Canada-wide gas boiler information · On-site service in Greater Vancouver, BC
Boilers.ca is a brand of ROMA Heating & Cooling · Licensed gas contractor LGA0202903
Comparison
Verdict in brief
The GV90+6 tops the line at 175 MBH input and 161 MBH DOE heating capacity against the +5's 140/130 MBH — both in the 37-3/4" cabinet, with the +6 at 91.0% AFUE and a 464 lb shipping weight.
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | Weil-McLain GV90+5 | Weil-McLain GV90+6 |
|---|---|---|
| Input, maximum | 140 MBH | 175 MBH |
| DOE heating capacity | 130 MBH | 161 MBH |
| Net AHRI water rating | 113 MBH | 140 MBH |
| Efficiency (AFUE) | 91.4 % | 91 % |
| Weight | 423 lb | 464 lb |
| Boiler water content | 6 gal | 6.9 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 boilers share the 37-3/4" Series 2 cabinet, 3" venting to 100 ft and 1" NPT supply and return connections with 1/2" NPT gas. The +6 steps input from 140 to 175 MBH, DOE heating capacity from 130 to 161 MBH and the net AHRI rating from 113 to 140 MBH.
Water content rises from 6.0 to 6.9 gallons and shipping weight from 423 to 464 lb — the +6 is the heaviest GV90+, so the floor and access route deserve planning. Its 91.0% AFUE is the lowest of the four ratings, all of which sit in the 91.0-91.9% band.
Both are heating-only cast iron boilers suited to high-temperature emitters like baseboard and radiators. The +6 earns its place when the calculated load approaches the +5's 130 MBH of output on a design day.
Weil-McLain
The GV90+5 is the first of the long-cabinet GV90+ sizes: 140 MBH input, 130 MBH DOE heating capacity and a 113 MBH net AHRI rating at 91.4% AFUE, in a 37-3/4" unit.
Weil-McLain
The GV90+6 is the largest GV90+ at 175 MBH input and 161 MBH DOE heating capacity — 91.0% AFUE in the 37-3/4" cabinet with 6.9 gallons of boiler water.
175 MBH input, 161 MBH DOE heating capacity, 140 MBH net AHRI and 91.0% AFUE.
Yes — 464 lb shipping against 423 lb, with water content up from 6.0 to 6.9 gallons, in the same 37-3/4" cabinet.
When the heat-loss calculation for a large home or light-commercial plant exceeds the +5's 130 MBH of DOE output.
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.