Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
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Comparison
Verdict in brief
The GV90+3 and GV90+4 share the 30-3/4" cabinet, 3" venting and 91%-plus AFUE of the Series 2 line; the +4 steps input from 70 to 105 MBH and DOE heating capacity from 65 to 97 MBH, while efficiency drops slightly from 91.9% to 91.2% AFUE.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Weil-McLain GV90+3 | Weil-McLain GV90+4 |
|---|---|---|
| Input, maximum | 70 MBH | 105 MBH |
| DOE heating capacity | 65 MBH | 97 MBH |
| Net AHRI water rating | 57 MBH | 84 MBH |
| Efficiency (AFUE) | 91.9 % | 91.2 % |
| Weight | 313 lb | 353 lb |
| Boiler water content | 3.8 gal | 4.7 gal |
| Venting | 3" PVC, CPVC, polypropylene or stainless steel (Category IV); 3" pipe on all GV90+ sizes | 3" PVC, CPVC, polypropylene or stainless steel (Category IV); 3" pipe on all GV90+ sizes |
Both are Series 2 GV90+ high-efficiency cast iron boilers with the stainless steel secondary heat exchanger, built-in low water cut-off, 3" Category IV venting to 100 ft, and the same 30-3/4" cabinet length.
The GV90+4 steps input from 70 to 105 MBH, DOE heating capacity from 65 to 97 MBH and the net AHRI rating from 57 to 84 MBH (manual figures), while its 91.2% AFUE sits just under the +3's 91.9% — the top rating in the line. Water content grows from 3.8 to 4.7 gallons and shipping weight from 313 to 353 lb.
Both connect with 1" NPT supply and return fittings and 1/2" NPT gas, and both are heating-only boilers matched with an indirect tank for domestic hot water. The heat-loss calculation decides between the 65 and 97 MBH output ceilings.
Weil-McLain
The GV90+3 is the smallest Series 2 GV90+: 70 MBH input, 65 MBH DOE heating capacity and a 91.9% AFUE rating — the highest in the line — from the cast iron boiler with stainless steel secondary heat exchanger.
Weil-McLain
The GV90+4 steps the cast iron line to 105 MBH input and 97 MBH DOE heating capacity at 91.2% AFUE, keeping the 30-3/4" cabinet length with 4.7 gallons of boiler water.
The GV90+3 at 91.9% AFUE; the GV90+4 rates 91.2%. Both exceed the ENERGY STAR threshold cited in Weil-McLain's brochure.
The cabinet length is the same at 30-3/4", but the +4 is heavier (353 lb shipping) and holds more water (4.7 versus 3.8 gallons).
When the heat-loss calculation exceeds the +3's 65 MBH of DOE output on a design day.
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 7, 2026. Last updated September 7, 2026. Technical reviewer: not yet assigned.