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
Both the U.S. Boiler Company K2WT-100B and the U.S. Boiler Company K2WT-120B belong to the U.S. Boiler Company K2 line of condensing boilers. The U.S. Boiler Company K2WT-100B is documented at 10–100 MBH input, 94 MBH heating capacity and 95% AFUE, while the U.S. Boiler Company K2WT-120B is documented at 12–120 MBH input, 112 MBH heating capacity and 95% AFUE. U.S. Boiler Company K2WT-120B lists 20 MBH more input than U.S. Boiler Company K2WT-100B (120 MBH against 100 MBH). Both list the same published AFUE of 95%. U.S. Boiler Company K2WT-120B lists 3 lb more shipping weight than U.S. Boiler Company K2WT-100B (105 lb against 102 lb).
Published manufacturer figures. Input and output are kept separate; blanks mean the manufacturer did not publish that value.
| Specification | U.S. Boiler Company K2WT-100B | U.S. Boiler Company K2WT-120B |
|---|---|---|
| Input, minimum | 10 MBH | 12 MBH |
| Input, maximum | 100 MBH | 120 MBH |
| DOE heating capacity | 94 MBH | 112 MBH |
| Net AHRI water rating | 82 MBH | 97 MBH |
| Efficiency (AFUE) | 95 % | 95 % |
| 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 |
| Approx. net weight | 102 lb | 105 lb |
| Dimensions (A × B × C) | 16-3/16" × 3" × 7-7/16" (A × B × C) | 16-3/16" × 3" × 7-7/16" (A × B × C) |
| Venting | Direct vent, sealed combustion; universal connection for CPVC/PVC, polypropylene and stainless steel | Direct vent, sealed combustion; universal connection for CPVC/PVC, polypropylene and stainless steel |
| Supply/return connections | 1" NPT supply and 1" NPT return | 1" NPT supply and 1" NPT return |
| Gas connection | 1/2" gas line per the dimension drawing | 1/2" gas line per the dimension drawing |
| Control | Sage2.3 Control System with LCD touch screen | Sage2.3 Control System with LCD touch screen |
| Fuel | Natural gas (LP conversion kit sold separately) | Natural gas (LP conversion kit sold separately) |
| Vent size | 2" or 3" | 3" |
Published ratings: the U.S. Boiler Company K2WT-100B is rated 10–100 MBH input, 94 MBH heating capacity and 95% AFUE; the U.S. Boiler Company K2WT-120B is rated 12–120 MBH input, 112 MBH heating capacity and 95% AFUE. U.S. Boiler Company K2WT-120B lists 20 MBH more input than U.S. Boiler Company K2WT-100B (120 MBH against 100 MBH). Both list the same published AFUE of 95%.
U.S. Boiler Company K2WT-120B lists 3 lb more shipping weight than U.S. Boiler Company K2WT-100B (105 lb against 102 lb). The vent size differs: the U.S. Boiler Company K2WT-100B lists 2" or 3", while the U.S. Boiler Company K2WT-120B lists 3".
Both records print the same AFUE (95%), domestic-hot-water arrangement (Heating-only boiler — domestic hot water comes from a separate indirect tank or water heater), dimensions (16-3/16" × 3" × 7-7/16" (A × B × C)) and venting (Direct vent, sealed combustion; universal connection for CPVC/PVC, polypropylene and stainless steel), per the cited sources.
U.S. Boiler Company
The U.S. Boiler Company K2WT-100B is the second size, keeping the 2-inch vent option: 10–100 MBH input with 94 MBH DOE heating capacity and a 82 MBH net AHRI water rating at 95% AFUE on the K2 condensing platform.
U.S. Boiler Company
The U.S. Boiler Company K2WT-120B is the last size in the compact 16-3/16-inch-wide cabinet: 12–120 MBH input with 112 MBH DOE heating capacity and a 97 MBH net AHRI water rating at 95% AFUE on the K2 condensing platform.
The U.S. Boiler Company K2WT-120B lists 120 MBH, against 100 MBH on the U.S. Boiler Company K2WT-100B, per the cited documentation.
Both list the same AFUE of 95%.
It ships at 105 lb against 102 lb for the U.S. Boiler Company K2WT-100B, 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.