100 MBH input, 85 MBH DOE heating capacity, water and 84% AFUE, water, and the Weil-McLain EG-40 is rated 125 MBH input, 106 MBH DOE heating capacity, water and 84% AFUE, water. Weil-McLain EG-40 lists 25 MBH more input than Weil-McLain EG-35 (125 MBH against 100 MBH). Both list the same published AFUE, water of 84%. Weil-McLain EG-40 lists 75 lb more shipping weight than Weil-McLain EG-35 (505 lb against 430 lb).
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Weil-McLain EG-35 | Weil-McLain EG-40 |
|---|---|---|
| Input, maximum | 100 MBH | 125 MBH |
| Boiler water content | 12.3 gal | 14.8 gal |
| Weight | 430 lb | 505 lb |
| Venting | Category I, B-vent — vertical vent only, natural draft with draft hood and automatic vent damper; 5" I.D. chimney x 20 ft | Category I, B-vent — vertical vent only, natural draft with draft hood and automatic vent damper; 6" I.D. chimney x 20 ft |
| Gas connection | 1/2" | 1/2" |
| DOE heating capacity, water | 85 MBH | 106 MBH |
| DOE heating capacity, steam | 82 MBH | 103 MBH |
| Net AHRI rating, water | 74 MBH | 92 MBH |
| Net AHRI rating, steam | 62 MBH | 77 MBH |
| Net AHRI steam rating, area | 258 sq ft | 321 sq ft |
| AFUE, water | 84 % | 84 % |
| AFUE, steam | 82 % | 82 % |
| Supply connection | 3" | 3" |
| Return connection | 2-1/2" | 2-1/2" |
| Relief valve | 3/4" tapping | 3/4" tapping |
| Steam-to-waterline content | 8.4 gal | 9.8 gal |
Published ratings: the Weil-McLain EG-35 is rated 100 MBH input, 85 MBH DOE heating capacity, water and 84% AFUE, water; the Weil-McLain EG-40 is rated 125 MBH input, 106 MBH DOE heating capacity, water and 84% AFUE, water. Weil-McLain EG-40 lists 25 MBH more input than Weil-McLain EG-35 (125 MBH against 100 MBH). Both list the same published AFUE, water of 84%.
Weil-McLain EG-40 lists 75 lb more shipping weight than Weil-McLain EG-35 (505 lb against 430 lb). The boiler water content differs: the Weil-McLain EG-35 lists 12.3 gal, while the Weil-McLain EG-40 lists 14.8 gal. The venting differs: the Weil-McLain EG-35 lists Category I, B-vent — vertical vent only, natural draft with draft hood and automatic vent damper; 5" I.D. chimney x 20 ft, while the Weil-McLain EG-40 lists Category I, B-vent — vertical vent only, natural draft with draft hood and automatic vent damper; 6" I.D. chimney x 20 ft. The steam-to-waterline content differs: the Weil-McLain EG-35 lists 8.4 gal, while the Weil-McLain EG-40 lists 9.8 gal.
Both records print the same gas connection (1/2"), AFUE, water (84%), AFUE, steam (82%) and supply connection (3"), per the cited sources.
Weil-McLain
The EG-35 steps the EG cast iron line to 100 MBH input with 85/82 MBH water/steam DOE heating capacity, 258 sq ft of steam coverage and the range's 84%/82% AFUE; discontinued in Canada, current in the US.
Weil-McLain
The EG-40 raises the EG line to 125 MBH input with 106/103 MBH water/steam DOE heating capacity, 321 sq ft of steam coverage and 84%/82% AFUE; discontinued in Canada, still sold in the US as EG Series 6 and Series 7.
The Weil-McLain EG-40 lists 125 MBH, against 100 MBH on the Weil-McLain EG-35, per the cited documentation.
Both list the same AFUE, water of 84%.
It ships at 505 lb against 430 lb for the Weil-McLain EG-35, per the cited sources.
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.