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
U.S. Boiler Company K2WT-080B and U.S. Boiler Company K2WT-100B are two condensing boilers from the U.S. Boiler Company K2 line. Published ratings: U.S. Boiler Company K2WT-080B at 8–80 MBH input, 74 MBH heating capacity and 95% AFUE; U.S. Boiler Company K2WT-100B at 10–100 MBH input, 94 MBH heating capacity and 95% AFUE. U.S. Boiler Company K2WT-100B lists 20 MBH more input than U.S. Boiler Company K2WT-080B (100 MBH against 80 MBH). Both list the same published AFUE of 95%. U.S. Boiler Company K2WT-100B lists 2 lb more shipping weight than U.S. Boiler Company K2WT-080B (102 lb against 100 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-080B | U.S. Boiler Company K2WT-100B |
|---|---|---|
| Input, minimum | 8 MBH | 10 MBH |
| Input, maximum | 80 MBH | 100 MBH |
| DOE heating capacity | 74 MBH | 94 MBH |
| Net AHRI water rating | 64 MBH | 82 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 | 100 lb | 102 lb |
| Dimensions (A × B × C) | 16-3/16" × 3" × 7-3/8" (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" | 2" or 3" |
Published ratings: the U.S. Boiler Company K2WT-080B is rated 8–80 MBH input, 74 MBH heating capacity and 95% AFUE; the U.S. Boiler Company K2WT-100B is rated 10–100 MBH input, 94 MBH heating capacity and 95% AFUE. U.S. Boiler Company K2WT-100B lists 20 MBH more input than U.S. Boiler Company K2WT-080B (100 MBH against 80 MBH). Both list the same published AFUE of 95%.
U.S. Boiler Company K2WT-100B lists 2 lb more shipping weight than U.S. Boiler Company K2WT-080B (102 lb against 100 lb). The dimensions differs: the U.S. Boiler Company K2WT-080B lists 16-3/16" × 3" × 7-3/8" (A × B × C), while the U.S. Boiler Company K2WT-100B lists 16-3/16" × 3" × 7-7/16" (A × B × C).
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), venting (Direct vent, sealed combustion; universal connection for CPVC/PVC, polypropylene and stainless steel) and water connections (1" NPT supply and 1" NPT return), per the cited sources.
U.S. Boiler Company
The U.S. Boiler Company K2WT-080B is the smallest K2 watertube size with the lowest 8 MBH minimum fire: 8–80 MBH input with 74 MBH DOE heating capacity and a 64 MBH net AHRI water rating at 95% AFUE on the K2 condensing platform.
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.
The U.S. Boiler Company K2WT-100B lists 100 MBH, against 80 MBH on the U.S. Boiler Company K2WT-080B, per the cited documentation.
Both list the same AFUE of 95%.
It ships at 102 lb against 100 lb for the U.S. Boiler Company K2WT-080B, 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.